Adding new Date/Time operations (-, date_add, date_diff, date_part) (#7221)

- Adds `Column.date_diff` for computing date/time difference as integer multiply of some unit.
- Adds `Column.date_add` for shifting date/time by a unit.
- Adds `Column.date_part` for extracting various parts of the date/time value as integer.
- Adds widgets for the 3 methods above whose content depends on the column value type.
- Adds shorthands: `Column.hour`, `Column.minute` and `Column.second` to extract these date parts.
- Extends `Time_Period` with support for milli-, micro- and nano- seconds; and adapts functions taking `Time_Period` to support these wherever possible.

CHANGELOG.md

@@ -517,6 +517,9 @@
   `Column`, and in-memory `Table` to take a `Regex` in addition to a `Text`.]
   [7223]
 - [Added `cross_join` support to database tables.][7234]
+- [Improving date/time support in Table - added `date_diff`, `date_add`,
+  `date_part` and some shorthands. Extended `Time_Period` with milli-, micro-
+  and nanosecond periods.][7221]
 
 [debug-shortcuts]:
   https://github.com/enso-org/enso/blob/develop/app/gui/docs/product/shortcuts.md#debug
@@ -745,6 +748,7 @@
 [7174]: https://github.com/enso-org/enso/pull/7174
 [7223]: https://github.com/enso-org/enso/pull/7223
 [7234]: https://github.com/enso-org/enso/pull/7234
+[7221]: https://github.com/enso-org/enso/pull/7221
 
 #### Enso Compiler
 

distribution/lib/Standard/Base/0.0.0-dev/src/Data/Time/Date_Period.enso

@@ -2,27 +2,53 @@ import project.Data.Time.Date.Date
 import project.Data.Time.Date_Time.Date_Time
 import project.Data.Time.Day_Of_Week.Day_Of_Week
 import project.Data.Time.Period.Period
+import project.Error.Error
+import project.Errors.Illegal_State.Illegal_State
 from project.Data.Boolean import Boolean, False, True
 
+polyglot java import java.time.temporal.ChronoUnit
 polyglot java import java.time.temporal.TemporalAdjuster
 polyglot java import java.time.temporal.TemporalAdjusters
-polyglot java import org.enso.base.time.Date_Period_Utils
+polyglot java import java.time.temporal.TemporalUnit
 polyglot java import org.enso.base.Time_Utils
+polyglot java import org.enso.base.time.Date_Period_Utils
+polyglot java import org.enso.base.time.CustomTemporalUnits
 
 ## Represents a unit of time longer on the scale of days (longer than a day).
 type Date_Period
+    ## Represents a date period of a calendar year.
+
+       Its length in days will depend on context (accounting for leap years).
     Year
 
+    ## Represents a date period of a quarter - 3 calendar months.
     Quarter
 
+    ## Represents a date period of a month.
+
+       Its length in days will depend on context of what month it is used.
     Month
 
     ## Represents a 7-day week starting at a given day.
 
        By default, the first day of the week is Monday, but this can be adjusted
        to any other day.
+
+       The starting day will be ignored for methods that just compute the time
+       differences. It only matters for methods that need to find a beginning or
+       end of a specific period (like `start_of` or `end_of`).
+
+       The `date_part` method will return the ISO 8601 week of year number,
+       regardless of the starting day.
     Week (first_day:Day_Of_Week = Day_Of_Week.Monday)
 
+    ## Represents a time period of a single calendar day.
+
+       ? Daylight Saving Time
+
+         Note that due to DST changes, some days may be slightly longer or
+         shorter. This date period will reflect that and still count such days
+         as one day. For a measure of exactly 24 hours, use `Time_Period.Day`.
     Day
 
     ## PRIVATE
@@ -55,3 +81,12 @@ type Date_Period
         Date_Period.Month -> Period.new months=1
         Date_Period.Week _ -> Period.new days=7
         Date_Period.Day -> Period.new days=1
+
+    ## PRIVATE
+    to_java_unit : TemporalUnit
+    to_java_unit self = case self of
+        Date_Period.Year -> ChronoUnit.YEARS
+        Date_Period.Quarter -> CustomTemporalUnits.QUARTERS
+        Date_Period.Month -> ChronoUnit.MONTHS
+        Date_Period.Week _ -> ChronoUnit.WEEKS
+        Date_Period.Day -> ChronoUnit.DAYS

distribution/lib/Standard/Base/0.0.0-dev/src/Data/Time/Time_Period.enso

@@ -6,39 +6,76 @@ from project.Data.Boolean import Boolean, False, True
 polyglot java import java.time.temporal.ChronoUnit
 polyglot java import java.time.temporal.TemporalUnit
 polyglot java import org.enso.base.Time_Utils
+polyglot java import org.enso.base.time.CustomTemporalUnits
 
 ## Represents a unit of time of a day or shorter.
 type Time_Period
+    ## Represents a time period of a single day, measured as 24 hours.
+
+       ? Daylight Saving Time
+
+         Note that due to DST changes, some days may be slightly longer or
+         shorter. This is not reflected in the duration of this time period. For
+         a calendar-oriented day period, use `Date_Period.Day` instead.
     Day
 
+    ## Represents a time period of an hour.
     Hour
 
+    ## Represents a time period of a minute.
     Minute
 
+    ## Represents a time period of a second.
     Second
 
+    ## Represents a time period of a millisecond.
+    Millisecond
+
+    ## Represents a time period of a microsecond.
+    Microsecond
+
+    ## Represents a time period of a nanosecond.
+    Nanosecond
+
     ## PRIVATE
+       We treat the `Time_Period.Day` as a period of 24 hours, not a calendar day.
     to_java_unit : TemporalUnit
     to_java_unit self = case self of
-        Time_Period.Day -> ChronoUnit.DAYS
+        Time_Period.Day -> CustomTemporalUnits.DAY_AS_24_HOURS
         Time_Period.Hour -> ChronoUnit.HOURS
         Time_Period.Minute -> ChronoUnit.MINUTES
         Time_Period.Second -> ChronoUnit.SECONDS
+        Time_Period.Millisecond -> ChronoUnit.MILLIS
+        Time_Period.Microsecond -> ChronoUnit.MICROS
+        Time_Period.Nanosecond -> ChronoUnit.NANOS
+
+    ## PRIVATE
+       A special case for `adjust_start` and `adjust_end` methods.
+       In this particular case, it seems better to treat `Time_Period.Day` as a
+       calendar day. Otherwise, the behaviour of `start_of` and `end_of` methods
+       near DST would become unintuitive.
+    to_java_unit_for_adjust : TemporalUnit
+    to_java_unit_for_adjust self = case self of
+        Time_Period.Day -> ChronoUnit.DAYS
+        _ -> self.to_java_unit
 
     ## PRIVATE
     adjust_start : (Time_Of_Day | Date_Time) -> (Time_Of_Day | Date_Time)
     adjust_start self date =
-        (Time_Utils.utils_for date).start_of_time_period date self.to_java_unit
+        (Time_Utils.utils_for date).start_of_time_period date self.to_java_unit_for_adjust
 
     ## PRIVATE
     adjust_end : (Time_Of_Day | Date_Time) -> (Time_Of_Day | Date_Time)
     adjust_end self date =
-        (Time_Utils.utils_for date).end_of_time_period date self.to_java_unit
+        (Time_Utils.utils_for date).end_of_time_period date self.to_java_unit_for_adjust
 
     ## PRIVATE
     to_duration : Duration
     to_duration self = case self of
-        Time_Period.Day -> Duration.new 24
-        Time_Period.Hour -> Duration.new 1
-        Time_Period.Minute -> Duration.new 0 1
-        Time_Period.Second -> Duration.new 0 0 1
+        Time_Period.Day -> Duration.new hours=24
+        Time_Period.Hour -> Duration.new hours=1
+        Time_Period.Minute -> Duration.new minutes=1
+        Time_Period.Second -> Duration.new seconds=1
+        Time_Period.Millisecond -> Duration.new milliseconds=1
+        Time_Period.Microsecond -> Duration.new nanoseconds=1000
+        Time_Period.Nanosecond -> Duration.new nanoseconds=1

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Column.enso

@@ -7,6 +7,7 @@ import Standard.Base.Internal.Rounding_Helpers
 import Standard.Table.Data.Column.Column as Materialized_Column
 import Standard.Table.Data.Type.Enso_Types
 import Standard.Table.Data.Type.Value_Type_Helpers
+import Standard.Table.Internal.Date_Time_Helpers
 import Standard.Table.Internal.Java_Problems
 import Standard.Table.Internal.Problem_Builder.Problem_Builder
 import Standard.Table.Internal.Widget_Helpers
@@ -99,7 +100,7 @@ type Column
     ## Returns a vector containing all the elements in this column.
     to_vector : Vector Any
     to_vector self =
-        self.to_table.read . at self.name . to_vector
+        self.to_table.read . at 0 . to_vector
 
     ## Returns the `Value_Type` associated with that column.
 
@@ -133,8 +134,9 @@ type Column
        - operands: A vector of additional operation arguments (the column itself
          is always passed as the first argument).
        - new_name: The name of the resulting column.
-    make_op : Text -> Vector Text -> (Text | Nothing) -> Column
-    make_op self op_kind operands new_name =
+       - metadata: Optional metadata for the `SQL_Expression.Operation`.
+    make_op : Text -> Vector Text -> (Text | Nothing) -> (Any | Nothing) -> Column
+    make_op self op_kind operands new_name metadata=Nothing =
         checked_support = if self.connection.dialect.is_supported op_kind then True else
             Error.throw (Unsupported_Database_Operation.Error "The operation "+op_kind+" is not supported by this backend.")
         checked_support.if_not_error <|
@@ -149,7 +151,7 @@ type Column
                     SQL_Expression.Constant constant
 
             expressions = operands.map prepare_operand
-            new_expr = SQL_Expression.Operation op_kind ([self.expression] + expressions)
+            new_expr = SQL_Expression.Operation op_kind ([self.expression] + expressions) metadata
 
             infer_from_database_callback expression =
                 SQL_Type_Reference.new self.connection self.context expression
@@ -356,7 +358,7 @@ type Column
                 self.make_op "BETWEEN" [lower, upper] new_name
 
     ## ALIAS Add, Plus, Concatenate
-       Element-wise addition.
+       Element-wise addition. Works on numeric types or text.
 
        Arguments:
        - other: The other column to add to this column.
@@ -366,13 +368,16 @@ type Column
        between corresponding elements of `self` and `other`.
     + : Column | Any -> Column
     + self other =
-        op = Value_Type_Helpers.resolve_addition_kind self other
+        op = case Value_Type_Helpers.resolve_addition_kind self other of
+            Value_Type_Helpers.Addition_Kind.Numeric_Add -> "ADD_NUMBER"
+            Value_Type_Helpers.Addition_Kind.Text_Concat -> "ADD_TEXT"
         op.if_not_error <|
             new_name = self.naming_helpers.binary_operation_name "+" self other
             self.make_binary_op op other new_name
 
-    ## ALIAS Subtract, Minus
-       Element-wise subtraction.
+    ## ALIAS Subtract, Minus, Time Difference
+       Element-wise subtraction. Allows to subtract numeric types or compute a
+       difference between two date/time values.
 
        Arguments:
        - other: The other column to subtract from this column.
@@ -382,8 +387,11 @@ type Column
        pairwise between corresponding elements of `self` and `other`.
     - : Column | Any -> Column
     - self other =
-        Value_Type_Helpers.check_binary_numeric_op self other <|
-            self.make_binary_op "-" other
+        case Value_Type_Helpers.resolve_subtraction_kind self other of
+            Value_Type_Helpers.Subtraction_Kind.Numeric_Subtract ->
+                self.make_binary_op "-" other
+            Value_Type_Helpers.Subtraction_Kind.Date_Time_Difference ->
+                Error.throw (Unsupported_Database_Operation.Error "Subtracting date/time values is not supported in this database.")
 
     ## ALIAS Multiply, Times, Product
        Element-wise multiplication.
@@ -1144,7 +1152,7 @@ type Column
        Returns a column of `Integer` type.
     year : Column ! Invalid_Value_Type
     year self = Value_Type.expect_has_date self <|
-        self.make_unary_op "year"
+        simple_unary_op self "year"
 
     ## Gets the month as a number (1-12) from the date stored in the column.
 
@@ -1152,7 +1160,7 @@ type Column
        Returns a column of `Integer` type.
     month : Column ! Invalid_Value_Type
     month self = Value_Type.expect_has_date self <|
-        self.make_unary_op "month"
+        simple_unary_op self "month"
 
     ## Gets the day of the month as a number (1-31) from the date stored in the
        column.
@@ -1161,7 +1169,99 @@ type Column
        Returns a column of `Integer` type.
     day : Column ! Invalid_Value_Type
     day self = Value_Type.expect_has_date self <|
-        self.make_unary_op "day"
+        simple_unary_op self "day"
+
+    ## Gets the hour as a number (0-23) from the time stored in the column.
+
+       Applies only to columns that hold the `Time_Of_Day` or `Date_Time` types.
+       Returns a column of `Integer` type.
+    hour : Column ! Invalid_Value_Type
+    hour self = Value_Type.expect_has_time self <|
+        simple_unary_op self "hour"
+
+    ## Gets the minute as a number (0-59) from the time stored in the column.
+
+       Applies only to columns that hold the `Time_Of_Day` or `Date_Time` types.
+       Returns a column of `Integer` type.
+    minute : Column ! Invalid_Value_Type
+    minute self = Value_Type.expect_has_time self <|
+        simple_unary_op self "minute"
+
+    ## Gets the second as an integer (0-60) from the time stored in the column.
+
+       Applies only to columns that hold the `Time_Of_Day` or `Date_Time` types.
+       Returns a column of `Integer` type.
+    second : Column ! Invalid_Value_Type
+    second self = Value_Type.expect_has_time self <|
+        simple_unary_op self "second"
+
+    ## Gets the date part of the date/time value.
+
+       Returns a column of `Integer` type.
+    @period Date_Time_Helpers.make_period_selector_for_column
+    date_part : Date_Period | Time_Period -> Column ! Invalid_Value_Type
+    date_part self period =
+        Date_Time_Helpers.make_date_part_function self period simple_unary_op self.naming_helpers
+
+    ## Computes a time difference between the two dates.
+
+       It returns a column of integers expressing how many periods fit between
+       the two dates/times.
+
+       The difference will be positive if `end` is greater than `self`.
+
+       Arguments:
+       - end: A date/time column or a date/time value to compute the difference
+         from. It should have the same type as the current column, i.e. a
+         `Date_Time` column cannot be compared to a `Date` - to do so you first
+         need to `cast`.
+       - period: The period to compute the difference in. For `Date` columns it
+         should be a `Date_Period` and for `Time` columns it should be a
+         `Time_Period`. For `Date_Time` columns it can be either.
+
+       ? Time Zone handling
+
+         Some backends may not preserve the timezone data in a `Date_Time`
+         (preserving the represented time instant). This may lead to slight
+         differences in time calculations between backends, especially around
+         unusual events like DST.
+    @period Date_Time_Helpers.make_period_selector_for_column
+    date_diff : (Column | Date | Date_Time | Time_Of_Day) -> Date_Period | Time_Period -> Column
+    date_diff self end (period : Date_Period | Time_Period) =
+        Value_Type.expect_type self .is_date_or_time "date/time" <|
+            my_type = self.inferred_precise_value_type
+            Value_Type.expect_type end (== my_type) my_type.to_display_text <|
+                Date_Time_Helpers.check_period_aligned_with_value_type my_type period <|
+                    new_name = self.naming_helpers.function_name "date_diff" [self, end, period.to_display_text]
+                    metadata = self.connection.dialect.prepare_metadata_for_period period my_type
+                    self.make_op "date_diff" [end] new_name metadata
+
+    ## Shifts the date/time by a specified period, returning a new date/time
+       column of the same type.
+
+       Arguments:
+       - amount: An integer or integer column specifying by how many periods to
+         shift each date.
+       - period: The period by which to shift. For `Date` columns it should be a
+         `Date_Period` and for `Time` columns it should be a `Time_Period`. For
+         `Date_Time` columns it can be either.
+
+       ? Time Zone handling
+
+         Some backends may not preserve the timezone data in a `Date_Time`
+         (preserving the represented time instant). This may lead to slight
+         differences in time calculations between backends, especially around
+         unusual events like DST.
+    @period Date_Time_Helpers.make_period_selector_for_column
+    date_add : (Column | Integer) -> Date_Period | Time_Period -> Column
+    date_add self amount (period : Date_Period | Time_Period) =
+        Value_Type.expect_type self .is_date_or_time "date/time" <|
+            my_type = self.inferred_precise_value_type
+            Value_Type.expect_integer amount <|
+                Date_Time_Helpers.check_period_aligned_with_value_type my_type period <|
+                    new_name = self.naming_helpers.function_name "date_add" [self, amount, period.to_display_text]
+                    metadata = self.connection.dialect.prepare_metadata_for_period period my_type
+                    self.make_op "date_add" [amount] new_name metadata
 
     ## Checks for each element of the column if it is contained within the
        provided vector or column.
@@ -1471,3 +1571,8 @@ adapt_unified_column column expected_type =
         SQL_Type_Reference.new column.connection column.context expression
     adapted = dialect.adapt_unified_column column.as_internal expected_type infer_return_type
     Column.Value name=column.name connection=column.connection sql_type_reference=adapted.sql_type_reference expression=adapted.expression context=column.context
+
+## PRIVATE
+   A shorthand to be able to share the implementations between in-memory and
+   database.
+simple_unary_op column op_kind = column.make_unary_op op_kind

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Dialect.enso

@@ -223,6 +223,14 @@ type Dialect
         _ = [connection, table_name]
         Unimplemented.throw "This is an interface only."
 
