mirror of
https://github.com/hasura/graphql-engine.git
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b6799f0882
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/8946 GitOrigin-RevId: 434e7c335bc69119020dd35761c7d4539bc51ff8
338 lines
13 KiB
Haskell
338 lines
13 KiB
Haskell
{-# LANGUAGE TemplateHaskell #-}
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-- | Postgres Execute subscription
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--
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-- Multiplex is an optimization which allows us to group similar queries into a
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-- single query, and routing the response rows afterwards. See
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-- https://hasura.io/docs/latest/graphql/core/databases/postgres/subscriptions/execution-and-performance.html
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-- for more details
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--
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-- See 'Hasura.Backends.Postgres.Instances.Execute'.
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module Hasura.Backends.Postgres.Execute.Subscription
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( MultiplexedQuery (..),
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QueryParametersInfo (..),
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mkMultiplexedQuery,
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mkStreamingMultiplexedQuery,
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resolveMultiplexedValue,
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validateVariablesTx,
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executeMultiplexedQuery,
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executeStreamingMultiplexedQuery,
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executeQuery,
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SubscriptionType (..),
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)
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where
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import Control.Lens
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import Control.Monad.Writer
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import Data.ByteString qualified as B
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import Data.HashMap.Strict qualified as HashMap
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import Data.HashMap.Strict.InsOrd qualified as InsOrdHashMap
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import Data.HashSet qualified as Set
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import Data.Semigroup.Generic
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import Data.Text.Extended
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import Database.PG.Query qualified as PG
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import Hasura.Backends.Postgres.Connection
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import Hasura.Backends.Postgres.SQL.DML qualified as S
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import Hasura.Backends.Postgres.SQL.Error
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import Hasura.Backends.Postgres.SQL.Types
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import Hasura.Backends.Postgres.SQL.Value
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import Hasura.Backends.Postgres.Translate.Column (toTxtValue)
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import Hasura.Backends.Postgres.Translate.Select qualified as DS
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import Hasura.Backends.Postgres.Translate.Select.Internal.Helpers (customSQLToInnerCTEs, toQuery)
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import Hasura.Backends.Postgres.Translate.Types (CustomSQLCTEs (..))
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import Hasura.Backends.Postgres.Types.Column
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import Hasura.Base.Error
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import Hasura.GraphQL.Execute.Subscription.Plan
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import Hasura.GraphQL.Parser.Names
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import Hasura.Prelude
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import Hasura.RQL.IR
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import Hasura.RQL.Types.Backend
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import Hasura.RQL.Types.BackendType
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import Hasura.RQL.Types.Column
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import Hasura.RQL.Types.Common
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import Hasura.RQL.Types.Subscription
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import Hasura.SQL.Types
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import Hasura.Session
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import Language.GraphQL.Draft.Syntax qualified as G
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----------------------------------------------------------------------------------------------------
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-- Variables
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subsAlias :: S.TableAlias
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subsAlias = S.mkTableAlias "_subs"
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subsIdentifier :: TableIdentifier
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subsIdentifier = S.tableAliasToIdentifier subsAlias
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resultIdAlias, resultVarsAlias :: S.ColumnAlias
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resultIdAlias = S.mkColumnAlias "result_id"
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resultVarsAlias = S.mkColumnAlias "result_vars"
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fldRespAlias :: S.TableAlias
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fldRespAlias = S.mkTableAlias "_fld_resp"
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fldRespIdentifier :: TableIdentifier
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fldRespIdentifier = S.tableAliasToIdentifier fldRespAlias
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-- | Internal: Used to collect information about various parameters
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-- of a subscription field's AST as we resolve them to SQL expressions.
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data QueryParametersInfo (b :: BackendType) = QueryParametersInfo
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{ _qpiReusableVariableValues :: HashMap G.Name (ColumnValue b),
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_qpiSyntheticVariableValues :: Seq (ColumnValue b),
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-- | The session variables that are referenced in the query root fld's AST.
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-- This information is used to determine a cohort's required session
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-- variables
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_qpiReferencedSessionVariables :: Set.HashSet SessionVariable
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}
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deriving (Generic)
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deriving (Semigroup, Monoid) via (GenericSemigroupMonoid (QueryParametersInfo b))
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makeLenses ''QueryParametersInfo
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-- | Checks if the provided arguments are valid values for their corresponding types.
