-- | Translate from the DML to the BigQuery dialect. module Hasura.Backends.BigQuery.FromIr ( fromSelectRows , mkSQLSelect , fromRootField , fromSelectAggregate , Error(..) , runFromIr , FromIr ) where import Hasura.Prelude import qualified Data.HashMap.Strict as HM import qualified Data.List.NonEmpty as NE import qualified Data.Map.Strict as M import qualified Data.Text as T import Control.Monad.Validate import Data.Map.Strict (Map) import Data.Proxy import qualified Hasura.RQL.IR as Ir import qualified Hasura.RQL.Types.Column as Rql import qualified Hasura.RQL.Types.Common as Rql import qualified Hasura.RQL.Types.Relationship as Rql import Hasura.Backends.BigQuery.Instances.Types () import Hasura.Backends.BigQuery.Types as BigQuery import Hasura.SQL.Backend -------------------------------------------------------------------------------- -- Types -- | Most of these errors should be checked for legitimacy. data Error = FromTypeUnsupported (Ir.SelectFromG 'BigQuery Expression) | NoOrderSpecifiedInOrderBy | MalformedAgg | FieldTypeUnsupportedForNow (Ir.AnnFieldG 'BigQuery Expression) | AggTypeUnsupportedForNow (Ir.TableAggregateFieldG 'BigQuery Expression) | NodesUnsupportedForNow (Ir.TableAggregateFieldG 'BigQuery Expression) | NoProjectionFields | NoAggregatesMustBeABug | UnsupportedArraySelect (Ir.ArraySelectG 'BigQuery Expression) | UnsupportedOpExpG (Ir.OpExpG 'BigQuery Expression) | UnsupportedSQLExp Expression | UnsupportedDistinctOn | InvalidIntegerishSql Expression | DistinctIsn'tSupported | ConnectionsNotSupported | ActionsNotSupported instance Show Error where show = \case FromTypeUnsupported {} -> "FromTypeUnsupported" NoOrderSpecifiedInOrderBy {} -> "NoOrderSpecifiedInOrderBy" MalformedAgg {} -> "MalformedAgg" FieldTypeUnsupportedForNow {} -> "FieldTypeUnsupportedForNow" AggTypeUnsupportedForNow {} -> "AggTypeUnsupportedForNow" NodesUnsupportedForNow {} -> "NodesUnsupportedForNow" NoProjectionFields {} -> "NoProjectionFields" NoAggregatesMustBeABug {} -> "NoAggregatesMustBeABug" UnsupportedArraySelect {} -> "UnsupportedArraySelect" UnsupportedOpExpG {} -> "UnsupportedOpExpG" UnsupportedSQLExp {} -> "UnsupportedSQLExp" UnsupportedDistinctOn {} -> "UnsupportedDistinctOn" InvalidIntegerishSql {} -> "InvalidIntegerishSql" DistinctIsn'tSupported {} -> "DistinctIsn'tSupported" ConnectionsNotSupported {} -> "ConnectionsNotSupported" ActionsNotSupported {} -> "ActionsNotSupported" -- | The base monad used throughout this module for all conversion -- functions. -- -- It's a Validate, so it'll continue going when it encounters errors -- to accumulate as many as possible. -- -- It also contains a mapping from entity prefixes to counters. So if -- my prefix is "table" then there'll be a counter that lets me -- generate table1, table2, etc. Same for any other prefix needed -- (e.g. names for joins). -- -- A ReaderT is used around this in most of the module too, for -- setting the current entity that a given field name refers to. See -- @fromPGCol@. newtype FromIr a = FromIr { unFromIr :: StateT (Map Text Int) (Validate (NonEmpty Error)) a } deriving (Functor, Applicative, Monad, MonadValidate (NonEmpty Error)) data StringifyNumbers = StringifyNumbers | LeaveNumbersAlone deriving (Eq) -------------------------------------------------------------------------------- -- Runners runFromIr :: FromIr a -> Validate (NonEmpty Error) a runFromIr fromIr = evalStateT (unFromIr fromIr) mempty -------------------------------------------------------------------------------- -- Similar rendition of old API -- | Here is where we apply a top-level annotation to the select to -- indicate to the data loader that this select ought to produce a -- single object or an array. mkSQLSelect :: Rql.JsonAggSelect -> Ir.AnnSelectG 'BigQuery (Ir.AnnFieldsG 'BigQuery Expression) Expression -> FromIr BigQuery.Select mkSQLSelect jsonAggSelect annSimpleSel = do select <- fromSelectRows annSimpleSel pure (select { selectCardinality = case jsonAggSelect of Rql.JASMultipleRows -> Many Rql.JASSingleObject -> One }) -- | Convert from the IR database query into a select. fromRootField :: Ir.QueryDB 'BigQuery Expression -> FromIr Select fromRootField = \case (Ir.QDBSingleRow s) -> mkSQLSelect Rql.JASSingleObject s (Ir.QDBMultipleRows s) -> mkSQLSelect Rql.JASMultipleRows s (Ir.QDBAggregation s) -> fromSelectAggregate s (Ir.QDBConnection _) -> refute $ pure ConnectionsNotSupported -------------------------------------------------------------------------------- -- Top-level exported functions fromSelectRows :: Ir.AnnSelectG 'BigQuery (Ir.AnnFieldsG 'BigQuery Expression) Expression -> FromIr BigQuery.Select fromSelectRows annSelectG = do selectFrom <- case from of Ir.