+    ## PRIVATE
+       Prepares metadata for an operation taking a date/time period and checks
+       if the given period is supported.
+    prepare_metadata_for_period : Date_Period | Time_Period -> Value_Type -> Any
+    prepare_metadata_for_period self period operation_input_type =
+        _ = [period, operation_input_type]
+        Unimplemented.throw "This is an interface only."
+
 ## PRIVATE
 
    The dialect of SQLite databases.

distribution/lib/Standard/Database/0.0.0-dev/src/Data/Table.enso

@@ -45,6 +45,7 @@ import project.Internal.Helpers
 import project.Internal.IR.Context.Context
 import project.Internal.IR.From_Spec.From_Spec
 import project.Internal.IR.Internal_Column.Internal_Column
+import project.Internal.IR.Operation_Metadata
 import project.Internal.IR.Order_Descriptor.Order_Descriptor
 import project.Internal.IR.Query.Query
 import project.Internal.IR.SQL_Expression.SQL_Expression
@@ -580,11 +581,11 @@ type Table
                     descriptors -> descriptors
             grouping_expressions = grouping_columns.map .expression
 
-            separator = SQL_Expression.Literal Base_Generator.row_number_parameter_separator
             # The SQL row_number() counts from 1, so we adjust the offset.
             offset = from - step
-            params = [SQL_Expression.Constant offset, SQL_Expression.Constant step] + order_descriptors + [separator] + grouping_expressions
-            new_expr = SQL_Expression.Operation "ROW_NUMBER" params
+            params = [SQL_Expression.Constant offset, SQL_Expression.Constant step] + order_descriptors + grouping_expressions
+            metadata = Operation_Metadata.Row_Number_Metadata.Value grouping_expressions.length
+            new_expr = SQL_Expression.Operation "ROW_NUMBER" params metadata
 
             type_mapping = self.connection.dialect.get_type_mapping
             infer_from_database_callback expression =

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/Aggregate_Helper.enso

@@ -55,7 +55,7 @@ make_aggregate_column table aggregate new_name dialect infer_return_type problem
         Count_Empty c _ -> simple_aggregate "COUNT_EMPTY" [c]
         Percentile p c _ ->
             op_kind = "PERCENTILE"
-            expression = SQL_Expression.Operation op_kind [SQL_Expression.Constant p, c.expression]
+            expression = SQL_Expression.Operation op_kind [SQL_Expression.Literal p.to_text, c.expression]
             sql_type_ref = infer_return_type op_kind [c] expression
             Internal_Column.Value new_name sql_type_ref expression
         Mode c _ ->

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/Base_Generator.enso

@@ -11,6 +11,7 @@ import project.Internal.IR.Query.Query
 import project.Internal.IR.SQL_Expression.SQL_Expression
 import project.Internal.IR.SQL_Join_Kind.SQL_Join_Kind
 from project.Errors import Unsupported_Database_Operation
+from project.Internal.IR.Operation_Metadata import Row_Number_Metadata
 
 type Internal_Dialect
 
@@ -21,8 +22,9 @@ type Internal_Dialect
        Arguments:
        - operation_map: The mapping which maps operation names to their
          implementations; each implementation is a function which takes SQL
-         builders for the arguments and should return a builder yielding the
-         whole operation.
+         builders for the arguments, and optionally an additional metadata
+         argument, and should return a builder yielding code for the whole
+         operation.
        - wrap_identifier: A function that converts an arbitrary supported
          identifier name in such a way that it can be used in the query; that
          usually consists of wrapping the name in quotes and escaping any quotes
@@ -267,37 +269,18 @@ make_is_in_column arguments = case arguments.length of
 
 ## PRIVATE
 make_row_number : Vector Builder -> Builder
-make_row_number arguments = if arguments.length < 4 then Error.throw (Illegal_State.Error "Wrong amount of parameters in ROW_NUMBER IR. This is a bug in the Database library.") else
+make_row_number arguments (metadata : Row_Number_Metadata) = if arguments.length < 3 then Error.throw (Illegal_State.Error "Wrong amount of parameters in ROW_NUMBER IR. This is a bug in the Database library.") else
     offset = arguments.at 0
     step = arguments.at 1
 
-    separator_ix = arguments.index_of code->
-        code.build.prepare.first == row_number_parameter_separator
-    ordering = arguments.take (Range.new 2 separator_ix)
-    grouping = arguments.drop (separator_ix+1)
+    ordering_and_grouping = arguments.drop 2
+    ordering = ordering_and_grouping.drop (Last metadata.groupings_count)
+    grouping = ordering_and_grouping.take (Last metadata.groupings_count)
 
     group_part = if grouping.length == 0 then "" else
         Builder.code "PARTITION BY " ++ Builder.join ", " grouping
     Builder.code "(row_number() OVER (" ++ group_part ++ " ORDER BY " ++ Builder.join ", " ordering ++ ") * " ++ step.paren ++ " + " ++ offset.paren ++ ")"
 
-## PRIVATE
-   This is a terrible hack, but I could not figure a decent way to have an
-   operation take a variable number of arguments of multiple kinds (here both
-   groups and orders are varying).
-
-   Currently, the IR just allows to put a list of parameters for the operation
-   and they are all converted into SQL code before being passed to the
-   particular operation builder. So at this stage there is no way to distinguish
-   the arguments.
-
-   So to distinguish different groups of arguments, we use this 'fake' parameter
-   to act as a separator. This parameter is not supposed to end up in the
-   generated SQL code.
-
-   This is yet another argument for the IR redesign.
-row_number_parameter_separator =
-    "--<!PARAMETER_SEPARATOR!>--"
-
 ## PRIVATE
 
    Builds code for an expression.
@@ -311,10 +294,14 @@ generate_expression dialect expr = case expr of
         dialect.wrap_identifier origin ++ '.' ++ dialect.wrap_identifier name
     SQL_Expression.Constant value -> Builder.interpolation value
     SQL_Expression.Literal value -> Builder.code value
-    SQL_Expression.Operation kind arguments ->
+    SQL_Expression.Operation kind arguments metadata ->
         op = dialect.operation_map.get kind (Error.throw <| Unsupported_Database_Operation.Error kind)
         parsed_args = arguments.map (generate_expression dialect)
-        op parsed_args
+        result = op parsed_args
+        # If the function expects more arguments, we pass the metadata as the last argument.
+        case result of
+            _ : Function -> result metadata
+            _ -> result
     query : Query -> generate_query dialect query
     descriptor : Order_Descriptor -> generate_order dialect descriptor
 

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/IR/Operation_Metadata.enso

@@ -0,0 +1,13 @@
+from Standard.Base import all
+
+import Standard.Table.Data.Type.Value_Type.Value_Type
+
+## PRIVATE
+type Row_Number_Metadata
+    ## PRIVATE
+    Value groupings_count:Integer
+
+## PRIVATE
+type Date_Period_Metadata
+    ## PRIVATE
+    Value (period : Date_Period | Time_Period) (input_value_type : Value_Type)

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/IR/SQL_Expression.enso

@@ -47,4 +47,8 @@ type SQL_Expression
          dialect.
        - expressions: a list of expressions which are arguments to the operation
          different operations support different amounts of arguments.
-    Operation (kind : Text) (expressions : Vector SQL_Expression)
+       - metadata: additional metadata tied to the operation. This will be
+         `Nothing` for most operations, but some operations that need to be
+         parametrized by additional settings can use this field to pass that
+         information to the code generator.
+    Operation (kind : Text) (expressions : Vector SQL_Expression) (metadata : Any | Nothing = Nothing)

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/Postgres/Postgres_Dialect.enso

@@ -37,6 +37,7 @@ import project.Internal.SQL_Type_Mapping.SQL_Type_Mapping
 import project.Internal.SQL_Type_Reference.SQL_Type_Reference
 import project.Internal.Statement_Setter.Statement_Setter
 from project.Errors import SQL_Error, Unsupported_Database_Operation
+from project.Internal.IR.Operation_Metadata import Date_Period_Metadata
 
 ## PRIVATE
 
@@ -227,6 +228,17 @@ type Postgres_Dialect
     fetch_primary_key self connection table_name =
         Dialect.default_fetch_primary_key connection table_name
 
+    ## PRIVATE
+       Prepares metadata for an operation taking a date/time period and checks
+       if the given period is supported.
+    prepare_metadata_for_period : Date_Period | Time_Period -> Value_Type -> Any
+    prepare_metadata_for_period self period operation_input_type =
+        case period of
+            Time_Period.Nanosecond ->
+                Error.throw (Unsupported_Database_Operation.Error "Postgres backend does not support nanosecond precision in date/time operations.")
+            _ ->
+                Date_Period_Metadata.Value period operation_input_type
+
 ## PRIVATE
 make_internal_generator_dialect =
     cases = [["LOWER", Base_Generator.make_function "LOWER"], ["UPPER", Base_Generator.make_function "UPPER"]]
@@ -238,7 +250,7 @@ make_internal_generator_dialect =
     stddev_pop = ["STDDEV_POP", Base_Generator.make_function "stddev_pop"]
     stddev_samp = ["STDDEV_SAMP", Base_Generator.make_function "stddev_samp"]
     stats = [agg_median, agg_mode, agg_percentile, stddev_pop, stddev_samp]
-    date_ops = [make_extract_as_int "year" "YEAR", make_extract_as_int "month" "MONTH", make_extract_as_int "day" "DAY"]
+    date_ops = [make_extract_as_int "year", make_extract_as_int "quarter", make_extract_as_int "month", make_extract_as_int "week", make_extract_as_int "day", make_extract_as_int "hour", make_extract_as_int "minute", make_extract_fractional_as_int "second", make_extract_fractional_as_int "millisecond" modulus=1000, make_extract_fractional_as_int "microsecond" modulus=1000, ["date_add", make_date_add], ["date_diff", make_date_diff]]
     special_overrides = [is_null, is_empty]
     my_mappings = text + counts + stats + first_last_aggregators + arith_extensions + bool + date_ops + special_overrides
     Base_Generator.base_dialect . extend_with my_mappings
@@ -481,10 +493,130 @@ decimal_mod = Base_Generator.lift_binary_op "DECIMAL_MOD" x-> y->
     x ++ " - FLOOR(CAST(" ++ x ++ " AS decimal) / CAST(" ++ y ++ " AS decimal)) * " ++ y
 
 ## PRIVATE
-make_extract_as_int enso_name sql_name =
+make_extract_as_int enso_name sql_name=enso_name =
     Base_Generator.lift_unary_op enso_name arg->
-        extract = Builder.code "EXTRACT(" ++ sql_name ++ " FROM " ++ arg ++ ")"
-        Builder.code "CAST(" ++ extract ++ " AS integer)"
+        as_int32 <| Builder.code "EXTRACT(" ++ sql_name ++ " FROM " ++ arg ++ ")"
+
+## PRIVATE
+make_extract_fractional_as_int enso_name sql_name=enso_name modulus=Nothing =
+    Base_Generator.lift_unary_op enso_name arg->
+        result = as_int32 <| Builder.code "TRUNC(EXTRACT(" ++ sql_name ++ " FROM " ++ arg ++ "))"
+        case modulus of
+            Nothing -> result
+            _ : Integer ->
+                (result ++ (" % "+modulus.to_text)).paren
+
+## PRIVATE
+make_date_add arguments (metadata : Date_Period_Metadata) =
+    if arguments.length != 2 then Error.throw (Illegal_State.Error "date_add expects exactly 2 sub expressions. This is a bug in Database library.") else
+        expr = arguments.at 0
+        amount = arguments.at 1
+        interval_arg = case metadata.period of
+            Date_Period.Year ->
+                "years=>1"
+            Date_Period.Quarter ->
+                "months=>3"
+            Date_Period.Month ->
+                "months=>1"
+            Date_Period.Week _ ->
+                "weeks=>1"
+            Date_Period.Day ->
+                "days=>1"
+            Time_Period.Day ->
+                "hours=>24"
+            Time_Period.Hour ->
+                "hours=>1"
+            Time_Period.Minute ->
+                "mins=>1"
+            Time_Period.Second ->
+                "secs=>1"
+            Time_Period.Millisecond ->
+                "secs=>0.001"
+            Time_Period.Microsecond ->
+                "secs=>0.000001"
+        interval_expression = Builder.code "make_interval(" ++ interval_arg ++ ")"
+        shifted = Builder.code "(" ++ expr ++ " + (" ++ amount ++ " * " ++ interval_expression ++ "))"
+        case metadata.input_value_type of
+            Value_Type.Date ->
+                Builder.code "(" ++ shifted ++ "::date)"
+            _ -> shifted
+
+## PRIVATE
+make_date_diff arguments (metadata : Date_Period_Metadata) =
+    if arguments.length != 2 then Error.throw (Illegal_State.Error "date_diff expects exactly 2 sub expressions. This is a bug in Database library.") else
+        start = arguments.at 0
+        end = arguments.at 1
+
+        truncate expr =
+            Builder.code "TRUNC(" ++ expr ++ ")"
+
+        # `age` computes a 'symbolic' difference expressed in years, months and days.
+        extract_years =
+            as_int32 <| Builder.code "EXTRACT(YEARS FROM age(" ++ end ++ ", " ++ start ++ "))"
+        # To get total months, we need to sum up with whole years.
+        extract_months =
+            months = as_int32 <|
+                Builder.code "EXTRACT(MONTHS FROM age(" ++ end ++ ", " ++ start ++ "))"
+            Builder.code "(" ++ extract_years ++ " * 12 + " ++ months ++ ")"
+        ## To get total days, we cannot use `age`, because we cannot convert an
+           amount of months to days (month lengths vary). Instead we rely on `-`
+           returning an interval based in 'raw' days.
+        extract_days =
+            as_int32 <| case metadata.input_value_type of
+                ## For pure 'date' datatype, the difference is a simple integer
+                   count of days.
+                Value_Type.Date -> (end ++ " - " ++ start).paren
+                # For others, it is an interval, so we need to extract.
+                _ -> Builder.code "EXTRACT(DAYS FROM (" ++ end ++ " - " ++ start ++ "))"
+        ## We round the amount of seconds towards zero, as we only count full
+           elapsed seconds in the interval.
+           Note that it is important the interval is computed using `-`. The
+           symbolic `age` has no clear mapping to the count of days, skewing the
+           result.
+        extract_seconds =
+            seconds_numeric = Builder.code "EXTRACT(EPOCH FROM (" ++ end ++ " - " ++ start ++ "))"
+            as_int64 (truncate seconds_numeric)
+        case metadata.period of
+            Date_Period.Year    -> extract_years
+            Date_Period.Month   -> extract_months
+            Date_Period.Quarter -> (extract_months ++ " / 3").paren
+            Date_Period.Week _  -> (extract_days ++ " / 7").paren
+            Date_Period.Day     -> extract_days
+            ## EXTRACT HOURS/MINUTES would yield only a date part, but we need
+               the total which is easiest achieved by EPOCH
+            Time_Period.Hour    -> (extract_seconds ++ " / 3600").paren
+            Time_Period.Minute  -> (extract_seconds ++ " / 60").paren
+            Time_Period.Second  -> extract_seconds
+            Time_Period.Day     -> case metadata.input_value_type of
+                Value_Type.Date -> extract_days
+                # Time_Period.Day is treated as 24 hours, so for types that support time we use the same algorithm like for hours, but divide by 24.
+                _ -> (extract_seconds ++ " / (3600 * 24)").paren
+            ## The EPOCH gives back just the integer amount of seconds, without
+               the fractional part. So we get the fractional part using
+               MILLISECONDS - but that does not give the _total_ just the
+               'seconds of minute' part, expressed in milliseconds. So we need
+               to merge both - but then seconds of minute appear twice, so we %
+               the milliseconds to get just the fractional part from it and sum
+               both.
+            Time_Period.Millisecond ->
+                millis = truncate <|
+                    Builder.code "EXTRACT(MILLISECONDS FROM (" ++ end ++ " - " ++ start ++ "))"
+                as_int64 <|
+                    ((extract_seconds ++ " * 1000").paren ++ " + " ++ (millis ++ " % 1000").paren).paren
+            Time_Period.Microsecond ->
+                micros = Builder.code "EXTRACT(MICROSECONDS FROM (" ++ end ++ " - " ++ start ++ "))"
+                as_int64 <|
+                    ((extract_seconds ++ " * 1000000").paren ++ " + " ++ (micros ++ " % 1000000").paren).paren
+
+## PRIVATE
+   Alters the expression casting the value to a 64-bit integer.
+as_int64 expr =
+    Builder.code "(" ++ expr ++ "::int8)"
+
+## PRIVATE
+   Alters the expression casting the value to a 32-bit integer (the default choice for integers in Postgres).
+as_int32 expr =
+    Builder.code "(" ++ expr ++ "::int4)"
 