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-- | Generates SQL of the format "select 'v1'::t1, 'v2'::t2 ..."
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validateVariablesTx ::
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forall pgKind f m.
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(Traversable f, MonadTx m, MonadIO m) =>
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f (ColumnValue ('Postgres pgKind)) ->
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m (ValidatedVariables f)
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validateVariablesTx variableValues = do
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-- no need to test the types when there are no variables to test.
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unless (null variableValues) do
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let valSel = mkValidationSel $ toList variableValues
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PG.Discard () <- liftTx $ PG.rawQE dataExnErrHandler (PG.fromBuilder $ toSQL valSel) [] False
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pure ()
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pure . ValidatedVariables $ fmap (txtEncodedVal . cvValue) variableValues
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where
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mkExtr = flip S.Extractor Nothing . toTxtValue
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mkValidationSel vars =
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S.mkSelect {S.selExtr = map mkExtr vars}
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-- Explicitly look for the class of errors raised when the format of a value
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-- provided for a type is incorrect.
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dataExnErrHandler = mkTxErrorHandler (has _PGDataException)
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----------------------------------------------------------------------------------------------------
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-- Multiplexed queries
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newtype MultiplexedQuery = MultiplexedQuery {unMultiplexedQuery :: PG.Query}
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deriving (Eq, Hashable)
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instance ToTxt MultiplexedQuery where
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toTxt = PG.getQueryText . unMultiplexedQuery
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toSQLFromItem ::
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( Backend ('Postgres pgKind),
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DS.PostgresAnnotatedFieldJSON pgKind,
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MonadWriter CustomSQLCTEs m
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) =>
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S.TableAlias ->
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QueryDB ('Postgres pgKind) Void S.SQLExp ->
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m S.FromItem
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toSQLFromItem tableAlias = \case
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QDBSingleRow s -> S.mkSelFromItem <$> DS.mkSQLSelect JASSingleObject s <*> pure tableAlias
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QDBMultipleRows s -> S.mkSelFromItem <$> DS.mkSQLSelect JASMultipleRows s <*> pure tableAlias
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QDBAggregation s -> S.mkSelFromItem <$> DS.mkAggregateSelect s <*> pure tableAlias
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QDBConnection s -> S.mkSelectWithFromItem <$> DS.mkConnectionSelect s <*> pure tableAlias
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QDBStreamMultipleRows s -> S.mkSelFromItem <$> DS.mkStreamSQLSelect s <*> pure tableAlias
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mkMultiplexedQuery ::
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( Backend ('Postgres pgKind),
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DS.PostgresAnnotatedFieldJSON pgKind
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) =>
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InsOrdHashMap.InsOrdHashMap G.Name (QueryDB ('Postgres pgKind) Void S.SQLExp) ->
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MultiplexedQuery
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mkMultiplexedQuery rootFields =
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MultiplexedQuery . toQuery $ selectWith
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where
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select =
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S.mkSelect
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{ S.selExtr =
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-- SELECT _subs.result_id, _fld_resp.root AS result
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[ S.Extractor (mkQualifiedIdentifier subsIdentifier (Identifier "result_id")) Nothing,
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S.Extractor (mkQualifiedIdentifier fldRespIdentifier (Identifier "root")) (Just $ S.toColumnAlias $ Identifier "result")
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],
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S.selFrom =
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Just $
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S.FromExp
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[ S.FIJoin $
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S.JoinExpr subsInputFromItem S.LeftOuter responseLateralFromItem (S.JoinOn $ S.BELit True)
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]
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}
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-- multiplexed queries may only contain read only raw queries
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selectWith = S.SelectWith [] select
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-- FROM unnest($1::uuid[], $2::json[]) _subs (result_id, result_vars)
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subsInputFromItem =
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S.FIUnnest
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[S.SEPrep 1 `S.SETyAnn` S.TypeAnn "uuid[]", S.SEPrep 2 `S.SETyAnn` S.TypeAnn "json[]"]
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subsAlias
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[S.toColumnAlias $ Identifier "result_id", S.toColumnAlias $ Identifier "result_vars"]
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(sqlFrom, customSQLCTEs) =
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runWriter $
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traverse
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( \(fieldAlias, resolvedAST) ->
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toSQLFromItem (S.mkTableAlias $ G.unName fieldAlias) resolvedAST
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)
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(InsOrdHashMap.toList rootFields)
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-- LEFT OUTER JOIN LATERAL ( ... ) _fld_resp
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responseLateralFromItem = S.mkLateralFromItem selectRootFields fldRespAlias
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selectRootFields =
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S.mkSelect
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{ S.selExtr = [S.Extractor rootFieldsJsonAggregate (Just $ S.toColumnAlias $ Identifier "root")],
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S.selCTEs = customSQLToInnerCTEs customSQLCTEs,
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S.selFrom =
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Just $ S.FromExp sqlFrom
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}
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-- json_build_object('field1', field1.root, 'field2', field2.root, ...)