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject _ -> refute (pure (FromTypeUnsupported from)) Args { argsOrderBy , argsWhere , argsJoins , argsTop , argsDistinct = Proxy , argsOffset , argsExistingJoins } <- runReaderT (fromSelectArgsG args) (fromAlias selectFrom) fieldSources <- runReaderT (traverse (fromAnnFieldsG argsExistingJoins stringifyNumbers) fields) (fromAlias selectFrom) filterExpression <- runReaderT (fromAnnBoolExp permFilter) (fromAlias selectFrom) selectProjections <- case NE.nonEmpty (concatMap (toList . fieldSourceProjections) fieldSources) of Nothing -> refute (pure NoProjectionFields) Just ne -> pure ne pure Select {selectCardinality = Many, selectFinalWantedFields = pure (fieldTextNames fields), selectGroupBy = mempty , selectOrderBy = argsOrderBy , selectTop = permissionBasedTop <> argsTop , selectProjections , selectFrom , selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources , selectWhere = argsWhere <> Where [filterExpression] , selectOffset = argsOffset } where Ir.AnnSelectG { _asnFields = fields , _asnFrom = from , _asnPerm = perm , _asnArgs = args , _asnStrfyNum = num } = annSelectG Ir.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm permissionBasedTop = maybe NoTop Top mPermLimit stringifyNumbers = if num then StringifyNumbers else LeaveNumbersAlone fromSelectAggregate :: Ir.AnnSelectG 'BigQuery [(Rql.FieldName, Ir.TableAggregateFieldG 'BigQuery Expression)] Expression -> FromIr BigQuery.Select fromSelectAggregate annSelectG = do selectFrom <- case from of Ir.FromTable qualifiedObject -> fromQualifiedTable qualifiedObject _ -> refute (pure (FromTypeUnsupported from)) args'@Args {argsWhere, argsOrderBy, argsJoins, argsTop, argsOffset, argsDistinct = Proxy} <- runReaderT (fromSelectArgsG args) (fromAlias selectFrom) filterExpression <- runReaderT (fromAnnBoolExp permFilter) (fromAlias selectFrom) fieldSources <- runReaderT (traverse (fromTableAggregateFieldG args' permissionBasedTop stringifyNumbers) fields) (fromAlias selectFrom) selectProjections <- case NE.nonEmpty (concatMap (toList . fieldSourceProjections) fieldSources) of Nothing -> refute (pure NoProjectionFields) Just ne -> pure ne pure Select { selectCardinality = One , selectFinalWantedFields = Nothing , selectGroupBy = mempty , selectProjections , selectTop = NoTop , selectFrom = FromSelect (Aliased { aliasedThing = Select { selectProjections = pure StarProjection , selectFrom , selectJoins = argsJoins <> mapMaybe fieldSourceJoin fieldSources , selectWhere = argsWhere <> (Where [filterExpression]) , selectOrderBy = argsOrderBy -- Above: This is important to have here, because -- offset/top apply AFTER ordering is applied, so -- you can't put an order by in afterwards in a -- parent query. Therefore be careful about -- putting this elsewhere. , selectFinalWantedFields = Nothing , selectCardinality = Many , selectTop = argsTop , selectOffset = argsOffset , selectGroupBy = mempty } , aliasedAlias = entityAliasText (fromAlias selectFrom) }) , selectJoins = mempty , selectWhere = mempty , selectOrderBy = Nothing , selectOffset = Nothing } where Ir.AnnSelectG { _asnFields = fields , _asnFrom = from , _asnPerm = perm , _asnArgs = args , _asnStrfyNum = num -- TODO: Do we ignore this for aggregates? } = annSelectG Ir.TablePerm {_tpLimit = mPermLimit, _tpFilter = permFilter} = perm permissionBasedTop = case mPermLimit of Nothing -> NoTop Just limit -> Top limit stringifyNumbers = if num then StringifyNumbers else LeaveNumbersAlone -------------------------------------------------------------------------------- -- GraphQL Args data Args = Args { argsWhere :: Where , argsOrderBy :: Maybe (NonEmpty OrderBy) , argsJoins :: [Join] , argsTop :: Top , argsOffset :: Maybe Expression , argsDistinct :: Proxy (Maybe (NonEmpty FieldName)) , argsExistingJoins :: Map TableName EntityAlias } deriving (Show) data UnfurledJoin = UnfurledJoin { unfurledJoin :: Join , unfurledObjectTableAlias :: Maybe (TableName, EntityAlias) -- ^ Recorded if we joined onto an object relation. } deriving (Show) fromSelectArgsG :: Ir.SelectArgsG 'BigQuery Expression -> ReaderT EntityAlias FromIr Args fromSelectArgsG selectArgsG = do let argsOffset = ValueExpression . IntegerValue . Int64 . tshow <$> moffset argsWhere <- maybe (pure mempty) (fmap (Where . pure) . fromAnnBoolExp) mannBoolExp argsTop <- maybe (pure mempty) (pure . Top) mlimit -- Not supported presently, per Vamshi: -- -- > It is hardly used and we don't have to go to great lengths to support it. -- -- But placeholdering the code so that when it's ready to be used, -- you can just drop the Proxy wrapper. argsDistinct <- case mdistinct of Nothing -> pure Proxy Just {} -> refute (pure DistinctIsn'tSupported) (argsOrderBy, joins) <- runWriterT (traverse fromAnnOrderByItemG (maybe [] toList orders)) -- Any object-relation joins that we generated, we record their -- generated names into a mapping. let argsExistingJoins = M.fromList (mapMaybe unfurledObjectTableAlias (toList joins)) pure Args { argsJoins = toList (fmap unfurledJoin joins) , argsOrderBy = NE.nonEmpty argsOrderBy , .. } where Ir.SelectArgs { _saWhere = mannBoolExp , _saLimit = mlimit , _saOffset = moffset , _saDistinct = mdistinct , _saOrderBy = orders } = selectArgsG -- | Produce a valid ORDER BY construct, telling about any joins -- needed on the side. fromAnnOrderByItemG :: Ir.AnnOrderByItemG 'BigQuery Expression -> WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) OrderBy fromAnnOrderByItemG Ir.OrderByItemG {obiType, obiColumn, obiNulls} = do orderByFieldName <- unfurlAnnOrderByElement obiColumn let morderByOrder = obiType let orderByNullsOrder = fromMaybe NullsAnyOrder obiNulls case morderByOrder of Just orderByOrder -> pure OrderBy {..