 ## PRIVATE
 postgres_statement_setter = Statement_Setter.default

distribution/lib/Standard/Database/0.0.0-dev/src/Internal/SQLite/SQLite_Dialect.enso

@@ -257,6 +257,14 @@ type SQLite_Dialect
         v = info_table.filter "pk" (>0) . order_by "pk" . at "name" . to_vector
         if v.is_empty then Nothing else v
 
+    ## PRIVATE
+       Prepares metadata for an operation taking a date/time period and checks
+       if the given period is supported.
+    prepare_metadata_for_period : Date_Period | Time_Period -> Value_Type -> Any
+    prepare_metadata_for_period self period operation_input_type =
+        _ = [period, operation_input_type]
+        Error.throw (Unsupported_Database_Operation.Error "SQLite backend does not support date/time operations.")
+
 ## PRIVATE
 make_internal_generator_dialect =
     text = [starts_with, contains, ends_with, make_case_sensitive]+concat_ops+trim_ops

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Column.enso

@@ -13,6 +13,7 @@ import project.Data.Type.Storage
 import project.Data.Type.Value_Type_Helpers
 import project.Internal.Cast_Helpers
 import project.Internal.Column_Ops
+import project.Internal.Date_Time_Helpers
 import project.Internal.Java_Problems
 import project.Internal.Naming_Helpers.Naming_Helpers
 import project.Internal.Parse_Values_Helper
@@ -23,6 +24,7 @@ from project.Errors import Conversion_Failure, Floating_Point_Equality, Inexact_
 from project.Internal.Column_Format import all
 from project.Internal.Java_Exports import make_date_builder_adapter, make_double_builder, make_long_builder, make_string_builder
 
+polyglot java import org.enso.base.Time_Utils
 polyglot java import org.enso.table.data.column.operation.map.MapOperationProblemBuilder
 polyglot java import org.enso.table.data.column.storage.Storage as Java_Storage
 polyglot java import org.enso.table.data.table.Column as Java_Column
@@ -358,7 +360,7 @@ type Column
                 result.rename new_name
 
     ## ALIAS Add, Plus, Concatenate
-       Element-wise addition.
+       Element-wise addition. Works on numeric types or text.
 
        Arguments:
        - other: The value to add to `self`. If `other` is a column, the addition
@@ -387,7 +389,8 @@ type Column
             run_vectorized_binary_op self '+' fallback_fn=Nothing other
 
     ## ALIAS Subtract, Minus
-       Element-wise subtraction.
+       Element-wise subtraction. Allows to subtract numeric types or compute a
+       difference between two date/time values.
 
        Arguments:
        - other: The value to subtract from `self`. If `other` is a column, the
@@ -412,8 +415,22 @@ type Column
              example_minus = Examples.integer_column - 10
     - : Column | Any -> Column
     - self other =
-        Value_Type_Helpers.check_binary_numeric_op self other <|
-            run_vectorized_binary_op self '-' fallback_fn=Nothing other
+        case Value_Type_Helpers.resolve_subtraction_kind self other of
+            Value_Type_Helpers.Subtraction_Kind.Numeric_Subtract ->
+                run_vectorized_binary_op self '-' fallback_fn=Nothing other
+            Value_Type_Helpers.Subtraction_Kind.Date_Time_Difference ->
+                case self.inferred_precise_value_type of
+                    Value_Type.Date ->
+                        ## Special handling for `Period` since it is hard to
+                           vectorize as there is no polyglot handling of it - we
+                           _wrap_ a Java object and the Java wrapper will always
+                           be an Enso callback, at which point its better to do
+                           the whole operation in pure Enso.
+                        fn = x-> y-> Period.between y x
+                        new_name = Naming_Helpers.binary_operation_name "-" self other
+                        run_binary_op self other fn new_name
+                    _ ->
+                        run_vectorized_binary_op self '-' fallback_fn=Nothing other
 
     ## ALIAS Multiply, Times, Product
        Element-wise multiplication.
@@ -1239,6 +1256,108 @@ type Column
     day self = Value_Type.expect_has_date self <|
         simple_unary_op self "day"
 
+    ## Gets the hour as a number (0-23) from the time stored in the column.
+
+       Applies only to columns that hold the `Time_Of_Day` or `Date_Time` types.
+       Returns a column of `Integer` type.
+    hour : Column ! Invalid_Value_Type
+    hour self = Value_Type.expect_has_time self <|
+        simple_unary_op self "hour"
+
+    ## Gets the minute as a number (0-59) from the time stored in the column.
+
+       Applies only to columns that hold the `Time_Of_Day` or `Date_Time` types.
+       Returns a column of `Integer` type.
+    minute : Column ! Invalid_Value_Type
+    minute self = Value_Type.expect_has_time self <|
+        simple_unary_op self "minute"
+
+    ## Gets the second as an integer (0-60) from the time stored in the column.
+
+       Applies only to columns that hold the `Time_Of_Day` or `Date_Time` types.
+       Returns a column of `Integer` type.
+    second : Column ! Invalid_Value_Type
+    second self = Value_Type.expect_has_time self <|
+        simple_unary_op self "second"
+
+    ## Gets the date part of the date/time value.
+
+       Returns a column of `Integer` type.
+    @period Date_Time_Helpers.make_period_selector_for_column
+    date_part : Date_Period | Time_Period -> Column ! Invalid_Value_Type
+    date_part self period =
+        Date_Time_Helpers.make_date_part_function self period simple_unary_op Naming_Helpers
+
+    ## Computes a time difference between the two dates.
+
+       It returns a column of integers expressing how many periods fit between
+       the two dates/times.
+
+       The difference will be positive if `end` is greater than `self`.
+
+       Arguments:
+       - end: A date/time column or a date/time value to compute the difference
+         from. It should have the same type as the current column, i.e. a
+         `Date_Time` column cannot be compared to a `Date` - to do so you first
+         need to `cast`.
+       - period: The period to compute the difference in. For `Date` columns it
+         should be a `Date_Period` and for `Time` columns it should be a
+         `Time_Period`. For `Date_Time` columns it can be either.
+
+       ? Time Zone handling
+
+         Some backends may not preserve the timezone data in a `Date_Time`
+         (preserving the represented time instant). This may lead to slight
+         differences in time calculations between backends, especially around
+         unusual events like DST.
+    @period Date_Time_Helpers.make_period_selector_for_column
+    date_diff : (Column | Date | Date_Time | Time_Of_Day) -> Date_Period | Time_Period -> Column
+    date_diff self end (period : Date_Period | Time_Period) =
+        Value_Type.expect_type self .is_date_or_time "date/time" <|
+            my_type = self.inferred_precise_value_type
+            Value_Type.expect_type end (== my_type) my_type.to_display_text <|
+                Date_Time_Helpers.check_period_aligned_with_value_type my_type period <|
+                    new_name = Naming_Helpers.function_name "date_diff" [self, end, period.to_display_text]
+                    java_unit = period.to_java_unit
+                    fn = case my_type of
+                        Value_Type.Date_Time _ ->
+                            start-> end-> Time_Utils.unit_datetime_difference java_unit start end
+                        Value_Type.Date ->
+                            start-> end-> Time_Utils.unit_date_difference java_unit start end
+                        Value_Type.Time ->
+                            start-> end-> Time_Utils.unit_time_difference java_unit start end
+                    run_binary_op self end fn new_name
+
+
+    ## Shifts the date/time by a specified period, returning a new date/time
+       column of the same type.
+
+       Arguments:
+       - amount: An integer or integer column specifying by how many periods to
+         shift each date.
+       - period: The period by which to shift. For `Date` columns it should be a
+         `Date_Period` and for `Time` columns it should be a `Time_Period`. For
+         `Date_Time` columns it can be either.
+
+       ? Time Zone handling
+
+         Some backends may not preserve the timezone data in a `Date_Time`
+         (preserving the represented time instant). This may lead to slight
+         differences in time calculations between backends, especially around
+         unusual events like DST.
+    @period Date_Time_Helpers.make_period_selector_for_column
+    date_add : (Column | Integer) -> Date_Period | Time_Period -> Column
+    date_add self amount (period : Date_Period | Time_Period) =
+        Value_Type.expect_type self .is_date_or_time "date/time" <|
+            my_type = self.inferred_precise_value_type
+            Value_Type.expect_integer amount <|
+                Date_Time_Helpers.check_period_aligned_with_value_type my_type period <|
+                    new_name = Naming_Helpers.function_name "date_add" [self, amount, period.to_display_text]
+                    java_unit = period.to_java_unit
+                    fn date amount =
+                        java_unit.addTo date amount
+                    run_binary_op self amount fn new_name
+
     ## Checks for each element of the column if it is contained within the
        provided vector or column.
 
@@ -1971,6 +2090,15 @@ run_vectorized_binary_op column name fallback_fn operand expected_result_type=No
     Problem_Behavior.Report_Warning.attach_problems_after result <|
         Java_Problems.parse_aggregated_problems problem_builder.getProblems
 
+## PRIVATE
+   Runs a binary operation over the provided column and operand which may be
+   another column or a scalar value.
+run_binary_op column operand function new_name =
+    new_column = case operand of
+        _ : Column -> column.zip operand function
+        _ -> column.map (function _ operand)
+    new_column.rename new_name
+
 ## PRIVATE
 
    Executes a vectorized binary operation over the provided column.

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Type/Value_Type.enso

@@ -188,6 +188,23 @@ type Value_Type
         Value_Type.Date_Time _ -> True
         _ -> False
 
+    ## Checks if the `Value_Type` represents a type that holds a time of day.
+
+       It will return true for both `Time_Of_Day` and `Date_Time` types.
+    has_time : Boolean
+    has_time self = case self of
+        Value_Type.Time -> True
+        Value_Type.Date_Time _ -> True
+        _ -> False
+
+    ## Checks if the `Value_Type` represents a date/time type.
+    is_date_or_time : Boolean
+    is_date_or_time self = case self of
+        Value_Type.Date -> True
+        Value_Type.Date_Time _ -> True
+        Value_Type.Time -> True
+        _ -> False
+
     ## PRIVATE
        Specifies if values of the given type can be compared for ordering.
     has_ordering : Boolean
@@ -283,7 +300,7 @@ type Value_Type
        a text type and runs the following action or reports a type error.
     expect_text : Any -> Any -> Any ! Invalid_Value_Type
     expect_text argument ~action =
-        expect_type argument .is_text "Char" action
+        Value_Type.expect_type argument .is_text "Char" action
 
     ## PRIVATE
        ADVANCED
@@ -291,7 +308,7 @@ type Value_Type
        a text type and runs the following action or reports a type error.
     expect_boolean : Any -> Any -> Any ! Invalid_Value_Type
     expect_boolean argument ~action =
-        expect_type argument .is_boolean Value_Type.Boolean action
+        Value_Type.expect_type argument .is_boolean Value_Type.Boolean action
 
     ## PRIVATE
        ADVANCED
@@ -299,7 +316,7 @@ type Value_Type
        a numeric type and runs the following action or reports a type error.
     expect_numeric : Any -> Any -> Any ! Invalid_Value_Type
     expect_numeric argument ~action =
-        expect_type argument .is_numeric "a numeric" action
+        Value_Type.expect_type argument .is_numeric "a numeric" action
 
     ## PRIVATE
        ADVANCED
@@ -308,15 +325,42 @@ type Value_Type
        error.
     expect_floating_point : Any -> Any -> Any ! Invalid_Value_Type
     expect_floating_point argument ~action =
-        expect_type argument .is_floating_point "Float" action
+        Value_Type.expect_type argument .is_floating_point "Float" action
 
     ## PRIVATE
        ADVANCED
-       Checks if the provided argument (which may be a value or a Column) is has
+       Checks if the provided argument (which may be a value or a Column) is of
+       an integer type and runs the following action or reports a type error.
+    expect_integer : Any -> Any -> Any ! Invalid_Value_Type
+    expect_integer argument ~action =
+        Value_Type.expect_type argument .is_integer "Integer" action
+
+    ## PRIVATE
+       ADVANCED
+       Checks if the provided argument (which may be a value or a Column) has
        type `Date` or `Date_Time`.
     expect_has_date : Any -> Any -> Any ! Invalid_Value_Type
     expect_has_date argument ~action =
-        expect_type argument .has_date "Date or Date_Time" action
+        Value_Type.expect_type argument .has_date "Date or Date_Time" action
+
+    ## PRIVATE
+       ADVANCED
+       Checks if the provided argument (which may be a value or a Column) has
+       type `Time_Of_Day` or `Date_Time`.
+    expect_has_time : Any -> Any -> Any ! Invalid_Value_Type
+    expect_has_time argument ~action =
+        Value_Type.expect_type argument .has_time "Time_Of_Day or Date_Time" action
+
+    ## PRIVATE
+       A helper for generating the `Value_Type.expect_` checks.
+    expect_type : Any -> (Value_Type -> Boolean) -> Text|Value_Type -> Any -> Any ! Invalid_Value_Type
+    expect_type value predicate type_kind ~action = case value of
+        # Special handling for `Nothing`. Likely, can be removed with #6281.
+        Nothing -> action
+        _ ->
+            typ = Value_Type_Helpers.find_argument_type value
+            if predicate typ then action else
+                Value_Type_Helpers.raise_unexpected_type type_kind value
 
     ## PRIVATE
        Provides a text representation of the `Value_Type` meant for
@@ -373,14 +417,3 @@ type Value_Type
    - otherwise, `Text` is chosen as a fallback and the column is kept as-is
      without parsing.
 type Auto
-
-## PRIVATE
-   A helper for generating the `Value_Type.expect_` checks.
-expect_type : Any -> (Value_Type -> Boolean) -> Text|Value_Type -> Any -> Any ! Invalid_Value_Type
-expect_type value predicate type_kind ~action = case value of
-    # Special handling for `Nothing`. Likely, can be removed with #6281.
-    Nothing -> action
-    _ ->
-        typ = Value_Type_Helpers.find_argument_type value
-        if predicate typ then action else
-            Value_Type_Helpers.raise_unexpected_type type_kind value

distribution/lib/Standard/Table/0.0.0-dev/src/Data/Type/Value_Type_Helpers.enso

@@ -94,6 +94,14 @@ find_argument_type value = if Nothing == value then Nothing else
             col_type = value.value_type
             if col_type == Value_Type.Mixed then value.inferred_precise_value_type else col_type
 
+## PRIVATE
+type Addition_Kind
+    ## PRIVATE
+    Numeric_Add
+
+    ## PRIVATE
+    Text_Concat
+
 ## PRIVATE
    A helper which resolves if numeric addition or string concatenation should be
    used when the a `+` operator is used with the two provided types.
@@ -101,12 +109,36 @@ find_argument_type value = if Nothing == value then Nothing else
 resolve_addition_kind arg1 arg2 =
     type_1 = find_argument_type arg1
     type_2 = find_argument_type arg2
-    if type_1.is_numeric && (type_2.is_nothing || type_2.is_numeric) then 'ADD_NUMBER' else
-        if type_1.is_text && (type_2.is_nothing || type_2.is_text) then 'ADD_TEXT' else
+    if type_1.is_numeric && (type_2.is_nothing || type_2.is_numeric) then Addition_Kind.Numeric_Add else
+        if type_1.is_text && (type_2.is_nothing || type_2.is_text) then Addition_Kind.Text_Concat else
             Error.throw <| Illegal_Argument.Error <|
                 if type_2.is_nothing then "Cannot perform addition on a value of type " + type_1.to_display_text + ". Addition can only be performed if the column is of some numeric type or is text." else
                     "Cannot perform addition on a pair of values of types " + type_1.to_display_text + " and " + type_2.to_display_text + ". Addition can only be performed if both columns are of some numeric type or are both are text."
 