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rootFieldsJsonAggregate = S.SEFnApp "json_build_object" rootFieldsJsonPairs Nothing
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rootFieldsJsonPairs = flip concatMap (InsOrdHashMap.keys rootFields) $ \fieldAlias ->
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[ S.SELit (G.unName fieldAlias),
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mkQualifiedIdentifier (aliasToIdentifier fieldAlias) (Identifier "root")
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]
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mkQualifiedIdentifier prefix = S.SEQIdentifier . S.QIdentifier (S.QualifiedIdentifier prefix Nothing)
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aliasToIdentifier = TableIdentifier . G.unName
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mkStreamingMultiplexedQuery ::
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( Backend ('Postgres pgKind),
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DS.PostgresAnnotatedFieldJSON pgKind
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) =>
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(G.Name, (QueryDB ('Postgres pgKind) Void S.SQLExp)) ->
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MultiplexedQuery
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mkStreamingMultiplexedQuery (fieldAlias, resolvedAST) =
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MultiplexedQuery . toQuery $ selectWith
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where
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selectWith = S.SelectWith [] select
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select =
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S.mkSelect
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{ S.selExtr =
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-- SELECT _subs.result_id, _fld_resp.root, _fld_resp.cursor AS result
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[ S.Extractor (mkQualifiedIdentifier subsIdentifier (Identifier "result_id")) Nothing,
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S.Extractor (mkQualifiedIdentifier fldRespIdentifier (Identifier "root")) (Just $ S.toColumnAlias $ Identifier "result"),
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S.Extractor (mkQualifiedIdentifier fldRespIdentifier (Identifier "cursor")) (Just $ S.toColumnAlias $ Identifier "cursor")
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],
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S.selFrom =
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Just $
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S.FromExp
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[ S.FIJoin $
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S.JoinExpr subsInputFromItem S.LeftOuter responseLateralFromItem (S.JoinOn $ S.BELit True)
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]
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}
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-- FROM unnest($1::uuid[], $2::json[]) _subs (result_id, result_vars)
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subsInputFromItem =
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S.FIUnnest
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[S.SEPrep 1 `S.SETyAnn` S.TypeAnn "uuid[]", S.SEPrep 2 `S.SETyAnn` S.TypeAnn "json[]"]
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subsAlias
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[resultIdAlias, resultVarsAlias]
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-- LEFT OUTER JOIN LATERAL ( ... ) _fld_resp
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responseLateralFromItem = S.mkLateralFromItem selectRootFields fldRespAlias
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(fromSQL, customSQLCTEs) = runWriter (toSQLFromItem (S.mkTableAlias $ G.unName fieldAlias) resolvedAST)
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selectRootFields =
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S.mkSelect
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{ S.selExtr = [(S.Extractor rootFieldJsonAggregate (Just $ S.toColumnAlias $ Identifier "root")), cursorExtractor],
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S.selCTEs = customSQLToInnerCTEs customSQLCTEs,
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S.selFrom =
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Just $ S.FromExp [fromSQL]
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}
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-- json_build_object('field1', field1.root, 'field2', field2.root, ...)