} Nothing -> refute (pure NoOrderSpecifiedInOrderBy) -- | Unfurl the nested set of object relations (tell'd in the writer) -- that are terminated by field name (Ir.AOCColumn and -- Ir.AOCArrayAggregation). unfurlAnnOrderByElement :: Ir.AnnOrderByElement 'BigQuery Expression -> WriterT (Seq UnfurledJoin) (ReaderT EntityAlias FromIr) FieldName unfurlAnnOrderByElement = \case Ir.AOCColumn pgColumnInfo -> lift (fromPGColumnInfo pgColumnInfo) Ir.AOCObjectRelation Rql.RelInfo {riMapping = mapping, riRTable = tableName} annBoolExp annOrderByElementG -> do selectFrom <- lift (lift (fromQualifiedTable tableName)) joinAliasEntity <- lift (lift (generateEntityAlias (ForOrderAlias (tableNameText tableName)))) joinOn <- lift (fromMappingFieldNames joinAliasEntity mapping) whereExpression <- lift (local (const (fromAlias selectFrom)) (fromAnnBoolExp annBoolExp)) tell (pure UnfurledJoin { unfurledJoin = Join { joinSource = JoinSelect Select {selectCardinality = One, selectFinalWantedFields = Nothing, selectGroupBy = mempty , selectTop = NoTop , selectProjections = NE.fromList [StarProjection] , selectFrom , selectJoins = [] , selectWhere = Where ([whereExpression]) , selectOrderBy = Nothing , selectOffset = Nothing } , joinRightTable = fromAlias selectFrom , joinAlias = joinAliasEntity , joinOn , joinProvenance = OrderByJoinProvenance , joinFieldName = tableNameText tableName -- TODO: not needed. , joinExtractPath = Nothing } , unfurledObjectTableAlias = Just (tableName, joinAliasEntity) }) local (const joinAliasEntity) (unfurlAnnOrderByElement annOrderByElementG) Ir.AOCArrayAggregation Rql.RelInfo {riMapping = mapping, riRTable = tableName} annBoolExp annAggregateOrderBy -> do selectFrom <- lift (lift (fromQualifiedTable tableName)) let alias = aggFieldName joinAlias <- lift (lift (generateEntityAlias (ForOrderAlias (tableNameText tableName)))) joinOn <- lift (fromMappingFieldNames joinAlias mapping) innerJoinFields <- lift (fromMappingFieldNames (fromAlias selectFrom) mapping) whereExpression <- lift (local (const (fromAlias selectFrom)) (fromAnnBoolExp annBoolExp)) aggregate <- lift (local (const (fromAlias selectFrom)) (case annAggregateOrderBy of Ir.AAOCount -> pure (CountAggregate StarCountable) Ir.AAOOp text pgColumnInfo -> do fieldName <- fromPGColumnInfo pgColumnInfo pure (OpAggregate text (ColumnExpression fieldName)))) tell (pure (UnfurledJoin { unfurledJoin = Join { joinSource = JoinSelect Select {selectCardinality = One, selectFinalWantedFields = Nothing, selectTop = NoTop , selectProjections = AggregateProjection Aliased { aliasedThing = aggregate , aliasedAlias = alias } :| -- These are group by'd below in selectGroupBy. map (\(fieldName', _) -> FieldNameProjection Aliased { aliasedThing = fieldName' , aliasedAlias = fieldName fieldName' }) innerJoinFields , selectFrom , selectJoins = [] , selectWhere = Where [whereExpression] , selectOrderBy = Nothing , selectOffset = Nothing -- This group by corresponds to the field name projections above. , selectGroupBy = map fst innerJoinFields } , joinRightTable = fromAlias selectFrom , joinProvenance = OrderByJoinProvenance , joinAlias = joinAlias , joinOn , joinFieldName = tableNameText tableName -- TODO: not needed. , joinExtractPath = Nothing } , unfurledObjectTableAlias = Nothing })) pure FieldName {fieldNameEntity = entityAliasText joinAlias, fieldName = alias} -------------------------------------------------------------------------------- -- Conversion functions tableNameText :: TableName -> Text tableNameText (TableName {tableName=qname}) = qname -- | This is really the start where you query the base table, -- everything else is joins attached to it. fromQualifiedTable :: TableName -> FromIr From fromQualifiedTable (TableName {tableNameSchema=schemaName,tableName=qname}) = do alias <- generateEntityAlias (TableTemplate qname) pure (FromQualifiedTable (Aliased { aliasedThing = TableName {tableName = qname, tableNameSchema = schemaName} , aliasedAlias = entityAliasText alias })) fromAnnBoolExp :: Ir.GBoolExp 'BigQuery (Ir.AnnBoolExpFld 'BigQuery Expression) -> ReaderT EntityAlias FromIr Expression fromAnnBoolExp = traverse fromAnnBoolExpFld >=> fromGBoolExp fromAnnBoolExpFld :: Ir.AnnBoolExpFld 'BigQuery Expression -> ReaderT EntityAlias FromIr Expression fromAnnBoolExpFld = \case Ir.AVCol pgColumnInfo opExpGs -> do expression <- fmap ColumnExpression (fromPGColumnInfo pgColumnInfo) expressions <- traverse (lift . fromOpExpG expression) opExpGs pure (AndExpression expressions) Ir.AVRel Rql.RelInfo {riMapping = mapping, riRTable = table} annBoolExp -> do selectFrom <- lift (fromQualifiedTable table) foreignKeyConditions <- fromMapping selectFrom mapping whereExpression <- local (const (fromAlias selectFrom)) (fromAnnBoolExp annBoolExp) pure (ExistsExpression Select {selectCardinality = One, selectFinalWantedFields = Nothing, selectGroupBy = mempty , selectOrderBy = Nothing , selectProjections = NE.fromList [ ExpressionProjection (Aliased { aliasedThing = trueExpression , aliasedAlias = existsFieldName }) ] , selectFrom , selectJoins = mempty , selectWhere = Where (foreignKeyConditions <> [whereExpression]) , selectTop = NoTop , selectOffset = Nothing }) fromPGColumnInfo :: Rql.ColumnInfo 'BigQuery -> ReaderT EntityAlias FromIr FieldName fromPGColumnInfo Rql.ColumnInfo {pgiColumn = ColumnName pgCol} = do EntityAlias {entityAliasText} <- ask pure (FieldName {fieldName = pgCol, fieldNameEntity = entityAliasText}) fromGExists :: Ir.GExists 'BigQuery Expression -> ReaderT EntityAlias FromIr Select fromGExists Ir.GExists {_geTable, _geWhere} = do selectFrom <- lift (fromQualifiedTable _geTable) whereExpression <- local (const (fromAlias selectFrom)) (fromGBoolExp _geWhere) pure Select {selectCardinality = One, selectFinalWantedFields = Nothing, selectGroupBy = mempty , selectOrderBy = Nothing , selectProjections = NE.fromList [ ExpressionProjection (Aliased { aliasedThing = trueExpression , aliasedAlias = existsFieldName }) ] , selectFrom , selectJoins = mempty , selectWhere = Where [whereExpression] , selectTop = NoTop , selectOffset = Nothing } -------------------------------------------------------------------------------- -- Sources of projected fields -- -- Because in the IR, a field projected can be a foreign object, we -- have to both generate a projection AND on the side generate a join. -- -- So a @FieldSource@ couples the idea of the projected thing and the -- source of it (via 'Aliased'). data FieldSource = ExpressionFieldSource (Aliased Expression) | JoinFieldSource (Aliased Join) | AggregateFieldSource Text (NonEmpty (Aliased Aggregate)) | ArrayAggFieldSource (Aliased ArrayAgg) deriving (Eq, Show) -- Example: -- -- @ -- Track_aggregate { -- aggregate { -- count(columns: AlbumId) -- foo: count(columns: AlbumId) -- max { -- AlbumId -- TrackId -- } -- } -- } -- @ -- -- field = -- @ -- TAFAgg -- [ ( FieldName {getFieldNameTxt = "count"} -- , AFCount (CTSimple [PGCol {getPGColTxt = "AlbumId"}])) -- , ( FieldName {getFieldNameTxt = "foo"} -- , AFCount (CTSimple [PGCol {getPGColTxt = "AlbumId"}])) -- , ( FieldName {getFieldNameTxt = "max"} -- , AFOp -- (AggregateOp -- { _aoOp = "max" -- , _aoFields = -- [ ( FieldName {getFieldNameTxt = "AlbumId"} -- , CFCol (PGCol {getPGColTxt = "AlbumId"})) -- , ( FieldName {getFieldNameTxt = "TrackId"} -- , CFCol (PGCol {getPGColTxt = "TrackId"})) -- ] -- })) -- ] -- @ -- -- should produce: -- -- SELECT COUNT(`t_Track1`.`AlbumId`) AS `count`, -- COUNT(`t_Track1`.`AlbumId`) AS `foo`, -- struct(max(`t_Track1`.`AlbumId`) AS `AlbumId`, max(`t_Track1`.`TrackId`) as TrackId) as `max` -- FROM chinook.`Track` AS `t_Track1` -- fromTableAggregateFieldG :: Args -> Top -> StringifyNumbers -> (Rql.FieldName, Ir.TableAggregateFieldG 'BigQuery Expression) -> ReaderT EntityAlias FromIr FieldSource fromTableAggregateFieldG args permissionBasedTop stringifyNumbers (Rql.FieldName name, field) = case field of Ir.TAFAgg (aggregateFields :: [(Rql.FieldName, Ir.AggregateField 'BigQuery)]) -> case NE.nonEmpty aggregateFields of Nothing -> refute (pure NoAggregatesMustBeABug) Just fields -> do aggregates <- traverse (\(fieldName, aggregateField) -> do fmap (\aliasedThing -> Aliased {aliasedAlias = Rql.getFieldNameTxt fieldName, ..}) (fromAggregateField aggregateField)) fields pure (AggregateFieldSource name aggregates) Ir.TAFExp text -> pure (ExpressionFieldSource Aliased { aliasedThing = BigQuery.ValueExpression (StringValue text) , aliasedAlias = name }) Ir.TAFNodes _ (fields :: [(Rql.FieldName, Ir.AnnFieldG 'BigQuery Expression)]) -> do fieldSources <- traverse (fromAnnFieldsG (argsExistingJoins args) stringifyNumbers) fields arrayAggProjections <- case NE.nonEmpty (concatMap (toList . fieldSourceProjections) fieldSources) of Nothing -> refute (pure NoProjectionFields) Just ne -> pure ne pure (ArrayAggFieldSource Aliased { aliasedThing = ArrayAgg { arrayAggProjections , arrayAggOrderBy = argsOrderBy args , arrayAggTop = argsTop args <> permissionBasedTop } , aliasedAlias = name }) fromAggregateField :: Ir.AggregateField 'BigQuery -> ReaderT EntityAlias FromIr Aggregate fromAggregateField aggregateField = case aggregateField of Ir.AFExp text -> pure (TextAggregate text) Ir.AFCount countType -> CountAggregate <$> case countType of StarCountable -> pure StarCountable NonNullFieldCountable names -> NonNullFieldCountable <$> traverse fromPGCol names DistinctCountable names -> DistinctCountable <$> traverse fromPGCol names Ir.AFOp Ir.AggregateOp {_aoOp = op, _aoFields = fields} -> do fs <- NE.nonEmpty fields `onNothing` refute (pure MalformedAgg) args <- traverse (\(Rql.FieldName fieldName, pgColFld) -> do expression' <- case pgColFld of Ir.CFCol pgCol _columnType -> fmap ColumnExpression (fromPGCol pgCol) Ir.CFExp text -> pure (ValueExpression (StringValue text)) pure (fieldName, expression')) fs pure (OpAggregates op args) -- | The main sources of fields, either constants, fields or via joins. fromAnnFieldsG :: Map TableName EntityAlias -> StringifyNumbers -> (Rql.FieldName, Ir.AnnFieldG 'BigQuery Expression) -> ReaderT EntityAlias FromIr FieldSource fromAnnFieldsG existingJoins stringifyNumbers (Rql.FieldName name, field) = case field of Ir.AFColumn annColumnField -> do expression <- fromAnnColumnField stringifyNumbers annColumnField pure (ExpressionFieldSource Aliased {aliasedThing = expression, aliasedAlias = name}) Ir.AFExpression text -> pure (ExpressionFieldSource