+## PRIVATE
+type Subtraction_Kind
+    ## PRIVATE
+    Numeric_Subtract
+
+    ## PRIVATE
+    Date_Time_Difference
+
+## PRIVATE
+   A helper which resolves if numeric subtraction or date-time difference should
+   be used when the a `-` operator is used with the two provided types.
+   It will return an error if the provided types are incompatible.
+resolve_subtraction_kind arg1 arg2 =
+    type_1 = find_argument_type arg1
+    type_2 = find_argument_type arg2
+
+    if type_1.is_numeric && (type_2.is_nothing || type_2.is_numeric) then Subtraction_Kind.Numeric_Subtract else
+        case type_1.is_date_or_time of
+            True ->
+                if type_2.is_nothing || (type_2 == type_1) then Subtraction_Kind.Date_Time_Difference else
+                    raise_unexpected_type type_1 arg2
+            False ->
+                raise_unexpected_type "numeric or date/time" arg1
+
 ## PRIVATE
    Checks that both provided arguments have numeric type and runs the action
    if they do.

distribution/lib/Standard/Table/0.0.0-dev/src/Internal/Date_Time_Helpers.enso

@@ -0,0 +1,66 @@
+from Standard.Base import all
+import Standard.Base.Errors.Illegal_Argument.Illegal_Argument
+import Standard.Base.Metadata.Display
+import Standard.Base.Metadata.Widget
+from Standard.Base.Metadata.Choice import Option
+from Standard.Base.Metadata.Widget import Single_Choice
+
+import project.Data.Column.Column
+import project.Data.Type.Value_Type.Value_Type
+
+## PRIVATE
+check_period_aligned_with_value_type value_type period ~action = case value_type of
+    Value_Type.Date ->
+        ## We don't 'officially' allow `Time_Period` for Date, but since
+           `Time_Period.Day` and `Date_Period.Day` in this context can be
+           interchangeable, we allow it as an exception.
+        if (period.is_a Date_Period) || (period == Time_Period.Day) then action else
+            Error.throw (Illegal_Argument.Error "`Time_Period` is not allowed for Date columns. Use `Date_Period`.")
+    Value_Type.Time ->
+        case period of
+            _ : Date_Period ->
+                Error.throw (Illegal_Argument.Error "`Date_Period` is not allowed for Time columns. Use `Time_Period`.")
+            Time_Period.Day ->
+                Error.throw (Illegal_Argument.Error "`Time_Period.Day` does not make sense for Time columns.")
+            _ -> action
+    Value_Type.Date_Time _ ->
+        ## Both kinds are allowed for `Date_Time` columns.
+        action
+
+## PRIVATE
+   Common logic for `Column.date_part`.
+make_date_part_function column period make_unary_op naming_helpers =
+    Value_Type.expect_type column .is_date_or_time "date/time" <|
+        my_type = column.inferred_precise_value_type
+        check_period_aligned_with_value_type my_type period <|
+            new_name = naming_helpers.function_name "date_part" [column, period]
+            result = case period of
+                Date_Period.Year -> make_unary_op column "year"
+                Date_Period.Quarter -> make_unary_op column "quarter"
+                Date_Period.Month -> make_unary_op column "month"
+                Date_Period.Week _ -> make_unary_op column "week"
+                Date_Period.Day -> make_unary_op column "day"
+                Time_Period.Day -> make_unary_op column "day"
+                Time_Period.Hour -> make_unary_op column "hour"
+                Time_Period.Minute -> make_unary_op column "minute"
+                Time_Period.Second -> make_unary_op column "second"
+                Time_Period.Millisecond -> make_unary_op column "millisecond"
+                Time_Period.Microsecond -> make_unary_op column "microsecond"
+                Time_Period.Nanosecond -> make_unary_op column "nanosecond"
+            result.rename new_name
+
+## PRIVATE
+make_period_selector_for_column : Column -> Widget
+make_period_selector_for_column column =
+    column_type = column.inferred_precise_value_type
+    date_periods = ["Year", "Quarter", "Month", "Week", "Day"].map name->
+        Option name "Date_Period."+name
+    time_periods = ["Hour", "Minute", "Second", "Millisecond", "Microsecond", "Nanosecond"].map name->
+        Option name "Time_Period."+name
+    values = case column_type of
+        Value_Type.Date -> date_periods
+        Value_Type.Date_Time _ -> date_periods + time_periods
+        Value_Type.Time -> time_periods
+        # Some fallback is needed for the type mismatch case. Throwing an error will not work as expected as just the widget code will fail. (TODO right?)
+        _ -> [Option ("Expected a date/time column but got "+column_type.to_display_text+".") "Date_Period.Day"]
+    Single_Choice display=Display.Always values=values

std-bits/base/src/main/java/org/enso/base/Time_Utils.java

@@ -17,6 +17,7 @@ import java.time.format.DateTimeFormatter;
 import java.time.format.DateTimeFormatterBuilder;
 import java.time.temporal.ChronoUnit;
 import java.time.temporal.TemporalField;
+import java.time.temporal.TemporalUnit;
 import java.time.temporal.WeekFields;
 import java.util.Locale;
 
@@ -266,4 +267,31 @@ public class Time_Utils {
   public static ZonedDateTime with_zone_same_instant(ZonedDateTime dateTime, ZoneId zone) {
     return dateTime.withZoneSameInstant(zone);
   }
+
+  /**
+   * This wrapper function is needed to ensure that EnsoDate gets converted to LocalDate correctly.
+   * <p>
+   * The {@code ChronoUnit::between} takes a value of type Temporal which does not trigger a polyglot conversion.
+   */
+  public static long unit_date_difference(TemporalUnit unit, LocalDate start, LocalDate end) {
+    return unit.between(start, end);
+  }
+
+  /**
+   * This wrapper function is needed to ensure that EnsoTimeOfDay gets converted to LocalTime correctly.
+   * <p>
+   * The {@code ChronoUnit::between} takes a value of type Temporal which does not trigger a polyglot conversion.
+   */
+  public static long unit_time_difference(TemporalUnit unit, LocalTime start, LocalTime end) {
+    return unit.between(start, end);
+  }
+
+  /**
+   * This wrapper function is needed to ensure that EnsoDateTime gets converted to ZonedDateTime correctly.
+   * <p>
+   * The {@code ChronoUnit::between} takes a value of type Temporal which does not trigger a polyglot conversion.
+   */
+  public static long unit_datetime_difference(TemporalUnit unit, ZonedDateTime start, ZonedDateTime end) {
+    return unit.between(start, end);
+  }
 }

std-bits/base/src/main/java/org/enso/base/time/CustomTemporalUnits.java

@@ -0,0 +1,97 @@
+package org.enso.base.time;
+
+import java.time.Duration;
+import java.time.temporal.ChronoUnit;
+import java.time.temporal.Temporal;
+import java.time.temporal.TemporalUnit;
+
+/**
+ * Some units that are not available in ChronoUnit but are used by Enso's Date_Period/Time_Period.
+ */
+public class CustomTemporalUnits {
+  /**
+   * A unit that represents a 24-hour period.
+   *
+   * <p>It will behave differently from DAYS if DST is involved in time-supporting Temporal values.
+   * However, if a pure-date-based Temporal value is provided (one that does not support time), it
+   * will act exactly as DAYS.
+   */
+  public static final TemporalUnit DAY_AS_24_HOURS = new DayAs24Hours();
+
+  public static final TemporalUnit QUARTERS = new Quarters();
+
+  private static class DayAs24Hours implements TemporalUnit {
+    private final Duration duration = Duration.ofHours(24);
+
+    @Override
+    public Duration getDuration() {
+      return duration;
+    }
+
+    @Override
+    public boolean isDurationEstimated() {
+      return false;
+    }
+
+    @Override
+    public boolean isDateBased() {
+      return true;
+    }
+
+    @Override
+    public boolean isTimeBased() {
+      return true;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public <R extends Temporal> R addTo(R temporal, long amount) {
+      if (temporal.isSupported(ChronoUnit.HOURS)) {
+        return (R) temporal.plus(amount * 24, ChronoUnit.HOURS);
+      } else {
+        return (R) temporal.plus(amount, ChronoUnit.DAYS);
+      }
+    }
+
+    @Override
+    public long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive) {
+      if (temporal1Inclusive.isSupported(ChronoUnit.HOURS)) {
+        return ChronoUnit.HOURS.between(temporal1Inclusive, temporal2Exclusive) / 24;
+      } else {
+        return ChronoUnit.DAYS.between(temporal1Inclusive, temporal2Exclusive);
+      }
+    }
+  }
+
+  private static class Quarters implements TemporalUnit {
+    @Override
+    public Duration getDuration() {
+      return ChronoUnit.MONTHS.getDuration().multipliedBy(3);
+    }
+
+    @Override
+    public boolean isDurationEstimated() {
+      return true;
+    }
+
+    @Override
+    public boolean isDateBased() {
+      return true;
+    }
+
+    @Override
+    public boolean isTimeBased() {
+      return false;
+    }
+
+    @Override
+    public <R extends Temporal> R addTo(R temporal, long amount) {
+      return ChronoUnit.MONTHS.addTo(temporal, amount * 3);
+    }
+
+    @Override
+    public long between(Temporal temporal1Inclusive, Temporal temporal2Exclusive) {
+      return ChronoUnit.MONTHS.between(temporal1Inclusive, temporal2Exclusive) / 3;
+    }
+  }
+}

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/GenericBinaryObjectMapOperation.java

@@ -0,0 +1,113 @@
+package org.enso.table.data.column.operation.map;
+
+import org.enso.base.polyglot.Polyglot_Utils;
+import org.enso.table.data.column.builder.Builder;
+import org.enso.table.data.column.storage.Storage;
+import org.enso.table.data.column.storage.type.AnyObjectType;
+import org.enso.table.error.UnexpectedTypeException;
+import org.graalvm.polyglot.Context;
+
+public abstract class GenericBinaryObjectMapOperation<
+        InputType, InputStorageType extends Storage<InputType>, OutputType>
+    extends MapOperation<InputType, InputStorageType> {
+
+  protected GenericBinaryObjectMapOperation(
+      String name,
+      Class<InputType> inputTypeClass,
+      Class<? extends InputStorageType> inputStorageTypeClass) {
+    super(name);
+    this.inputTypeClass = inputTypeClass;
+    this.inputStorageTypeClass = inputStorageTypeClass;
+  }
+
+  private final Class<InputType> inputTypeClass;
+  private final Class<? extends InputStorageType> inputStorageTypeClass;
+
+  protected abstract Builder createOutputBuilder(int size);
+
+  protected abstract OutputType run(InputType value, InputType other);
+
+  @Override
+  public Storage<?> runMap(
+      InputStorageType storage, Object arg, MapOperationProblemBuilder problemBuilder) {
+    arg = Polyglot_Utils.convertPolyglotValue(arg);
+    if (arg == null) {
+      int n = storage.size();
+      Builder builder = createOutputBuilder(n);
+      builder.appendNulls(n);
+      return builder.seal();
+    } else if (inputTypeClass.isInstance(arg)) {
+      InputType casted = inputTypeClass.cast(arg);
+      int n = storage.size();
+      Builder builder = createOutputBuilder(n);
+      Context context = Context.getCurrent();
+      for (int i = 0; i < n; i++) {
+        if (storage.isNa(i)) {
+          builder.appendNulls(1);
+        } else {
+          OutputType result = run(storage.getItemBoxed(i), casted);
+          builder.appendNoGrow(result);
+        }
+
+        context.safepoint();
+      }
+      return builder.seal();
+    } else {
+      throw new UnexpectedTypeException(
+          "a " + inputTypeClass.getName() + " but got " + arg.getClass().getName());
+    }
+  }
+
+  @Override
+  public Storage<?> runZip(
+      InputStorageType storage, Storage<?> arg, MapOperationProblemBuilder problemBuilder) {
+    if (inputStorageTypeClass.isInstance(arg)) {
+      InputStorageType otherCasted = inputStorageTypeClass.cast(arg);
+      int n = storage.size();
+      Builder builder = createOutputBuilder(n);
+      Context context = Context.getCurrent();
+      for (int i = 0; i < n; ++i) {
+        if (storage.isNa(i) || otherCasted.isNa(i)) {
+          builder.appendNulls(1);
+        } else {
+          InputType left = storage.getItemBoxed(i);
+          InputType right = otherCasted.getItemBoxed(i);
+          OutputType result = run(left, right);
+          builder.append(result);
+        }
+
+        context.safepoint();
+      }
+      return builder.seal();
+    } else if (arg.getType() instanceof AnyObjectType) {
+      // TODO this case may not be needed once #7231 gets implemented
+      int n = storage.size();
+      Builder builder = createOutputBuilder(n);
+      Context context = Context.getCurrent();
+      for (int i = 0; i < n; ++i) {
+        if (storage.isNa(i) || arg.isNa(i)) {
+          builder.appendNulls(1);
+        } else {
+          InputType left = storage.getItemBoxed(i);
+          Object right = arg.getItemBoxed(i);
+          if (inputTypeClass.isInstance(right)) {
+            OutputType result = run(left, inputTypeClass.cast(right));
+            builder.append(result);
+          } else {
+            throw new UnexpectedTypeException(
+                "Got a mixed storage where values were assumed to be of type "
+                    + inputTypeClass.getName()
+                    + ", but got a value of type "
+                    + right.getClass().getName());
+          }
+        }
+
+        context.safepoint();
+      }
+      return builder.seal();
+    } else {
+      throw new UnexpectedTypeException(
+          "a " + inputStorageTypeClass.getName() + " or a mixed storage");
+    }
+  }
+}

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/datetime/DatePartExtractors.java

@@ -0,0 +1,93 @@
+package org.enso.table.data.column.operation.map.datetime;
+
+import java.time.temporal.ChronoField;
+import java.time.temporal.IsoFields;
+import java.time.temporal.Temporal;
+import java.time.temporal.TemporalField;
+import org.enso.table.data.column.operation.map.numeric.GenericUnaryIntegerOp;
+import org.enso.table.data.column.storage.Storage;
+
+public class DatePartExtractors {
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> make_op(String name, TemporalField field) {
+    return new GenericUnaryIntegerOp<>(name) {
+      @Override
+      protected long doGenericOperation(Temporal value) {
+        return value.getLong(field);
+      }
+    };
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> year() {
+    return make_op("year", ChronoField.YEAR);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> quarter() {
+    return new GenericUnaryIntegerOp<>("quarter") {
+      @Override
+      protected long doGenericOperation(Temporal value) {
+        long month = value.get(ChronoField.MONTH_OF_YEAR);
+        return (month - 1) / 3 + 1;
+      }
+    };
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> month() {
+    return make_op("month", ChronoField.MONTH_OF_YEAR);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> week() {
+    return make_op("week", IsoFields.WEEK_OF_WEEK_BASED_YEAR);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> day() {
+    return make_op("day", ChronoField.DAY_OF_MONTH);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> hour() {
+    return make_op("hour", ChronoField.HOUR_OF_DAY);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> minute() {
+    return make_op("minute", ChronoField.MINUTE_OF_HOUR);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> second() {
+    return make_op("second", ChronoField.SECOND_OF_MINUTE);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> millisecond() {
+    return make_op("millisecond", ChronoField.MILLI_OF_SECOND);
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> microsecond() {
+    return new GenericUnaryIntegerOp<>("microsecond") {
+      @Override
+      protected long doGenericOperation(Temporal value) {
+        long micros = value.get(ChronoField.MICRO_OF_SECOND);
+        return micros % 1000;
+      }
+    };
+  }
+
+  public static <T extends Temporal, I extends Storage<T>>
+      GenericUnaryIntegerOp<Temporal, T, I> nanosecond() {
+    return new GenericUnaryIntegerOp<>("nanosecond") {
+      @Override
+      protected long doGenericOperation(Temporal value) {
+        long micros = value.get(ChronoField.NANO_OF_SECOND);
+        return micros % 1000;
+      }
+    };
+  }
+}

