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dd37456949
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5787 GitOrigin-RevId: f5f01a64ccffa36c93a0a88228ac927fbd3aa168
60 lines
2.7 KiB
Haskell
60 lines
2.7 KiB
Haskell
-- | This module defines the top-level translation functions pertaining to
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-- queries that use aggregation (i.e., /not/ so-called "simple" selects) into
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-- Postgres AST.
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module Hasura.Backends.Postgres.Translate.Select.Aggregate
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( mkAggregateSelect,
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selectAggregateQuerySQL,
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)
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where
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import Control.Monad.Writer.Strict (runWriter)
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import Database.PG.Query (Query, fromBuilder)
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import Hasura.Backends.Postgres.SQL.DML (BoolExp (BELit), Select)
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import Hasura.Backends.Postgres.SQL.RenameIdentifiers (renameIdentifiers)
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import Hasura.Backends.Postgres.SQL.Types (IsIdentifier (toIdentifier))
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import Hasura.Backends.Postgres.Translate.Select.AnnotatedFieldJSON
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import Hasura.Backends.Postgres.Translate.Select.Internal.GenerateSelect (generateSQLSelectFromArrayNode)
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import Hasura.Backends.Postgres.Translate.Select.Internal.Process (processAnnAggregateSelect)
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import Hasura.Backends.Postgres.Translate.Types (MultiRowSelectNode (MultiRowSelectNode), SelectNode (SelectNode), SourcePrefixes (SourcePrefixes))
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import Hasura.Prelude
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import Hasura.RQL.IR.Select (AnnAggregateSelect, AnnSelectG (_asnStrfyNum))
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import Hasura.RQL.Types.Backend (Backend)
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import Hasura.RQL.Types.Common (FieldName (FieldName))
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import Hasura.SQL.Backend (BackendType (Postgres))
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import Hasura.SQL.Types (ToSQL (toSQL))
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-- | Translates IR to Postgres queries for aggregated SELECTs.
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--
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-- See 'mkAggregateSelect' for the Postgres AST.
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selectAggregateQuerySQL ::
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forall pgKind.
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(Backend ('Postgres pgKind), PostgresAnnotatedFieldJSON pgKind) =>
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AnnAggregateSelect ('Postgres pgKind) ->
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Query
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selectAggregateQuerySQL = fromBuilder . toSQL . mkAggregateSelect
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-- | We process aggregate queries differently because the types of aggregate queries are different.
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-- In the '_asnFields' field of an 'AnnSelectG', we will have a 'TableAggregateFieldG' instead
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-- of an 'AnnFieldG'.
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mkAggregateSelect ::
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forall pgKind.
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(Backend ('Postgres pgKind), PostgresAnnotatedFieldJSON pgKind) =>
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AnnAggregateSelect ('Postgres pgKind) ->
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Select
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mkAggregateSelect annAggSel =
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let ((selectSource, nodeExtractors, topExtractor), joinTree) =
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runWriter $
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flip runReaderT strfyNum $
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processAnnAggregateSelect sourcePrefixes rootFieldName annAggSel
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-- select the relevant columns and subquery we want to aggregate
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selectNode = SelectNode nodeExtractors joinTree
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-- aggregate the results into a top-level return value
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arrayNode = MultiRowSelectNode [topExtractor] selectNode
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in renameIdentifiers $
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generateSQLSelectFromArrayNode selectSource arrayNode $ BELit True
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where
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strfyNum = _asnStrfyNum annAggSel
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rootFieldName = FieldName "root"
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rootIdentifier = toIdentifier rootFieldName
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sourcePrefixes = SourcePrefixes rootIdentifier rootIdentifier
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