Aliased { aliasedThing = BigQuery.ValueExpression (StringValue text) , aliasedAlias = name }) Ir.AFObjectRelation objectRelationSelectG -> fmap (\aliasedThing -> JoinFieldSource (Aliased {aliasedThing, aliasedAlias = name})) (fromObjectRelationSelectG existingJoins objectRelationSelectG) Ir.AFArrayRelation arraySelectG -> fmap (\aliasedThing -> JoinFieldSource (Aliased {aliasedThing, aliasedAlias = name})) (fromArraySelectG arraySelectG) -- this will be gone once the code which collects remote joins from the IR -- emits a modified IR where remote relationships can't be reached Ir.AFRemote _ -> pure (ExpressionFieldSource Aliased { aliasedThing = BigQuery.ValueExpression (StringValue "null: remote field selected") , aliasedAlias = name }) -- | Here is where we project a field as a column expression. If -- number stringification is on, then we wrap it in a -- 'ToStringExpression' so that it's casted when being projected. fromAnnColumnField :: StringifyNumbers -> Ir.AnnColumnField 'BigQuery Expression -> ReaderT EntityAlias FromIr Expression fromAnnColumnField _stringifyNumbers annColumnField = do fieldName <- fromPGCol pgCol if asText || False -- TOOD: (Rql.isScalarColumnWhere Psql.isBigNum typ && stringifyNumbers == StringifyNumbers) then pure (ToStringExpression (ColumnExpression fieldName)) else case caseBoolExpMaybe of Nothing -> pure (ColumnExpression fieldName) Just ex -> do ex' <- (traverse fromAnnBoolExpFld >=> fromGBoolExp) (coerce ex) pure (ConditionalProjection ex' fieldName) where Ir.AnnColumnField { _acfInfo = Rql.ColumnInfo{pgiColumn=pgCol,pgiType=_typ} , _acfAsText = asText :: Bool , _acfOp = _ :: Maybe (Ir.ColumnOp 'BigQuery) -- TODO: What's this? , _acfCaseBoolExpression = caseBoolExpMaybe :: Maybe (Ir.AnnColumnCaseBoolExp 'BigQuery Expression) } = annColumnField -- | This is where a field name "foo" is resolved to a fully qualified -- field name [table].[foo]. The table name comes from EntityAlias in -- the ReaderT. fromPGCol :: ColumnName -> ReaderT EntityAlias FromIr FieldName fromPGCol (ColumnName txt) = do EntityAlias {entityAliasText} <- ask pure (FieldName {fieldName = txt, fieldNameEntity = entityAliasText}) fieldSourceProjections :: FieldSource -> NonEmpty Projection fieldSourceProjections = \case ExpressionFieldSource aliasedExpression -> pure (ExpressionProjection aliasedExpression) JoinFieldSource aliasedJoin -> NE.fromList -- Here we're producing all join fields needed later for -- Haskell-native joining. They will be removed by upstream -- code. ([ FieldNameProjection (Aliased {aliasedThing = right, aliasedAlias = fieldNameText right}) | (_left, right) <- joinOn join' ] <> -- Below: -- When we're doing an array-aggregate, e.g. -- -- query MyQuery { -- hasura_Artist { -- albums_aggregate { -- aggregate { -- count -- } -- } -- } -- } -- -- we're going to do a join on the albums table, and that -- join query will produce a single-row result. Therefore we -- can grab the whole entity as a STRUCT-typed object. See -- also the docs for 'fromArrayRelationSelectG' and for -- 'fromArrayAggregateSelectG'. case joinProvenance join' of ArrayJoinProvenance fields -> pure (ArrayEntityProjection (joinAlias join') aliasedJoin { aliasedThing = fmap (\name -> FieldName { fieldName = name , fieldNameEntity = entityAliasText (joinAlias join') }) fields , aliasedAlias = aliasedAlias aliasedJoin }) ObjectJoinProvenance fields -> pure (EntityProjection aliasedJoin { aliasedThing = fmap (\name -> ( FieldName { fieldName = name , fieldNameEntity = entityAliasText (joinAlias join') } , NoOrigin)) fields , aliasedAlias = aliasedAlias aliasedJoin }) ArrayAggregateJoinProvenance fields -> pure (EntityProjection aliasedJoin { aliasedThing = fmap (\(name, fieldOrigin) -> ( FieldName { fieldName = name , fieldNameEntity = entityAliasText (joinAlias join') } , fieldOrigin)) fields , aliasedAlias = aliasedAlias aliasedJoin }) _ -> []) where join' = aliasedThing aliasedJoin AggregateFieldSource name aggregates -> pure (AggregateProjections (Aliased {aliasedThing = aggregates, aliasedAlias = name})) ArrayAggFieldSource arrayAgg -> pure (ArrayAggProjection arrayAgg) where fieldNameText FieldName {fieldName} = fieldName fieldSourceJoin :: FieldSource -> Maybe Join fieldSourceJoin = \case JoinFieldSource aliasedJoin -> pure (aliasedThing aliasedJoin) ExpressionFieldSource {} -> Nothing AggregateFieldSource {} -> Nothing ArrayAggFieldSource {} -> Nothing -------------------------------------------------------------------------------- -- Joins -- | Produce the join for an object relation. We produce a normal -- select, but then include join fields. Then downstream, the -- DataLoader will execute the lhs select and rhs join in separate -- server queries, then do a Haskell-native join on the join fields. -- -- See also 'fromArrayRelationSelectG' for similar example. fromObjectRelationSelectG :: Map TableName EntityAlias -> Ir.ObjectRelationSelectG 'BigQuery Expression -> ReaderT EntityAlias FromIr Join -- We're not using existingJoins at the moment, which was used to -- avoid re-joining on the same table twice. fromObjectRelationSelectG _existingJoins annRelationSelectG = do selectFrom <- lift (fromQualifiedTable tableFrom) let