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/numeric/DoubleLongMapOpWithSpecialNumericHandling.java

@@ -1,6 +1,8 @@
-package org.enso.table.data.column.operation.map;
+package org.enso.table.data.column.operation.map.numeric;
 
 import java.util.BitSet;
+import org.enso.table.data.column.operation.map.MapOperationProblemBuilder;
+import org.enso.table.data.column.operation.map.UnaryMapOperationWithProblemBuilder;
 import org.enso.table.data.column.storage.numeric.DoubleStorage;
 import org.enso.table.data.column.storage.numeric.LongStorage;
 import org.graalvm.polyglot.Context;

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/numeric/GenericUnaryIntegerOp.java

@@ -0,0 +1,17 @@
+package org.enso.table.data.column.operation.map.numeric;
+
+import org.enso.table.data.column.storage.Storage;
+
+public abstract class GenericUnaryIntegerOp<U, T extends U, I extends Storage<T>>
+    extends UnaryIntegerOp<T, I> {
+  public GenericUnaryIntegerOp(String name) {
+    super(name);
+  }
+
+  protected abstract long doGenericOperation(U value);
+
+  @Override
+  protected long doOperation(T value) {
+    return doGenericOperation(value);
+  }
+}

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/numeric/UnaryDoubleToLongOp.java

@@ -1,6 +1,7 @@
-package org.enso.table.data.column.operation.map;
+package org.enso.table.data.column.operation.map.numeric;
 
 import java.util.BitSet;
+import org.enso.table.data.column.operation.map.UnaryMapOperation;
 import org.enso.table.data.column.storage.numeric.DoubleStorage;
 import org.enso.table.data.column.storage.numeric.LongStorage;
 import org.graalvm.polyglot.Context;

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/numeric/UnaryIntegerOp.java

@@ -1,6 +1,7 @@
-package org.enso.table.data.column.operation.map;
+package org.enso.table.data.column.operation.map.numeric;
 
 import java.util.BitSet;
+import org.enso.table.data.column.operation.map.UnaryMapOperation;
 import org.enso.table.data.column.storage.Storage;
 import org.enso.table.data.column.storage.numeric.LongStorage;
 import org.graalvm.polyglot.Context;

std-bits/table/src/main/java/org/enso/table/data/column/operation/map/numeric/UnaryLongToLongOp.java

@@ -1,6 +1,7 @@
-package org.enso.table.data.column.operation.map;
+package org.enso.table.data.column.operation.map.numeric;
 
 import java.util.BitSet;
+import org.enso.table.data.column.operation.map.UnaryMapOperation;
 import org.enso.table.data.column.storage.numeric.AbstractLongStorage;
 import org.enso.table.data.column.storage.numeric.LongStorage;
 import org.graalvm.polyglot.Context;

std-bits/table/src/main/java/org/enso/table/data/column/storage/datetime/DateStorage.java

@@ -4,7 +4,7 @@ import java.time.LocalDate;
 import org.enso.table.data.column.builder.Builder;
 import org.enso.table.data.column.builder.DateBuilder;
 import org.enso.table.data.column.operation.map.MapOpStorage;
-import org.enso.table.data.column.operation.map.UnaryIntegerOp;
+import org.enso.table.data.column.operation.map.datetime.DatePartExtractors;
 import org.enso.table.data.column.operation.map.datetime.DateTimeIsInOp;
 import org.enso.table.data.column.storage.ObjectStorage;
 import org.enso.table.data.column.storage.SpecializedStorage;
@@ -25,27 +25,11 @@ public final class DateStorage extends SpecializedStorage<LocalDate> {
   private static MapOpStorage<LocalDate, SpecializedStorage<LocalDate>> buildOps() {
     MapOpStorage<LocalDate, SpecializedStorage<LocalDate>> t = ObjectStorage.buildObjectOps();
     t.add(new DateTimeIsInOp<>(LocalDate.class));
-    t.add(
-        new UnaryIntegerOp<>(Maps.YEAR) {
-          @Override
-          protected long doOperation(LocalDate date) {
-            return (long) date.getYear();
-          }
-        });
-    t.add(
-        new UnaryIntegerOp<>(Maps.MONTH) {
-          @Override
-          protected long doOperation(LocalDate date) {
-            return (long) date.getMonthValue();
-          }
-        });
-    t.add(
-        new UnaryIntegerOp<>(Maps.DAY) {
-          @Override
-          protected long doOperation(LocalDate date) {
-            return (long) date.getDayOfMonth();
-          }
-        });
+    t.add(DatePartExtractors.year());
+    t.add(DatePartExtractors.quarter());
+    t.add(DatePartExtractors.month());
+    t.add(DatePartExtractors.week());
+    t.add(DatePartExtractors.day());
     return t;
   }
 

std-bits/table/src/main/java/org/enso/table/data/column/storage/datetime/DateTimeStorage.java

@@ -1,10 +1,13 @@
 package org.enso.table.data.column.storage.datetime;
 
+import java.time.Duration;
 import java.time.ZonedDateTime;
 import org.enso.table.data.column.builder.Builder;
 import org.enso.table.data.column.builder.DateTimeBuilder;
+import org.enso.table.data.column.builder.ObjectBuilder;
+import org.enso.table.data.column.operation.map.GenericBinaryObjectMapOperation;
 import org.enso.table.data.column.operation.map.MapOpStorage;
-import org.enso.table.data.column.operation.map.UnaryIntegerOp;
+import org.enso.table.data.column.operation.map.datetime.DatePartExtractors;
 import org.enso.table.data.column.operation.map.datetime.DateTimeIsInOp;
 import org.enso.table.data.column.storage.ObjectStorage;
 import org.enso.table.data.column.storage.SpecializedStorage;
@@ -27,25 +30,29 @@ public final class DateTimeStorage extends SpecializedStorage<ZonedDateTime> {
     MapOpStorage<ZonedDateTime, SpecializedStorage<ZonedDateTime>> t =
         ObjectStorage.buildObjectOps();
     t.add(new DateTimeIsInOp<>(ZonedDateTime.class));
+    t.add(DatePartExtractors.year());
+    t.add(DatePartExtractors.quarter());
+    t.add(DatePartExtractors.month());
+    t.add(DatePartExtractors.week());
+    t.add(DatePartExtractors.day());
+    t.add(DatePartExtractors.hour());
+    t.add(DatePartExtractors.minute());
+    t.add(DatePartExtractors.second());
+    t.add(DatePartExtractors.millisecond());
+    t.add(DatePartExtractors.microsecond());
+    t.add(DatePartExtractors.nanosecond());
     t.add(
-        new UnaryIntegerOp<>(Maps.YEAR) {
+        new GenericBinaryObjectMapOperation<
+            ZonedDateTime, SpecializedStorage<ZonedDateTime>, Duration>(
+            Maps.SUB, ZonedDateTime.class, DateTimeStorage.class) {
           @Override
-          protected long doOperation(ZonedDateTime date) {
-            return (long) date.getYear();
+          protected Builder createOutputBuilder(int size) {
+            return new ObjectBuilder(size);
           }
-        });
-    t.add(
-        new UnaryIntegerOp<>(Maps.MONTH) {
+
           @Override
-          protected long doOperation(ZonedDateTime date) {
-            return (long) date.getMonthValue();
-          }
-        });
-    t.add(
-        new UnaryIntegerOp<>(Maps.DAY) {
-          @Override
-          protected long doOperation(ZonedDateTime date) {
-            return (long) date.getDayOfMonth();
+          protected Duration run(ZonedDateTime value, ZonedDateTime other) {
+            return Duration.between(other, value);
           }
         });
     return t;

std-bits/table/src/main/java/org/enso/table/data/column/storage/datetime/TimeOfDayStorage.java

@@ -1,9 +1,13 @@
 package org.enso.table.data.column.storage.datetime;
 
+import java.time.Duration;
 import java.time.LocalTime;
 import org.enso.table.data.column.builder.Builder;
+import org.enso.table.data.column.builder.ObjectBuilder;
 import org.enso.table.data.column.builder.TimeOfDayBuilder;
+import org.enso.table.data.column.operation.map.GenericBinaryObjectMapOperation;
 import org.enso.table.data.column.operation.map.MapOpStorage;
+import org.enso.table.data.column.operation.map.datetime.DatePartExtractors;
 import org.enso.table.data.column.operation.map.datetime.DateTimeIsInOp;
 import org.enso.table.data.column.storage.ObjectStorage;
 import org.enso.table.data.column.storage.SpecializedStorage;
@@ -24,6 +28,25 @@ public final class TimeOfDayStorage extends SpecializedStorage<LocalTime> {
   private static MapOpStorage<LocalTime, SpecializedStorage<LocalTime>> buildOps() {
     MapOpStorage<LocalTime, SpecializedStorage<LocalTime>> t = ObjectStorage.buildObjectOps();
     t.add(new DateTimeIsInOp<>(LocalTime.class));
+    t.add(DatePartExtractors.hour());
+    t.add(DatePartExtractors.minute());
+    t.add(DatePartExtractors.second());
+    t.add(DatePartExtractors.millisecond());
+    t.add(DatePartExtractors.microsecond());
+    t.add(DatePartExtractors.nanosecond());
+    t.add(
+        new GenericBinaryObjectMapOperation<LocalTime, SpecializedStorage<LocalTime>, Duration>(
+            Maps.SUB, LocalTime.class, TimeOfDayStorage.class) {
+          @Override
+          protected Builder createOutputBuilder(int size) {
+            return new ObjectBuilder(size);
+          }
+
+          @Override
+          protected Duration run(LocalTime value, LocalTime other) {
+            return Duration.between(other, value);
+          }
+        });
     return t;
   }
 

std-bits/table/src/main/java/org/enso/table/data/column/storage/numeric/AbstractLongStorage.java

@@ -5,11 +5,11 @@ import org.enso.table.data.column.builder.Builder;
 import org.enso.table.data.column.builder.NumericBuilder;
 import org.enso.table.data.column.operation.map.MapOpStorage;
 import org.enso.table.data.column.operation.map.MapOperationProblemBuilder;
-import org.enso.table.data.column.operation.map.UnaryLongToLongOp;
 import org.enso.table.data.column.operation.map.UnaryMapOperation;
 import org.enso.table.data.column.operation.map.numeric.LongBooleanOp;
 import org.enso.table.data.column.operation.map.numeric.LongIsInOp;
 import org.enso.table.data.column.operation.map.numeric.LongNumericOp;
+import org.enso.table.data.column.operation.map.numeric.UnaryLongToLongOp;
 import org.enso.table.data.column.storage.BoolStorage;
 import org.enso.table.data.column.storage.Storage;
 import org.graalvm.polyglot.Context;

std-bits/table/src/main/java/org/enso/table/data/column/storage/numeric/DoubleStorage.java

@@ -4,12 +4,12 @@ import java.util.BitSet;
 import java.util.List;
 import org.enso.table.data.column.builder.Builder;
 import org.enso.table.data.column.builder.NumericBuilder;
-import org.enso.table.data.column.operation.map.DoubleLongMapOpWithSpecialNumericHandling;
 import org.enso.table.data.column.operation.map.MapOpStorage;
 import org.enso.table.data.column.operation.map.MapOperationProblemBuilder;
 import org.enso.table.data.column.operation.map.UnaryMapOperation;
 import org.enso.table.data.column.operation.map.numeric.DoubleBooleanOp;
 import org.enso.table.data.column.operation.map.numeric.DoubleIsInOp;
+import org.enso.table.data.column.operation.map.numeric.DoubleLongMapOpWithSpecialNumericHandling;
 import org.enso.table.data.column.operation.map.numeric.DoubleNumericOp;
 import org.enso.table.data.column.storage.BoolStorage;
 import org.enso.table.data.column.storage.Storage;

std-bits/table/src/main/java/org/enso/table/error/UnexpectedTypeException.java

@@ -1,6 +1,11 @@
 package org.enso.table.error;
 
-/** An error thrown when a type error is encountered. */
+/**
+ * An error thrown when a type error is encountered.
+ *
+ * <p>This is an internal error of the Table library and any time it is thrown indicates a bug.
+ * Normally, the types should be checked before being passed to a vectorized operation.
+ */
 public class UnexpectedTypeException extends RuntimeException {
   private final String expected;
 

test/Table_Tests/src/Common_Table_Operations/Date_Time_Spec.enso

@@ -9,7 +9,7 @@ from Standard.Database.Errors import Unsupported_Database_Operation
 from Standard.Test import Test, Problems
 import Standard.Test.Extensions
 
-from project.Common_Table_Operations.Util import run_default_backend
+from project.Common_Table_Operations.Util import all
 
 main = run_default_backend spec
 
@@ -42,50 +42,45 @@ spec setup =
             named_zone = Time_Zone.parse "US/Hawaii"
             dt3 = Date_Time.new 2019 11 23 4 5 6 zone=named_zone
 
-            to_utc dt = dt.at_zone Time_Zone.utc
             dates = [dt1, dt2, dt3]
             xs = [1, 2, 3]
             table = table_builder [["C", dates], ["X", xs]]
             table.at "C" . value_type . should_equal Value_Type.Date_Time
-            ## We compare the timestamps converted to UTC.
-               This ensures that the value we are getting back represents the
-               exact same instant in time as the one we put in.
-
-               We cannot guarantee that time time _zone_ itself will be the same
-               - for example Postgres stores all timestamps in UTC, regardless
-               of what timezone they were in at input.
-            table.at "C" . to_vector . map to_utc . should_equal (dates.map to_utc)
+            table.at "C" . to_vector . should_equal_tz_agnostic dates
             table.at "X" . to_vector . should_equal xs
 
     Test.group prefix+"Date-Time operations" pending=pending_datetime <|
+        dates = table_builder [["A", [Date.new 2020 12 31, Date.new 2024 2 29, Date.new 1990 1 1, Nothing]], ["X", [2020, 29, 1, 100]]]
+        times = table_builder [["A", [Time_Of_Day.new 23 59 59 millisecond=567 nanosecond=123, Time_Of_Day.new 2 30 44 nanosecond=1002000, Time_Of_Day.new 0 0 0, Nothing]], ["X", [2020, 29, 1, 100]]]
+        datetimes = table_builder [["A", [Date_Time.new 2020 12 31 23 59 59 millisecond=567 nanosecond=123, Date_Time.new 2024 2 29 2 30 44 nanosecond=1002000, Date_Time.new 1990 1 1 0 0 0, Nothing]], ["X", [2020, 29, 1, 100]]]
         Test.specify "should allow to get the year/month/day of a Date" <|
-            t = table_builder [["A", [Date.new 2020 12 31, Date.new 2024 2 29, Date.new 1990 1 1, Nothing]], ["X", [2020, 29, 1, 100]]]
-
-            t.at "A" . year . to_vector . should_equal [2020, 2024, 1990, Nothing]
-            t.at "A" . month . to_vector . should_equal [12, 2, 1, Nothing]
-            t.at "A" . day . to_vector . should_equal [31, 29, 1, Nothing]
-            [t.at "A" . year, t.at "A" . month, t.at "A" . day].each c->
+            t = dates
+            a = t.at "A"
+            a.year . to_vector . should_equal [2020, 2024, 1990, Nothing]
+            a.month . to_vector . should_equal [12, 2, 1, Nothing]
+            a.day . to_vector . should_equal [31, 29, 1, Nothing]
+            [a.year, a.month, a.day].each c->
                 Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
                     c.value_type.is_integer.should_be_true
                 c.value_type.is_integer.should_be_true
 
-            ((t.at "A" . year) == (t.at "X")).to_vector . should_equal [True, False, False, Nothing]
-            ((t.at "A" . month) == (t.at "X")).to_vector . should_equal [False, False, True, Nothing]
-            ((t.at "A" . day) == (t.at "X")).to_vector . should_equal [False, True, True, Nothing]
+            ((a.year) == (t.at "X")).to_vector . should_equal [True, False, False, Nothing]
+            ((a.month) == (t.at "X")).to_vector . should_equal [False, False, True, Nothing]
+            ((a.day) == (t.at "X")).to_vector . should_equal [False, True, True, Nothing]
 