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rootFieldJsonAggregate = S.SEFnApp "json_build_object" rootFieldJsonPair Nothing
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rootFieldJsonPair =
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[ S.SELit (G.unName fieldAlias),
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mkQualifiedIdentifier (aliasToIdentifier fieldAlias) (Identifier "root")
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]
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-- to_json("root"."cursor") AS "cursor"
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cursorSQLExp = S.SEFnApp "to_json" [mkQualifiedIdentifier (aliasToIdentifier fieldAlias) (Identifier "cursor")] Nothing
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cursorExtractor = S.Extractor cursorSQLExp (Just $ S.toColumnAlias $ Identifier "cursor")
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mkQualifiedIdentifier prefix = S.SEQIdentifier . S.QIdentifier (S.QualifiedIdentifier prefix Nothing)
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aliasToIdentifier = TableIdentifier . G.unName
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-- | Resolves an 'GR.UnresolvedVal' by converting 'GR.UVPG' values to SQL
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-- expressions that refer to the @result_vars@ input object, collecting information
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-- about various parameters of the query along the way.
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resolveMultiplexedValue ::
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( MonadState (QueryParametersInfo ('Postgres pgKind)) m,
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MonadError QErr m
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) =>
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SessionVariables ->
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UnpreparedValue ('Postgres pgKind) ->
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m S.SQLExp
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resolveMultiplexedValue allSessionVars = \case
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UVParameter provenance colVal -> do
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varJsonPath <- case provenance of
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FromGraphQL varInfo -> do
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let varName = getName varInfo
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modifying qpiReusableVariableValues $ HashMap.insert varName colVal
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pure ["query", G.unName varName]
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_ -> do
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syntheticVarIndex <- use (qpiSyntheticVariableValues . to length)
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modifying qpiSyntheticVariableValues (|> colVal)
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pure ["synthetic", tshow syntheticVarIndex]
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pure $ fromResVars (CollectableTypeScalar $ unsafePGColumnToBackend $ cvType colVal) varJsonPath
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UVSessionVar ty sessVar -> do
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_ <-
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getSessionVariableValue sessVar allSessionVars
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`onNothing` throw400
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NotFound
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("missing session variable: " <>> sessionVariableToText sessVar)
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modifying qpiReferencedSessionVariables (Set.insert sessVar)
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pure $ fromResVars ty ["session", sessionVariableToText sessVar]
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UVLiteral sqlExp -> pure sqlExp
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UVSession -> do
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-- if the entire session is referenced, then add all session vars in referenced vars
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modifying qpiReferencedSessionVariables (const $ getSessionVariablesSet allSessionVars)
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pure $ fromResVars (CollectableTypeScalar PGJSON) ["session"]
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where
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fromResVars pgType jPath =
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addTypeAnnotation pgType $
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S.SEOpApp
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(S.SQLOp "#>>")
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[ S.SEQIdentifier $ S.QIdentifier (S.QualifiedIdentifier subsIdentifier Nothing) (Identifier "result_vars"),
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S.SEArray $ map S.SELit jPath
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]
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addTypeAnnotation pgType =
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flip S.SETyAnn (S.mkTypeAnn pgType) . case pgType of
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CollectableTypeScalar scalarType -> withConstructorFn scalarType
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CollectableTypeArray _ -> id
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----------------------------------------------------------------------------------------------------
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-- Execution
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executeMultiplexedQuery ::
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(MonadTx m) =>
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MultiplexedQuery ->
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[(CohortId, CohortVariables)] ->
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m [(CohortId, B.ByteString)]
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executeMultiplexedQuery (MultiplexedQuery query) cohorts =
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executeQuery query cohorts
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executeStreamingMultiplexedQuery ::
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(MonadTx m) =>
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MultiplexedQuery ->
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[(CohortId, CohortVariables)] ->
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m [(CohortId, B.ByteString, PG.ViaJSON CursorVariableValues)]
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executeStreamingMultiplexedQuery (MultiplexedQuery query) cohorts = do
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executeQuery query cohorts
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-- | Internal; used by both 'executeMultiplexedQuery', 'executeStreamingMultiplexedQuery'
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-- and 'pgDBSubscriptionExplain'.
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executeQuery ::
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(MonadTx m, PG.FromRes a) =>
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PG.Query ->
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[(CohortId, CohortVariables)] ->
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m a
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executeQuery query cohorts =
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let (cohortIds, cohortVars) = unzip cohorts
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preparedArgs = (CohortIdArray cohortIds, CohortVariablesArray cohortVars)
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in liftTx $ PG.withQE defaultTxErrorHandler query preparedArgs True
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