entityAlias :: EntityAlias = fromAlias selectFrom fieldSources <- local (const entityAlias) (traverse (fromAnnFieldsG mempty LeaveNumbersAlone) fields) selectProjections <- NE.nonEmpty (concatMap (toList . fieldSourceProjections) fieldSources) `onNothing` refute (pure NoProjectionFields) joinFieldName <- lift (fromRelName aarRelationshipName) joinAlias <- lift (generateEntityAlias (ObjectRelationTemplate joinFieldName)) filterExpression <- local (const entityAlias) (fromAnnBoolExp tableFilter) innerJoinFields <- fromMappingFieldNames (fromAlias selectFrom) mapping joinOn <- fromMappingFieldNames joinAlias mapping let joinFieldProjections = map (\(fieldName', _) -> FieldNameProjection Aliased { aliasedThing = fieldName' , aliasedAlias = fieldName fieldName' }) innerJoinFields let selectFinalWantedFields = pure (fieldTextNames fields) pure Join { joinAlias , joinSource = JoinSelect Select { selectCardinality = One , selectFinalWantedFields , selectGroupBy = mempty , selectOrderBy = Nothing , selectTop = NoTop , selectProjections = NE.fromList joinFieldProjections <> selectProjections , selectFrom , selectJoins = mapMaybe fieldSourceJoin fieldSources , selectWhere = Where [filterExpression] , selectOffset = Nothing } , joinOn , joinRightTable = fromAlias selectFrom , joinProvenance = ObjectJoinProvenance (fromMaybe [] selectFinalWantedFields) -- TODO: OK? -- Above: Needed by DataLoader to determine the type of -- Haskell-native join to perform. , joinFieldName , joinExtractPath = Nothing } where Ir.AnnObjectSelectG { _aosFields = fields :: Ir.AnnFieldsG 'BigQuery Expression , _aosTableFrom = tableFrom :: TableName , _aosTableFilter = tableFilter :: Ir.AnnBoolExp 'BigQuery Expression } = annObjectSelectG Ir.AnnRelationSelectG { aarRelationshipName , aarColumnMapping = mapping :: HashMap ColumnName ColumnName , aarAnnSelect = annObjectSelectG :: Ir.AnnObjectSelectG 'BigQuery Expression } = annRelationSelectG -- We're not using existingJoins at the moment, which was used to -- avoid re-joining on the same table twice. _lookupTableFrom :: Map TableName EntityAlias -> TableName -> FromIr (Either EntityAlias From) _lookupTableFrom existingJoins tableFrom = do case M.lookup tableFrom existingJoins of Just entityAlias -> pure (Left entityAlias) Nothing -> fmap Right (fromQualifiedTable tableFrom) fromArraySelectG :: Ir.ArraySelectG 'BigQuery Expression -> ReaderT EntityAlias FromIr Join fromArraySelectG = \case Ir.ASSimple arrayRelationSelectG -> fromArrayRelationSelectG arrayRelationSelectG Ir.ASAggregate arrayAggregateSelectG -> fromArrayAggregateSelectG arrayAggregateSelectG -- | Produce the join for an array aggregate relation. We produce a -- normal select, but then include join fields. Then downstream, the -- DataLoader will execute the lhs select and rhs join in separate -- server queries, then do a Haskell-native join on the join fields. -- -- See also 'fromArrayRelationSelectG' for similar example. fromArrayAggregateSelectG :: Ir.AnnRelationSelectG 'BigQuery (Ir.AnnAggregateSelectG 'BigQuery Expression) -> ReaderT EntityAlias FromIr Join fromArrayAggregateSelectG annRelationSelectG = do joinFieldName <- lift (fromRelName aarRelationshipName) select <- lift (fromSelectAggregate annSelectG) alias <- lift (generateEntityAlias (ArrayAggregateTemplate joinFieldName)) joinOn <- fromMappingFieldNames alias mapping innerJoinFields <- fromMappingFieldNames (fromAlias (selectFrom select)) mapping let joinFieldProjections = map (\(fieldName', _) -> FieldNameProjection Aliased { aliasedThing = fieldName' , aliasedAlias = fieldName fieldName' }) innerJoinFields let projections = (selectProjections select <> NE.fromList joinFieldProjections) let joinSelect = select { selectWhere = selectWhere select , selectGroupBy = map fst innerJoinFields , selectProjections = projections } pure Join { joinAlias = alias , joinSource = JoinSelect joinSelect , joinRightTable = fromAlias (selectFrom select) , joinOn , joinProvenance = ArrayAggregateJoinProvenance $ mapMaybe (\p -> (, aggregateProjectionsFieldOrigin p) <$> projectionAlias p) . toList . selectProjections $ select -- Above: Needed by DataLoader to determine the type of -- Haskell-native join to perform. , joinFieldName , joinExtractPath = Nothing } where Ir.AnnRelationSelectG { aarRelationshipName , aarColumnMapping = mapping :: HashMap ColumnName ColumnName , aarAnnSelect = annSelectG } = annRelationSelectG -- | Produce a join for an array relation. -- -- Array relations in PG/MSSQL are expressed using LEFT OUTER JOIN -- LATERAL or OUTER APPLY, which are essentially producing for each -- row on the left an array of the result from the right. Which is -- absolutely what you want for the array relationship. -- -- BigQuery doesn't support that. Therefore we are instead performing -- one big array aggregation, for ALL rows in the table - there is no -- join occurring on the left-hand-side table, grouped by join -- fields. The data-loader will perform the LHS query and the RHS query -- separately. -- -- What we do have is a GROUP BY and make sure that the join fields -- are included in the output. Finally, in the -- DataLoader.Plan/DataLoader.Execute, we implement a Haskell-native -- join