         Test.specify "should allow to get the year/month/day of a Date_Time" <|
-            t = table_builder [["A", [Date_Time.new 2020 12 31 23 59 59, Date_Time.new 2024 2 29 2 30 44, Date_Time.new 1990 1 1 0 0 0, Nothing]], ["X", [2020, 29, 1, 100]]]
-
-            t.at "A" . year . to_vector . should_equal [2020, 2024, 1990, Nothing]
-            t.at "A" . month . to_vector . should_equal [12, 2, 1, Nothing]
-            t.at "A" . day . to_vector . should_equal [31, 29, 1, Nothing]
-            [t.at "A" . year, t.at "A" . month, t.at "A" . day].each c->
+            t = datetimes
+            a = t.at "A"
+            a.year . to_vector . should_equal [2020, 2024, 1990, Nothing]
+            a.month . to_vector . should_equal [12, 2, 1, Nothing]
+            a.day . to_vector . should_equal [31, 29, 1, Nothing]
+            [a.year, a.month, a.day].each c->
                 Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
                     c.value_type.is_integer.should_be_true
 
-            ((t.at "A" . year) == (t.at "X")).to_vector . should_equal [True, False, False, Nothing]
-            ((t.at "A" . month) == (t.at "X")).to_vector . should_equal [False, False, True, Nothing]
-            ((t.at "A" . day) == (t.at "X")).to_vector . should_equal [False, True, True, Nothing]
+            ((a.year) == (t.at "X")).to_vector . should_equal [True, False, False, Nothing]
+            ((a.month) == (t.at "X")).to_vector . should_equal [False, False, True, Nothing]
+            ((a.day) == (t.at "X")).to_vector . should_equal [False, True, True, Nothing]
 
         Test.specify "should allow to evaluate expressions with year/month/day" <|
             t = table_builder [["A", [Date.new 2020 12 31, Date.new 2024 2 29, Date.new 1990 1 1, Nothing]], ["X", [0, 2, 1, 100]], ["B", [Date_Time.new 2020 10 31 23 59 59, Date_Time.new 2024 4 29 2 30 44, Date_Time.new 1990 10 1 0 0 0, Nothing]]]
@@ -94,13 +89,74 @@ spec setup =
                 c.value_type.is_integer.should_be_true
             c.to_vector . should_equal [(2020 + 0 + 31 * 10), (2024 + 2 + 29 * 4), (1990 + 1 + 1 * 10), Nothing]
 
-        Test.specify "should report a type error if year/month/day is invoked on a non-date column" <|
-            t = table_builder [["A", [1, 2, 3]], ["B", ["a", "b", "c"]], ["C", [True, False, True]]]
-            r1 = t.at "A" . year
-            r1.should_fail_with Invalid_Value_Type
-            r1.catch . to_display_text . should_start_with "Expected type Date or Date_Time, but got a column [A] of type Integer"
-            t.at "B" . month . should_fail_with Invalid_Value_Type
-            t.at "C" . day . should_fail_with Invalid_Value_Type
+        Test.specify "should allow to get hour/minute/second of a Time_Of_Day" <|
+            a = times.at "A"
+            a.hour . to_vector . should_equal [23, 2, 0, Nothing]
+            a.minute . to_vector . should_equal [59, 30, 0, Nothing]
+            a.second . to_vector . should_equal [59, 44, 0, Nothing]
+
+            a.date_part Time_Period.Hour . to_vector . should_equal [23, 2, 0, Nothing]
+            a.date_part Time_Period.Minute . to_vector . should_equal [59, 30, 0, Nothing]
+            a.date_part Time_Period.Second . to_vector . should_equal [59, 44, 0, Nothing]
+
+            [a.hour, a.minute, a.second, a.date_part Time_Period.Hour, a.date_part Time_Period.Minute, a.date_part Time_Period.Second].each c->
+                Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
+                    c.value_type.is_integer.should_be_true
+
+        Test.specify "should allow to get hour/minute/second of a Date_Time" <|
+            a = datetimes.at "A"
+            a.hour . to_vector . should_equal [23, 2, 0, Nothing]
+            a.minute . to_vector . should_equal [59, 30, 0, Nothing]
+            a.second . to_vector . should_equal [59, 44, 0, Nothing]
+
+            a.date_part Time_Period.Hour . to_vector . should_equal [23, 2, 0, Nothing]
+            a.date_part Time_Period.Minute . to_vector . should_equal [59, 30, 0, Nothing]
+            a.date_part Time_Period.Second . to_vector . should_equal [59, 44, 0, Nothing]
+
+            [a.hour, a.minute, a.second, a.date_part Time_Period.Hour, a.date_part Time_Period.Minute, a.date_part Time_Period.Second].each c->
+                Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
+                    c.value_type.is_integer.should_be_true
+
+        Test.specify "should allow to get millisecond/nanosecond of Time_Of_Day through date_part" <|
+            a = times.at "A"
+            a.date_part Time_Period.Second . to_vector . should_equal      [59, 44, 0, Nothing]
+            a.date_part Time_Period.Millisecond . to_vector . should_equal [567, 1, 0, Nothing]
+            a.date_part Time_Period.Microsecond . to_vector . should_equal [0,   2, 0, Nothing]
+            case setup.test_selection.supports_nanoseconds_in_time of
+                True ->
+                    a.date_part Time_Period.Nanosecond . to_vector . should_equal  [123, 0, 0, Nothing]
+                False ->
+                    a.date_part Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+
+            [a.date_part Time_Period.Second, a.date_part Time_Period.Millisecond, a.date_part Time_Period.Microsecond, a.date_part Time_Period.Nanosecond].each c->
+                Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
+                    c.value_type.is_integer.should_be_true
+
+        Test.specify "should allow to get week/quarter of Date through date_part" <|
+            a = dates.at "A"
+            a.date_part Date_Period.Quarter . to_vector . should_equal [4, 1, 1, Nothing]
+            a.date_part Date_Period.Week . to_vector . should_equal [53, 9, 1, Nothing]
+
+            [a.date_part Date_Period.Quarter, a.date_part Date_Period.Week].each c->
+                Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
+                    c.value_type.is_integer.should_be_true
+
+        Test.specify "should allow to get various date_part of Date_Time" <|
+            a = datetimes.at "A"
+            a.date_part Date_Period.Quarter . to_vector . should_equal [4, 1, 1, Nothing]
+            a.date_part Date_Period.Week . to_vector . should_equal [53, 9, 1, Nothing]
+            a.date_part Time_Period.Millisecond . to_vector . should_equal [567, 1, 0, Nothing]
+            a.date_part Time_Period.Microsecond . to_vector . should_equal [0,   2, 0, Nothing]
+            case setup.test_selection.supports_nanoseconds_in_time of
+                True ->
+                    a.date_part Time_Period.Nanosecond . to_vector . should_equal  [123, 0, 0, Nothing]
+                False ->
+                    a.date_part Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+
+            [a.date_part Date_Period.Quarter, a.date_part Date_Period.Week, a.date_part Time_Period.Second, a.date_part Time_Period.Millisecond, a.date_part Time_Period.Microsecond, a.date_part Time_Period.Nanosecond].each c->
+                Test.with_clue "The column "+c.name+" value type ("+c.value_type.to_display_text+") should be an integer: " <|
+                    c.value_type.is_integer.should_be_true
+
 
         Test.specify "should allow to compare dates" <|
             t = table_builder [["X", [Date.new 2021 12 3]], ["Y", [Date.new 2021 12 5]]]
@@ -126,16 +182,303 @@ spec setup =
                 op (t.at "X") (t.at "Y") . to_vector . should_succeed
                 op (t.at "X") (Time_Of_Day.new 12 30 0) . to_vector . should_succeed
 
-        Test.specify "should not allow to mix" <|
+        Test.specify "should not allow to mix types in ordering comparisons" <|
             t = table_builder [["X", [Date.new 2021 12 3]], ["Y", [Date_Time.new 2021 12 5 12 30 0]], ["Z", [Time_Of_Day.new 12 30 0]]]
 
             [(<), (<=), (>), (>=)].each op->
                 op (t.at "X") (t.at "Y") . should_fail_with Invalid_Value_Type
                 op (t.at "X") (t.at "Z") . should_fail_with Invalid_Value_Type
 
+        if setup.test_selection.supports_time_duration then
+            Test.specify "should allow to subtract two Dates" <|
+                t = table_builder [["X", [Date.new 2021 11 3]], ["Y", [Date.new 2021 12 5]]]
+
+                ((t.at "Y") - (t.at "X")) . to_vector . should_equal [Period.new months=1 days=2]
+                ((t.at "Y") - (Date.new 2020 12 5)) . to_vector . should_equal [Period.new years=1]
+
+            Test.specify "should allow to subtract two Date_Times" <|
+                dx = Date_Time.new 2021 11 30 10 15 0
+                t = table_builder [["X", [dx]], ["Y", [Date_Time.new 2021 12 5 12 30 20]]]
+
+                hours = 2 + 24 * 5
+                diff = Duration.new hours=hours minutes=15 seconds=20
+                ((t.at "Y") - (t.at "X")) . to_vector . should_equal [diff]
+                ((t.at "Y") - dx) . to_vector . should_equal [diff]
+
+            Test.specify "should allow to subtract two Time_Of_Days" <|
+                t = table_builder [["X", [Time_Of_Day.new 10 15 0, Time_Of_Day.new 1 0 0]], ["Y", [Time_Of_Day.new 12 30 20, Time_Of_Day.new 0 0 0]]]
+
+                ((t.at "Y") - (t.at "X")) . to_vector . should_equal [Duration.new hours=2 minutes=15 seconds=20, Duration.new hours=(-1) minutes=0 seconds=0]
+                ((t.at "Y") - (Time_Of_Day.new 0 0 0)) . to_vector . should_equal [Duration.new hours=12 minutes=30 seconds=20, Duration.zero]
+
+        if setup.test_selection.supports_time_duration.not then
+            Test.specify "should report unsupported operation for subtracting date/time" <|
+                t1 = table_builder [["X", [Date.new 2021 11 3]], ["Y", [Date.new 2021 12 5]]]
+                t2 = table_builder [["X", [Date_Time.new 2021 11 3 10 15 0]], ["Y", [Date_Time.new 2021 12 5 12 30 20]]]
+                t3 = table_builder [["X", [Time_Of_Day.new 10 15 0, Time_Of_Day.new 1 0 0]], ["Y", [Time_Of_Day.new 12 30 20, Time_Of_Day.new 0 0 0]]]
+
+                ((t1.at "Y") - (t1.at "X")) . should_fail_with Unsupported_Database_Operation
+                ((t1.at "Y") - (Date.new 2020 12 5)) . should_fail_with Unsupported_Database_Operation
+                ((t2.at "Y") - (t2.at "X")) . should_fail_with Unsupported_Database_Operation
+                ((t2.at "Y") - (Date_Time.new 2020 12 5 10 15 0)) . should_fail_with Unsupported_Database_Operation
+                ((t3.at "Y") - (t3.at "X")) . should_fail_with Unsupported_Database_Operation
+                ((t3.at "Y") - (Time_Of_Day.new 0 0 0)) . should_fail_with Unsupported_Database_Operation
+
+        Test.specify "should report an Invalid_Value_Type error when subtracting mixed date/time types" <|
+            t = table_builder [["X", [Date.new 2021 11 3]], ["Y", [Date_Time.new 2021 12 5 12 30 0]], ["Z", [Time_Of_Day.new 12 30 0]]]
+
+            ((t.at "Y") - (t.at "X")) . should_fail_with Invalid_Value_Type
+            ((t.at "Y") - (Time_Of_Day.new 12 30 0)) . should_fail_with Invalid_Value_Type
+            ((t.at "X") - (t.at "Z")) . should_fail_with Invalid_Value_Type
+            ((t.at "X") - (Date_Time.new 2021 12 5 12 30 0)) . should_fail_with Invalid_Value_Type
+            ((t.at "Z") - (t.at "Y")) . should_fail_with Invalid_Value_Type
+            ((t.at "Z") - (Date.new 2021 11 3)) . should_fail_with Invalid_Value_Type
+
+        Test.specify "should allow computing a SQL-like difference" <|
+            t1 = table_builder [["X", [Date.new 2021 11 3]], ["Y", [Date.new 2021 12 5]]]
+
+            (t1.at "X").date_diff (t1.at "Y") Date_Period.Day . to_vector . should_equal [32]
+            (t1.at "Y").date_diff (t1.at "X") Date_Period.Day . to_vector . should_equal [-32]
+            (t1.at "X").date_diff (Date.new 2021 11 3) Date_Period.Day . to_vector . should_equal [0]
+
+            (t1.at "X").date_diff (t1.at "Y") Date_Period.Month . to_vector . should_equal [1]
+            (t1.at "X").date_diff (Date.new 2021 12 1) Date_Period.Month . to_vector . should_equal [0]
+            (t1.at "X").date_diff (Date.new 2020 12 1) Date_Period.Month . to_vector . should_equal [-11]
+
+            (t1.at "X").date_diff (t1.at "Y") Date_Period.Quarter . to_vector . should_equal [0]
+            (t1.at "X").date_diff (Date.new 2021 5 1) Date_Period.Quarter . to_vector . should_equal [-2]
+            (t1.at "X").date_diff (Date.new 2023 7 1) Date_Period.Quarter . to_vector . should_equal [6]
+
+            (t1.at "X").date_diff (t1.at "Y") Date_Period.Year . to_vector . should_equal [0]
+            (t1.at "X").date_diff (Date.new 2021 12 1) Date_Period.Year . to_vector . should_equal [0]
+            (t1.at "X").date_diff (Date.new 2020 10 1) Date_Period.Year . to_vector . should_equal [-1]
+
+            # Ensure months of varying length (e.g. February) are still counted right.
+            t1_2 = table_builder [["X", [Date.new 2021 01 02]]]
+            (t1_2 . at "X").date_diff (Date.new 2021 03 02) Date_Period.Day . to_vector . should_equal [59]
+            (t1_2 . at "X").date_diff (Date.new 2021 03 02) Date_Period.Month . to_vector . should_equal [2]
+            (t1_2 . at "X").date_diff (Date.new 2021 03 01) Date_Period.Day . to_vector . should_equal [58]
+            (t1_2 . at "X").date_diff (Date.new 2021 03 01) Date_Period.Month . to_vector . should_equal [1]
+
+            # We do allow the `Time_Period.Day` as a kind of alias for `Date_Period.Day` here.
+            (t1.at "X").date_diff (t1.at "Y") Time_Period.Day . to_vector . should_equal [32]
+            (t1.at "X").date_diff (t1.at "Y") Time_Period.Hour . should_fail_with Illegal_Argument
+
+            t2 = table_builder [["X", [Date_Time.new 2021 11 3 10 15 0]], ["Y", [Date_Time.new 2021 12 5 12 30 20]]]
+
+            (t2.at "X").date_diff (t2.at "Y") Date_Period.Day . to_vector . should_equal [32]
+            (t2.at "Y").date_diff (t2.at "X") Date_Period.Day . to_vector . should_equal [-32]
+            (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 15 0) Date_Period.Day . to_vector . should_equal [0]
+
+            (t2.at "X").date_diff (t2.at "Y") Date_Period.Month . to_vector . should_equal [1]
+            (t2.at "X").date_diff (Date_Time.new 2021 12 1 10 15 0) Date_Period.Month . to_vector . should_equal [0]
+
+            (t2.at "X").date_diff (t2.at "Y") Date_Period.Year . to_vector . should_equal [0]
+            (t2.at "X").date_diff (Date_Time.new 2031 12 1 10 15 0) Date_Period.Year . to_vector . should_equal [10]
+
+            (t2.at "X").date_diff (t2.at "Y") Time_Period.Day . to_vector . should_equal [32]
+
+            (t2.at "X").date_diff (t2.at "Y") Time_Period.Hour . to_vector . should_equal [770]
+            (t2.at "X").date_diff (Date_Time.new 2021 11 3 12 15 0) Time_Period.Hour . to_vector . should_equal [2]
+
+            (t2.at "X").date_diff (t2.at "Y") Time_Period.Minute . to_vector . should_equal [46215]
+            (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 45 0) Time_Period.Minute . to_vector . should_equal [30]
+
+            (t2.at "X").date_diff (t2.at "Y") Time_Period.Second . to_vector . should_equal [2772920]
+            (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 15 30) Time_Period.Second . to_vector . should_equal [30]
+
+            (t2.at "X").date_diff (t2.at "Y") Time_Period.Millisecond . to_vector . should_equal [2772920000]
+            (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 15 30 123) Time_Period.Millisecond . to_vector . should_equal [30123]
+
+            (t2.at "X").date_diff (t2.at "Y") Time_Period.Microsecond . to_vector . should_equal [2772920000000]
+            (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 15 30 123 456) Time_Period.Microsecond . to_vector . should_equal [30123456]
+
+            case setup.test_selection.supports_nanoseconds_in_time of
+                True ->
+                    (t2.at "X").date_diff (t2.at "Y") Time_Period.Nanosecond . to_vector . should_equal [2772920000000000]
+                    (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 15 30 123 456 789) Time_Period.Nanosecond . to_vector . should_equal [30123456789]
+                False ->
+                    (t2.at "X").date_diff (t2.at "Y") Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+                    (t2.at "X").date_diff (Date_Time.new 2021 11 3 10 15 30 123 456 789) Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+
+            t3 = table_builder [["X", [Time_Of_Day.new 10 15 0]], ["Y", [Time_Of_Day.new 12 30 20]]]
+
+            # There is no default period:
+            (t3.at "X").date_diff (t3.at "Y") . should_be_a Function
+            (t3.at "X").date_diff (t3.at "Y") Date_Period.Month . should_fail_with Illegal_Argument
+
+            # This will always be 0, should it be allowed?
+            (t3.at "X").date_diff (t3.at "Y") Time_Period.Day . should_fail_with Illegal_Argument
+
+            (t3.at "X").date_diff (t3.at "Y") Time_Period.Hour . to_vector . should_equal [2]
+            (t3.at "X").date_diff (Time_Of_Day.new 9 15 0) Time_Period.Hour . to_vector . should_equal [-1]
+
+            (t3.at "X").date_diff (t3.at "Y") Time_Period.Minute . to_vector . should_equal [135]
+            (t3.at "X").date_diff (Time_Of_Day.new 10 04 0) Time_Period.Minute . to_vector . should_equal [-11]
+
+            (t3.at "X").date_diff (t3.at "Y") Time_Period.Second . to_vector . should_equal [8120]
+            (t3.at "X").date_diff (Time_Of_Day.new 10 15 12) Time_Period.Second . to_vector . should_equal [12]
+
+            (t3.at "X").date_diff (t3.at "Y") Time_Period.Millisecond . to_vector . should_equal [8120*1000]
+            (t3.at "X").date_diff (Time_Of_Day.new 10 15 12 34) Time_Period.Millisecond . to_vector . should_equal [12034]
+
+            (t3.at "X").date_diff (t3.at "Y") Time_Period.Microsecond . to_vector . should_equal [8120*1000*1000]
+            (t3.at "X").date_diff (Time_Of_Day.new 10 15 12 34 56) Time_Period.Microsecond . to_vector . should_equal [12034056]
+
+            case setup.test_selection.supports_nanoseconds_in_time of
+                True ->
+                    (t3.at "X").date_diff (t3.at "Y") Time_Period.Nanosecond . to_vector . should_equal [8120*1000*1000*1000]
+                    (t3.at "X").date_diff (Time_Of_Day.new 10 15 12 34 56 78) Time_Period.Nanosecond . to_vector . should_equal [12034056078]
+                False ->
+                    (t3.at "X").date_diff (t3.at "Y") Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+                    (t3.at "X").date_diff (Time_Of_Day.new 10 15 12 34 56 78) Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+
+        Test.specify "date_diff should return integers" <|
+            t = table_builder [["X", [Date.new 2021 01 31]], ["Y", [Time_Of_Day.new 12 30 20]], ["Z", [Date_Time.new 2021 12 5 12 30 20]]]
+
+            time_periods = [Time_Period.Hour, Time_Period.Minute, Time_Period.Second]
+            date_periods = [Date_Period.Day, Date_Period.Week, Date_Period.Month, Date_Period.Quarter, Date_Period.Year]
+
+            date_periods.each p->
+                (t.at "X").date_diff (Date.new 2021 12 05) p . value_type . is_integer . should_be_true
+
+            time_periods.each p->
+                (t.at "Y").date_diff (Time_Of_Day.new 01 02) p . value_type . is_integer . should_be_true
+
+            (date_periods+time_periods).each p->
+                (t.at "Z").date_diff (Date_Time.new 2021 12 05 01 02) p . value_type . is_integer . should_be_true
+
+        Test.specify "should not allow mixing types in date_diff" <|
+            t = table_builder [["X", [Date.new 2021 01 31]], ["Y", [Time_Of_Day.new 12 30 20]], ["Z", [Date_Time.new 2021 12 5 12 30 20]]]
+            (t.at "X").date_diff (t.at "Y") Date_Period.Day . should_fail_with Invalid_Value_Type
+            (t.at "Z").date_diff (t.at "X") Date_Period.Day . should_fail_with Invalid_Value_Type
+            (t.at "Y").date_diff (t.at "Z") Time_Period.Hour . should_fail_with Invalid_Value_Type
+
+            r1 = (t.at "X").date_diff (Date_Time.new 2021 12 5 12 30 20) Date_Period.Day
+            r1.should_fail_with Invalid_Value_Type
+            r1.catch.expected.to_text . should_equal "Date"
+            (t.at "Y").date_diff (Date.new 2021 12 5) Date_Period.Day . should_fail_with Invalid_Value_Type
+            (t.at "Z").date_diff (Time_Of_Day.new 12 30 20) Time_Period.Hour . should_fail_with Invalid_Value_Type
+
+        Test.specify "should allow an SQL-like shift" <|
+            t1 = table_builder [["X", [Date.new 2021 01 31, Date.new 2021 01 01, Date.new 2021 12 31]], ["Y", [5, -1, 0]]]
+            (t1.at "X").date_add (t1.at "Y") Date_Period.Day . to_vector . should_equal [Date.new 2021 02 05, Date.new 2020 12 31, Date.new 2021 12 31]
+            (t1.at "X").date_add -1 Date_Period.Day . to_vector . should_equal [Date.new 2021 01 30, Date.new 2020 12 31, Date.new 2021 12 30]
+            (t1.at "X").date_add (t1.at "Y") Date_Period.Month . to_vector . should_equal [Date.new 2021 06 30, Date.new 2020 12 01, Date.new 2021 12 31]
+            (t1.at "X").date_add 1 Date_Period.Month . to_vector . should_equal [Date.new 2021 02 28, Date.new 2021 02 01, Date.new 2022 01 31]
+            (t1.at "X").date_add (t1.at "Y") Date_Period.Year . to_vector . should_equal [Date.new 2026 01 31, Date.new 2020 01 01, Date.new 2021 12 31]
+            (t1.at "X").date_add 1 Date_Period.Year . to_vector . should_equal [Date.new 2022 01 31, Date.new 2022 01 01, Date.new 2022 12 31]
+
+            (t1.at "X").date_add (t1.at "Y") Date_Period.Week . to_vector . should_equal [Date.new 2021 03 07, Date.new 2020 12 25, Date.new 2021 12 31]
+            (t1.at "X").date_add 1 Date_Period.Week . to_vector . should_equal [Date.new 2021 02 07, Date.new 2021 01 08, Date.new 2022 01 07]
+            (t1.at "X").date_add (t1.at "Y") Date_Period.Quarter . to_vector . should_equal [Date.new 2022 04 30, Date.new 2020 10 01, Date.new 2021 12 31]
+            (t1.at "X").date_add 1 Date_Period.Quarter . to_vector . should_equal [Date.new 2021 04 30, Date.new 2021 04 01, Date.new 2022 03 31]
+
+            (t1.at "X").date_add 1 Time_Period.Hour . should_fail_with Illegal_Argument
+            # Will accept Time_Period.Day as alias of Date_Period.Day
+            (t1.at "X").date_add 1 Time_Period.Day . to_vector . should_equal [Date.new 2021 02 01, Date.new 2021 01 02, Date.new 2022 01 01]
+
+            t2 = table_builder [["X", [Date_Time.new 2021 01 31 12 30 0, Date_Time.new 2021 01 01 12 30 0, Date_Time.new 2021 12 31 12 30 0]], ["Y", [5, -1, 0]]]
+            (t2.at "X").date_add (t2.at "Y") Date_Period.Day . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 02 05 12 30 0, Date_Time.new 2020 12 31 12 30 0, Date_Time.new 2021 12 31 12 30 0]
+            (t2.at "X").date_add -1 Time_Period.Day . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 30 12 30 0, Date_Time.new 2020 12 31 12 30 0, Date_Time.new 2021 12 30 12 30 0]
+            (t2.at "X").date_add (t2.at "Y") Date_Period.Month . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 06 30 12 30 0, Date_Time.new 2020 12 01 12 30 0, Date_Time.new 2021 12 31 12 30 0]
+            (t2.at "X").date_add 1 Date_Period.Month . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 02 28 12 30 0, Date_Time.new 2021 02 01 12 30 0, Date_Time.new 2022 01 31 12 30 0]
+            (t2.at "X").date_add (t2.at "Y") Date_Period.Year . to_vector . should_equal_tz_agnostic [Date_Time.new 2026 01 31 12 30 0, Date_Time.new 2020 01 01 12 30 0, Date_Time.new 2021 12 31 12 30 0]
+            (t2.at "X").date_add 1 Date_Period.Year . to_vector . should_equal_tz_agnostic [Date_Time.new 2022 01 31 12 30 0, Date_Time.new 2022 01 01 12 30 0, Date_Time.new 2022 12 31 12 30 0]
+
+            (t2.at "X").date_add (t2.at "Y") Time_Period.Hour . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 17 30 0, Date_Time.new 2021 01 01 11 30 0, Date_Time.new 2021 12 31 12 30 0]
+            (t2.at "X").date_add 1 Time_Period.Hour . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 13 30 0, Date_Time.new 2021 01 01 13 30 0, Date_Time.new 2021 12 31 13 30 0]
+            (t2.at "X").date_add (t2.at "Y") Time_Period.Minute . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 12 35 0, Date_Time.new 2021 01 01 12 29 0, Date_Time.new 2021 12 31 12 30 0]
+            (t2.at "X").date_add 1 Time_Period.Minute . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 12 31 0, Date_Time.new 2021 01 01 12 31 0, Date_Time.new 2021 12 31 12 31 0]
+            (t2.at "X").date_add (t2.at "Y") Time_Period.Second . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 12 30 5, Date_Time.new 2021 01 01 12 29 59, Date_Time.new 2021 12 31 12 30 0]
+            (t2.at "X").date_add 1 Time_Period.Second . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 12 30 1, Date_Time.new 2021 01 01 12 30 1, Date_Time.new 2021 12 31 12 30 1]
+            (t2.at "X").date_add 1 Time_Period.Millisecond . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 12 30 millisecond=1, Date_Time.new 2021 01 01 12 30 millisecond=1, Date_Time.new 2021 12 31 12 30 millisecond=1]
+            (t2.at "X").date_add 1 Time_Period.Microsecond . to_vector . should_equal_tz_agnostic [Date_Time.new 2021 01 31 12 30 microsecond=1, Date_Time.new 2021 01 01 12 30 microsecond=1, Date_Time.new 2021 12 31 12 30 microsecond=1]
+            case setup.test_selection.supports_nanoseconds_in_time of
+                True ->
+                    (t2.at "X").date_add 1 Time_Period.Nanosecond . to_vector . should_equal [Date_Time.new 2021 01 31 12 30 nanosecond=1, Date_Time.new 2021 01 01 12 30 nanosecond=1, Date_Time.new 2021 12 31 12 30 nanosecond=1]
+                False ->
+                    (t2.at "X").date_add 1 Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+
+            t3 = table_builder [["X", [Time_Of_Day.new 12 30 0, Time_Of_Day.new 23 45 0, Time_Of_Day.new 1 30 0]], ["Y", [5, -1, 0]]]
+
+            (t3.at "X").date_add (t3.at "Y") Time_Period.Hour . to_vector . should_equal [Time_Of_Day.new 17 30 0, Time_Of_Day.new 22 45 0, Time_Of_Day.new 1 30 0]
+            (t3.at "X").date_add 1 Time_Period.Hour . to_vector . should_equal [Time_Of_Day.new 13 30 0, Time_Of_Day.new 0 45 0, Time_Of_Day.new 2 30 0]
+            (t3.at "X").date_add (t3.at "Y") Time_Period.Minute . to_vector . should_equal [Time_Of_Day.new 12 35 0, Time_Of_Day.new 23 44 0, Time_Of_Day.new 1 30 0]
+            (t3.at "X").date_add 1 Time_Period.Minute . to_vector . should_equal [Time_Of_Day.new 12 31 0, Time_Of_Day.new 23 46 0, Time_Of_Day.new 1 31 0]
+            (t3.at "X").date_add (t3.at "Y") Time_Period.Second . to_vector . should_equal [Time_Of_Day.new 12 30 5, Time_Of_Day.new 23 44 59, Time_Of_Day.new 1 30 0]
+            (t3.at "X").date_add 1 Time_Period.Second . to_vector . should_equal [Time_Of_Day.new 12 30 1, Time_Of_Day.new 23 45 1, Time_Of_Day.new 1 30 1]
+            (t3.at "X").date_add 1 Time_Period.Millisecond . to_vector . should_equal [Time_Of_Day.new 12 30 millisecond=1, Time_Of_Day.new 23 45 millisecond=1, Time_Of_Day.new 1 30 millisecond=1]
+            (t3.at "X").date_add 1 Time_Period.Microsecond . to_vector . should_equal [Time_Of_Day.new 12 30 microsecond=1, Time_Of_Day.new 23 45 microsecond=1, Time_Of_Day.new 1 30 microsecond=1]
+            case setup.test_selection.supports_nanoseconds_in_time of
+                True ->
+                    (t3.at "X").date_add 1 Time_Period.Nanosecond . to_vector . should_equal [Time_Of_Day.new 12 30 nanosecond=1, Time_Of_Day.new 23 45 nanosecond=1, Time_Of_Day.new 1 30 nanosecond=1]
+                False ->
+                    (t3.at "X").date_add 1 Time_Period.Nanosecond . should_fail_with Unsupported_Database_Operation
+
+            # No sense to shift Time_Of_Day by days either or by a Date_Period
+            (t3.at "X").date_add (t3.at "Y") Time_Period.Day . to_vector . should_fail_with Illegal_Argument
+            (t3.at "X").date_add 1 Date_Period.Month . to_vector . should_fail_with Illegal_Argument
+
+            # There is no default period.
+            (t1.at "X").date_add (t1.at "Y") . should_be_a Function
+
+        Test.specify "should check shift_amount type in date_add" <|
+            t = table_builder [["X", [Date.new 2021 01 31]]]
+            t.at "X" . date_add "text" Date_Period.Day . should_fail_with Invalid_Value_Type
+
+        Test.specify "date_diff and date_add should work correctly with DST" <|
+            zone = Time_Zone.parse "Europe/Warsaw"
+            dt1 = Date_Time.new 2023 03 26 00 30 00 zone=zone
+            t = table_builder [["X", [dt1]]]
+            x = t.at "X"
+
+            # +24h will shift 1 day and 1 hour, because they 26th of March has only 23 hours within it
+            x.date_add 24 Time_Period.Hour . to_vector . should_equal_tz_agnostic [Date_Time.new 2023 03 27 01 30 00 zone=zone]
+
+            # But 1 day date shift will shift 1 day, keeping the time, even if that particular day is only 23 hours.
+            x.date_add 1 Date_Period.Day . to_vector . should_equal_tz_agnostic [Date_Time.new 2023 03 27 00 30 00 zone=zone]
+            # Time_Period.Day will shift by 24 hours.
+            x.date_add 1 Time_Period.Day . to_vector . should_equal_tz_agnostic [Date_Time.new 2023 03 27 01 30 00 zone=zone]
+
+            dt2 = Date_Time.new 2023 03 27 00 30 00 zone=zone
+            x.date_diff dt2 Time_Period.Hour . to_vector . should_equal [23]
+
+            # Date_Period.Day and Time_Period.Day are interchangeable.
+            ## The results may vary between backends.
+               - In-memory we know this is a DST switch moment and so even if
+                 there's 23 hours between the instants, it is a day difference.
+               - Postgres backend accepts times with timezone, but in its inner
+                 storage, it converts them into UTC. In UTC there is no DST - so
+                 these are 2 instants 23 hours from each other and the database
+                 cannot 'guess' that it should be a day of a difference and
+                 since it is 'just' 23 hours - there is 0 days.
+            [[0], [1]] . should_contain (x.date_diff dt2 Date_Period.Day . to_vector)
+            # Again consistent for both backends, when counting in hours - 23 hours is not a full 24-hour day.
+            x.date_diff dt2 Time_Period.Day . to_vector . should_equal [0]
+
+            dt3 = Date_Time.new 2023 03 28 01 30 00 zone=zone
+            dt4 = Date_Time.new 2023 03 29 00 30 00 zone=zone
+            t2 = table_builder [["X", [dt3]]]
+            # No DST switch here, so all backends agree that 0 days elapsed in the 23 hours.
+            (t2.at "X").date_diff dt4 Date_Period.Day . to_vector . should_equal [0]
+            (t2.at "X").date_diff dt4 Time_Period.Day . to_vector . should_equal [0]
+            (t2.at "X").date_diff dt4 Time_Period.Hour . to_vector . should_equal [23]
+
     if setup.test_selection.date_time.not then
         Test.group prefix+"partial Date-Time support" <|
-            Test.specify "will warn when uploading a Table containing Dates" <|
+            Test.specify "will fail when uploading a Table containing Dates" <|
                 d = Date.new 2020 10 24
                 table = table_builder [["A", [d]], ["X", [123]]]
                 table.should_fail_with Unsupported_Database_Operation
+
+            Test.specify "should report a type error when date operations are invoked on a non-date column" <|
+                t = table_builder [["A", [1, 2, 3]], ["B", ["a", "b", "c"]], ["C", [True, False, True]]]
+                r1 = t.at "A" . year
+                r1.should_fail_with Invalid_Value_Type
+                r1.catch . to_display_text . should_start_with "Expected type Date or Date_Time, but got a column [A] of type Integer"
+                t.at "B" . month . should_fail_with Invalid_Value_Type
+                t.at "C" . day . should_fail_with Invalid_Value_Type
+
+                t.at "A" . date_diff (t.at "B") Date_Period.Day . should_fail_with Invalid_Value_Type
+                t.at "A" . date_add 42 Date_Period.Day . should_fail_with Invalid_Value_Type