of the left-hand-side table and the right-hand-side table. -- -- Data looks like: -- -- join_field_a | join_field_b | aggFieldName (array type) -- 1 | 1 | [ { x: 1, y: 2 }, ... ] -- 1 | 2 | [ { x: 1, y: 2 }, ... ] -- -- etc. -- -- We want to produce a query that looks like: -- -- SELECT artist_other_id, -- For joining. -- -- array_agg(struct(album_self_id, title)) as aggFieldName -- -- -- ^ Aggregating the actual data. -- -- FROM (SELECT *, -- Get everything, plus the row number: -- -- ROW_NUMBER() OVER(PARTITION BY artist_other_id) artist_album_index -- -- FROM hasura.Album -- ORDER BY album_self_id ASC -- -- -- ^ Order by here is important for stable results. Any -- order by clauses for the album should appear here, NOT IN -- THE ARRAY_AGG. -- -- ) -- -- AS indexed_album -- -- WHERE artist_album_index > 1 -- -- ^ Here is where offsetting occurs. -- -- GROUP BY artist_other_id -- -- ^ Group by for joining. -- -- ORDER BY artist_other_id; -- ^ Ordering for the artist table should appear here. fromArrayRelationSelectG :: Ir.ArrayRelationSelectG 'BigQuery Expression -> ReaderT EntityAlias FromIr Join fromArrayRelationSelectG annRelationSelectG = do select <- lift (fromSelectRows annSelectG) -- Take the original select. joinFieldName <- lift (fromRelName aarRelationshipName) alias <- lift (generateEntityAlias (ArrayRelationTemplate joinFieldName)) indexAlias <- lift (generateEntityAlias IndexTemplate) joinOn <- fromMappingFieldNames alias mapping innerJoinFields <- fromMappingFieldNames (fromAlias (selectFrom select)) mapping let joinFieldProjections = map (\(fieldName', _) -> FieldNameProjection Aliased { aliasedThing = fieldName' , aliasedAlias = fieldName fieldName' }) innerJoinFields joinSelect <- pure Select { selectCardinality = One , selectFinalWantedFields = selectFinalWantedFields select , selectTop = NoTop , selectProjections = NE.fromList joinFieldProjections <> pure (ArrayAggProjection Aliased { aliasedThing = ArrayAgg { arrayAggProjections = fmap aliasToFieldProjection (selectProjections select) , arrayAggOrderBy = Nothing , arrayAggTop = selectTop select -- This handles the LIMIT need. } , aliasedAlias = aggFieldName }) , selectFrom = FromSelect (Aliased { aliasedAlias = coerce (fromAlias (selectFrom select)) , aliasedThing = Select { selectProjections = selectProjections select <> NE.fromList joinFieldProjections <> pure (WindowProjection (Aliased { aliasedAlias = unEntityAlias indexAlias , aliasedThing = RowNumberOverPartitionBy -- The row numbers start from 1. (NE.fromList (map (\(fieldName', _) -> fieldName') innerJoinFields)) (selectOrderBy select) -- Above: Having the order by -- in here ensures that the -- row numbers are ordered by -- this ordering. Below, we -- order again for the -- general row order. Both -- are needed! })) , selectFrom = selectFrom select , selectJoins = selectJoins select , selectWhere = selectWhere select , selectOrderBy = selectOrderBy select -- Above: This orders the rows themselves. In -- the RowNumberOverPartitionBy, we also set -- a row order for the calculation of the -- indices. Both are needed! , selectOffset = Nothing , selectFinalWantedFields = selectFinalWantedFields select , selectCardinality = Many , selectTop = NoTop , selectGroupBy = mempty } }) , selectWhere = case selectOffset select of Nothing -> mempty Just offset -> Where [ OpExpression MoreOp (ColumnExpression FieldName {fieldNameEntity = coerce (fromAlias (selectFrom select)), fieldName = unEntityAlias indexAlias}) offset ] , selectOrderBy = Nothing -- Not needed. , selectJoins = mempty , selectOffset = Nothing -- This group by corresponds to the field name projections above. E.g. artist_other_id , selectGroupBy = map (\(fieldName', _) -> fieldName') innerJoinFields } pure Join { joinAlias = alias , joinSource = JoinSelect joinSelect , joinRightTable = fromAlias (selectFrom select) , joinOn , joinProvenance = ArrayJoinProvenance (if True then (fromMaybe [] (selectFinalWantedFields select)) else (mapMaybe projectionAlias (toList (selectProjections select)))) -- Above: Needed by DataLoader to determine the type of -- Haskell-native join to perform. , joinFieldName , joinExtractPath = Just aggFieldName } where Ir.AnnRelationSelectG { aarRelationshipName , aarColumnMapping = mapping :: HashMap ColumnName ColumnName , aarAnnSelect = annSelectG } = annRelationSelectG -- | For entity projections, convert any entity aliases to their field -- names. TODO: Add an explanation for this. aliasToFieldProjection :: Projection -> Projection aliasToFieldProjection = \case EntityProjection Aliased {aliasedAlias = name, aliasedThing = fields} -> EntityProjection Aliased { aliasedAlias = name , aliasedThing = fmap (\(FieldName {..}, origin) -> (FieldName {fieldNameEntity = name, ..}, origin)) fields } p -> p fromRelName :: Rql.RelName -> FromIr Text fromRelName relName = pure (Rql.relNameToTxt relName) -- | The context given by the reader is of the previous/parent -- "remote" table. The WHERE that we're generating goes in the child, -- "local" query. The @From@ passed in as argument is the local table. -- -- We should hope to see e.g. "post.category = category.id" for a -- local table of post and a remote table of category. -- -- The left/right columns in @HashMap ColumnName ColumnName@ corresponds -- to the left/right of @select ... join ...