test/Table_Tests/src/Common_Table_Operations/Main.enso

@@ -93,7 +93,11 @@ type Test_Selection
          length text columns.
        - supports_decimal_type: Specifies if the backend supports the `Decimal`
          high-precision type.
-    Config supports_case_sensitive_columns=True order_by=True natural_ordering=False case_insensitive_ordering=True order_by_unicode_normalization_by_default=False case_insensitive_ascii_only=False take_drop=True allows_mixed_type_comparisons=True supports_unicode_normalization=False is_nan_and_nothing_distinct=True distinct_returns_first_row_from_group_if_ordered=True date_time=True fixed_length_text_columns=False supports_decimal_type=False
+       - supports_time_duration: Specifies if the backend supports a
+         `Duration`/`Period` type.
+       - supports_nanoseconds_in_time: Specifies if the backend supports
+         nanosecond precision in time values.
+    Config supports_case_sensitive_columns=True order_by=True natural_ordering=False case_insensitive_ordering=True order_by_unicode_normalization_by_default=False case_insensitive_ascii_only=False take_drop=True allows_mixed_type_comparisons=True supports_unicode_normalization=False is_nan_and_nothing_distinct=True distinct_returns_first_row_from_group_if_ordered=True date_time=True fixed_length_text_columns=False supports_decimal_type=False supports_time_duration=False supports_nanoseconds_in_time=False
 
 spec setup =
     Core_Spec.spec setup

test/Table_Tests/src/Common_Table_Operations/Util.enso

@@ -24,3 +24,34 @@ run_default_backend spec =
          within_table t <|
              t.at "A" . to_vector . should_equal [1, 2, 3]
 within_table table = Test.with_clue 'Resulting table:\n'+table.display+'\n\n'
+
+## PRIVATE
+Any.should_equal_tz_agnostic self other =
+    loc = Meta.get_source_location 1
+    _ = other
+    Test.fail "Expected a vector but got "+self.to_display_text+" (at "+loc+")."
+
+## PRIVATE
+   A helper method that compares two vectors of Date_Time values.
+
+   It ensures that they represent the same instant in time, but ignore the
+   timezone that is attached to them. This is simply done by converting them to
+   UTC.
+Vector.should_equal_tz_agnostic self other =
+    loc = Meta.get_source_location 1
+    case other of
+        _ : Vector ->
+            utc = Time_Zone.utc
+            normalize_date_time dt = case dt of
+                _ : Date_Time -> dt.at_zone utc
+                _ -> Test.fail "The vector should contain Date_Time objects but it contained "+dt.to_display_text+" (at "+loc+")"
+            self_normalized = self.map normalize_date_time
+            other_normalized = other.map normalize_date_time
+            self_normalized.should_equal other_normalized frames_to_skip=2
+        _ -> Test.fail "Expected a vector but got "+other.to_display_text+" (at "+loc+")"
+
+## PRIVATE
+Error.should_equal_tz_agnostic self other =
+    loc = Meta.get_source_location 1
+    _ = other
+    Test.fail "Expected a vector but got a dataflow error "+self.catch.to_display_text+" (at "+loc+")."

test/Table_Tests/src/Database/Upload_Spec.enso

@@ -815,19 +815,17 @@ spec make_new_connection prefix persistent_connector=True =
 
             tables_immediately_after = connection.base_connection.get_tables_advanced types=Nothing include_hidden=True . at "Name" . to_vector
 
-            # If no new tables are left out - we just finish.
-            passing_immediately = tables_immediately_after.sort == existing_tables.sort
-            if passing_immediately then Nothing else
-                ## If there are some additional tables, we add some timeout to
-                   allow the database to do the cleaning up.
-                additional_tables = (Set.from_vector tables_immediately_after).difference (Set.from_vector existing_tables)
-                if additional_tables.is_empty then
-                    Test.fail "The Database contains less tables after the test than before! That is unexpected, please inspect manually."
+            ## If there are some additional tables, we add some timeout to allow
+               the database to do the cleaning up.
+            additional_tables = (Set.from_vector tables_immediately_after).difference (Set.from_vector existing_tables)
+            if additional_tables.is_empty then Nothing else
                 additional_table = additional_tables.to_vector.first
 
                 wait_until_temporary_table_is_deleted_after_closing_connection connection additional_table
+                # After the wait we check again and now there should be no additional tables.
                 tables_after_wait = connection.base_connection.get_tables_advanced types=Nothing include_hidden=True . at "Name" . to_vector
-                tables_after_wait . should_contain_the_same_elements_as existing_tables
+                additional_tables_2 = (Set.from_vector tables_after_wait).difference (Set.from_vector existing_tables)
+                additional_tables_2.to_vector . should_equal []
 
     database_table_builder name_prefix args primary_key=[] connection=connection =
         in_memory_table = Table.new args

test/Table_Tests/src/In_Memory/Common_Spec.enso

@@ -7,7 +7,7 @@ from Standard.Test import Test_Suite
 import project.Common_Table_Operations
 
 run_common_spec spec =
-    selection = Common_Table_Operations.Main.Test_Selection.Config supports_case_sensitive_columns=True order_by=True natural_ordering=True case_insensitive_ordering=True order_by_unicode_normalization_by_default=True supports_unicode_normalization=True
+    selection = Common_Table_Operations.Main.Test_Selection.Config supports_case_sensitive_columns=True order_by=True natural_ordering=True case_insensitive_ordering=True order_by_unicode_normalization_by_default=True supports_unicode_normalization=True supports_time_duration=True supports_nanoseconds_in_time=True
     aggregate_selection = Common_Table_Operations.Aggregate_Spec.Test_Selection.Config
 
     table = (enso_project.data / "data.csv") . read

test/Tests/src/Data/Text/Regex_Spec.enso

@@ -3,7 +3,6 @@ import Standard.Base.Data.Text.Span.Span
 import Standard.Base.Data.Text.Span.Utf_16_Span
 import Standard.Base.Data.Text.Regex.Match.Match
 import Standard.Base.Data.Text.Regex.No_Such_Group
-import Standard.Base.Data.Text.Regex.Regex
 import Standard.Base.Data.Text.Regex.Regex_Syntax_Error
 import Standard.Base.Data.Text.Regex.Internal.Replacer.Replacer
 import Standard.Base.Errors.Common.Type_Error

test/Tests/src/Data/Time/Date_Time_Spec.enso

@@ -353,6 +353,10 @@ spec_with name create_new_datetime parse_datetime nanoseconds_loss_in_precision=
             time+Time_Period.Hour . should_equal <| create_new_datetime 1970 1 1 1 (zone = Time_Zone.utc)
             time+Time_Period.Minute . should_equal <| create_new_datetime 1970 1 1 0 1 (zone = Time_Zone.utc)
             time+Time_Period.Second . should_equal <| create_new_datetime 1970 1 1 0 0 1 (zone = Time_Zone.utc)
+            time+Time_Period.Millisecond . should_equal <| create_new_datetime 1970 1 1 0 0 0 (10^6) (zone = Time_Zone.utc)
+            if nanoseconds_loss_in_precision.not then
+                time+Time_Period.Microsecond . should_equal <| create_new_datetime 1970 1 1 0 0 0 (10^3) (zone = Time_Zone.utc)
+                time+Time_Period.Nanosecond . should_equal <| create_new_datetime 1970 1 1 0 0 0 1 (zone = Time_Zone.utc)
 
         Test.specify "should support subtraction of Time_Period" <|
             time = create_new_datetime 1970 (zone = Time_Zone.utc)
@@ -360,6 +364,11 @@ spec_with name create_new_datetime parse_datetime nanoseconds_loss_in_precision=
             time-Time_Period.Hour . should_equal <| create_new_datetime 1969 12 31 23 (zone = Time_Zone.utc)
             time-Time_Period.Minute . should_equal <| create_new_datetime 1969 12 31 23 59 (zone = Time_Zone.utc)
             time-Time_Period.Second . should_equal <| create_new_datetime 1969 12 31 23 59 59 (zone = Time_Zone.utc)
+            second_in_nanos = 10^9
+            time-Time_Period.Millisecond . should_equal <| create_new_datetime 1969 12 31 23 59 59 (second_in_nanos - 10^6) (zone = Time_Zone.utc)
+            if nanoseconds_loss_in_precision.not then
+                time-Time_Period.Microsecond . should_equal <| create_new_datetime 1969 12 31 23 59 59 (second_in_nanos - 10^3) (zone = Time_Zone.utc)
+                time-Time_Period.Nanosecond . should_equal <| create_new_datetime 1969 12 31 23 59 59 (second_in_nanos - 1) (zone = Time_Zone.utc)
 
         Test.specify "should support mixed addition and subtraction of Date_Period and Time_Period" <|
             time = create_new_datetime 1970 (zone = Time_Zone.utc)
@@ -502,6 +511,15 @@ spec_with name create_new_datetime parse_datetime nanoseconds_loss_in_precision=
             d1.end_of Time_Period.Minute . should_equal (Date_Time.new 2022 9 12 15 37 59 nanosecond=max_nanos)
             d1.start_of Time_Period.Second . should_equal (Date_Time.new 2022 9 12 15 37 58 0)
             d1.end_of Time_Period.Second . should_equal (Date_Time.new 2022 9 12 15 37 58 nanosecond=max_nanos)
+            d1.start_of Time_Period.Millisecond . should_equal (Date_Time.new 2022 9 12 15 37 58 nanosecond=123000000)
+            d1.end_of Time_Period.Millisecond . should_equal (Date_Time.new 2022 9 12 15 37 58 nanosecond=123999999)
+
+            if nanoseconds_loss_in_precision.not then
+                d1.start_of Time_Period.Microsecond . should_equal (Date_Time.new 2022 9 12 15 37 58 nanosecond=123456000)
+                d1.end_of Time_Period.Microsecond . should_equal (Date_Time.new 2022 9 12 15 37 58 nanosecond=123456999)
+                # No change on nanosecond
+                d1.start_of Time_Period.Nanosecond . should_equal d1
+                d1.end_of Time_Period.Nanosecond . should_equal d1
 
             d2 = create_new_datetime 1970 1 1 0 0 0
             d2.start_of Time_Period.Day . should_equal (Date_Time.new 1970)
@@ -535,6 +553,8 @@ spec_with name create_new_datetime parse_datetime nanoseconds_loss_in_precision=
             d1_plus . should_equal d2
 
             check_dates_spring date =
+                date.start_of Date_Period.Day . should_equal (Date_Time.new 2022 3 27 zone=tz)
+                date.end_of Date_Period.Day . should_equal (Date_Time.new 2022 3 27 23 59 59 nanosecond=max_nanos zone=tz)
                 date.start_of Time_Period.Day . should_equal (Date_Time.new 2022 3 27 zone=tz)
                 date.end_of Time_Period.Day . should_equal (Date_Time.new 2022 3 27 23 59 59 nanosecond=max_nanos zone=tz)
 

test/Tests/src/Data/Time/Time_Of_Day_Spec.enso

@@ -13,7 +13,7 @@ spec =
     specWith "Time_Of_Day" enso_time Time_Of_Day.parse
     specWith "JavaLocalTime" java_time java_parse
 
-specWith name create_new_time parse_time =
+specWith name create_new_time parse_time nanoseconds_loss_in_precision=False =
     Test.group name <|
 
         Test.specify "should create local time" <|
@@ -123,6 +123,10 @@ specWith name create_new_time parse_time =
             time+Time_Period.Hour . should_equal <| create_new_time 1
             time+Time_Period.Minute . should_equal <| create_new_time 0 1
             time+Time_Period.Second . should_equal <| create_new_time 0 0 1
+            time+Time_Period.Millisecond . should_equal <| create_new_time 0 0 0 10^6
+            if nanoseconds_loss_in_precision.not then
+                time+Time_Period.Microsecond . should_equal <| create_new_time 0 0 0 10^3
+                time+Time_Period.Nanosecond . should_equal <| create_new_time 0 0 0 1
 
         Test.specify "should support subtraction of Time_Period" <|
             time = create_new_time 12
@@ -130,6 +134,11 @@ specWith name create_new_time parse_time =
             time-Time_Period.Hour . should_equal <| create_new_time 11
             time-Time_Period.Minute . should_equal <| create_new_time 11 59
             time-Time_Period.Second . should_equal <| create_new_time 11 59 59
+            second_in_nanos = 10^9
+            time-Time_Period.Millisecond . should_equal <| create_new_time 11 59 59 (second_in_nanos - 10^6)
+            if nanoseconds_loss_in_precision.not then
+                time-Time_Period.Microsecond . should_equal <| create_new_time 11 59 59 (second_in_nanos - 10^3)
+                time-Time_Period.Nanosecond . should_equal <| create_new_time 11 59 59 (second_in_nanos - 1)
 
         Test.specify "should support mixed addition and subtraction of Date_Period and Time_Period" <|
             time = create_new_time 0
@@ -164,6 +173,14 @@ specWith name create_new_time parse_time =
             d1.end_of Time_Period.Minute . should_equal (Time_Of_Day.new 15 37 59 nanosecond=max_nanos)
             d1.start_of Time_Period.Second . should_equal (Time_Of_Day.new 15 37 58 0)
             d1.end_of Time_Period.Second . should_equal (Time_Of_Day.new 15 37 58 nanosecond=max_nanos)
+            d1.start_of Time_Period.Millisecond . should_equal (Time_Of_Day.new 15 37 58 nanosecond=123000000)
+            d1.end_of Time_Period.Millisecond . should_equal (Time_Of_Day.new 15 37 58 nanosecond=123999999)
+
+            if nanoseconds_loss_in_precision.not then
+                d1.start_of Time_Period.Microsecond . should_equal (Time_Of_Day.new 15 37 58 nanosecond=123456000)
+                d1.end_of Time_Period.Microsecond . should_equal (Time_Of_Day.new 15 37 58 nanosecond=123456999)
+                d1.start_of Time_Period.Nanosecond . should_equal d1
+                d1.end_of Time_Period.Nanosecond . should_equal d1
 
             d2 = create_new_time 0 0 0
             d2.start_of Time_Period.Day . should_equal (Time_Of_Day.new)