@. Therefore left=remote, -- right=local in this context. fromMapping :: From -> HashMap ColumnName ColumnName -> ReaderT EntityAlias FromIr [Expression] fromMapping localFrom = traverse (\(remotePgCol, localPgCol) -> do localFieldName <- local (const (fromAlias localFrom)) (fromPGCol localPgCol) remoteFieldName <- fromPGCol remotePgCol pure (EqualExpression (ColumnExpression localFieldName) (ColumnExpression remoteFieldName))) . HM.toList fromMappingFieldNames :: EntityAlias -> HashMap ColumnName ColumnName -> ReaderT EntityAlias FromIr [(FieldName,FieldName)] fromMappingFieldNames localFrom = traverse (\(remotePgCol, localPgCol) -> do localFieldName <- local (const localFrom) (fromPGCol localPgCol) remoteFieldName <- fromPGCol remotePgCol pure ((,) (localFieldName) (remoteFieldName))) . HM.toList -------------------------------------------------------------------------------- -- Basic SQL expression types fromOpExpG :: Expression -> Ir.OpExpG 'BigQuery Expression -> FromIr Expression fromOpExpG expression op = case op of Ir.ANISNULL -> pure (IsNullExpression expression) Ir.ANISNOTNULL -> pure (IsNotNullExpression expression) Ir.AEQ False val -> pure (nullableBoolEquality expression val) Ir.AEQ True val -> pure (EqualExpression expression val) Ir.ANE False val -> pure (nullableBoolInequality expression val) Ir.ANE True val -> pure (NotEqualExpression expression val) Ir.AGT val -> pure (OpExpression MoreOp expression val) Ir.ALT val -> pure (OpExpression LessOp expression val) Ir.AGTE val -> pure (OpExpression MoreOrEqualOp expression val) Ir.ALTE val -> pure (OpExpression LessOrEqualOp expression val) Ir.ACast _casts -> refute (pure (UnsupportedOpExpG op)) -- mkCastsExp casts Ir.AIN _val -> refute (pure (UnsupportedOpExpG op)) -- S.BECompareAny S.SEQ lhs val Ir.ANIN _val -> refute (pure (UnsupportedOpExpG op)) -- S.BENot $ S.BECompareAny S.SEQ lhs val Ir.ALIKE _val -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SLIKE lhs val Ir.ANLIKE _val -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SNLIKE lhs val Ir.CEQ _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SEQ lhs $ mkQCol rhsCol Ir.CNE _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SNE lhs $ mkQCol rhsCol Ir.CGT _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SGT lhs $ mkQCol rhsCol Ir.CLT _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SLT lhs $ mkQCol rhsCol Ir.CGTE _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SGTE lhs $ mkQCol rhsCol Ir.CLTE _rhsCol -> refute (pure (UnsupportedOpExpG op)) -- S.BECompare S.SLTE lhs $ mkQCol rhsCol -- These are new as of 2021-02-18 to this API. Not sure what to do with them at present, marking as unsupported. nullableBoolEquality :: Expression -> Expression -> Expression nullableBoolEquality x y = OrExpression [ EqualExpression x y , AndExpression [IsNullExpression x, IsNullExpression y] ] nullableBoolInequality :: Expression -> Expression -> Expression nullableBoolInequality x y = OrExpression [ NotEqualExpression x y , AndExpression [IsNotNullExpression x, IsNullExpression y] ] fromGBoolExp :: Ir.GBoolExp 'BigQuery Expression -> ReaderT EntityAlias FromIr Expression fromGBoolExp = \case Ir.BoolAnd expressions -> fmap AndExpression (traverse fromGBoolExp expressions) Ir.BoolOr expressions -> fmap OrExpression (traverse fromGBoolExp expressions) Ir.BoolNot expression -> fmap NotExpression (fromGBoolExp expression) Ir.BoolExists gExists -> fmap ExistsExpression (fromGExists gExists) Ir.BoolFld expression -> pure expression -------------------------------------------------------------------------------- -- Misc combinators trueExpression :: Expression trueExpression = ValueExpression (BoolValue True) -------------------------------------------------------------------------------- -- Constants aggFieldName :: Text aggFieldName = "agg" existsFieldName :: Text existsFieldName = "exists_placeholder" -------------------------------------------------------------------------------- -- Name generation data NameTemplate = ArrayRelationTemplate Text | ArrayAggregateTemplate Text | ObjectRelationTemplate Text | TableTemplate Text | ForOrderAlias Text | IndexTemplate generateEntityAlias :: NameTemplate -> FromIr EntityAlias generateEntityAlias template = do FromIr (modify' (M.insertWith (+) prefix start)) i <- FromIr get pure (EntityAlias (prefix <> tshow (fromMaybe start (M.lookup prefix i)))) where start = 1 prefix = T.take 20 rendered rendered = case template of ArrayRelationTemplate sample -> "ar_" <> sample ArrayAggregateTemplate sample -> "aa_" <> sample ObjectRelationTemplate sample -> "or_" <> sample TableTemplate sample -> "t_" <> sample ForOrderAlias sample -> "order_" <> sample IndexTemplate -> "idx" fromAlias :: From -> EntityAlias fromAlias (FromQualifiedTable Aliased {aliasedAlias}) = EntityAlias aliasedAlias fromAlias (FromSelect Aliased {aliasedAlias}) = EntityAlias aliasedAlias fieldTextNames :: Ir.AnnFieldsG 'BigQuery Expression -> [Text] fieldTextNames = fmap (\(Rql.FieldName name, _) -> name) unEntityAlias :: EntityAlias -> Text unEntityAlias (EntityAlias t) = t