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server/src-lib/Hasura/Backends/Postgres/Execute/LiveQuery.hs
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| module Hasura.Backends.Postgres.Execute.LiveQuery | ||
| ( MultiplexedQuery (..) | ||
| , QueryParametersInfo (..) | ||
| , mkMultiplexedQuery | ||
| , resolveMultiplexedValue | ||
| , validateVariables | ||
| , executeMultiplexedQuery | ||
| , executeQuery | ||
| ) where | ||
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| import Hasura.Prelude | ||
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| import qualified Data.ByteString as B | ||
| import qualified Data.HashMap.Strict as Map | ||
| import qualified Data.HashMap.Strict.InsOrd as OMap | ||
| import qualified Data.HashSet as Set | ||
| import qualified Database.PG.Query as Q | ||
| import qualified Language.GraphQL.Draft.Syntax as G | ||
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| import Control.Lens | ||
| import Data.Semigroup.Generic | ||
| import Data.Text.Extended | ||
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| import qualified Hasura.Backends.Postgres.SQL.DML as S | ||
| import qualified Hasura.Backends.Postgres.Translate.Select as DS | ||
| import qualified Hasura.GraphQL.Parser.Schema as PS | ||
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| import Hasura.Backends.Postgres.Connection | ||
| import Hasura.Backends.Postgres.SQL.Error | ||
| import Hasura.Backends.Postgres.SQL.Types | ||
| import Hasura.Backends.Postgres.SQL.Value | ||
| import Hasura.Backends.Postgres.Translate.Column (toTxtValue) | ||
| import Hasura.GraphQL.Context | ||
| import Hasura.GraphQL.Execute.LiveQuery.Plan | ||
| import Hasura.GraphQL.Parser | ||
| import Hasura.RQL.Types | ||
| import Hasura.SQL.Types | ||
| import Hasura.Session | ||
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| ---------------------------------------------------------------------------------------------------- | ||
| -- Variables | ||
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| -- | Internal: Used to collect information about various parameters | ||
| -- of a subscription field's AST as we resolve them to SQL expressions. | ||
| data QueryParametersInfo | ||
| = QueryParametersInfo | ||
| { _qpiReusableVariableValues :: !(HashMap G.Name (ColumnValue 'Postgres)) | ||
| , _qpiSyntheticVariableValues :: !(Seq (ColumnValue 'Postgres)) | ||
| , _qpiReferencedSessionVariables :: !(Set.HashSet SessionVariable) | ||
| -- ^ The session variables that are referenced in the query root fld's AST. | ||
| -- This information is used to determine a cohort's required session | ||
| -- variables | ||
| } deriving (Generic) | ||
| deriving (Semigroup, Monoid) via (GenericSemigroupMonoid QueryParametersInfo) | ||
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| makeLenses ''QueryParametersInfo | ||
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| -- | Checks if the provided arguments are valid values for their corresponding types. | ||
| -- | Generates SQL of the format "select 'v1'::t1, 'v2'::t2 ..." | ||
| validateVariables | ||
| :: (Traversable f, MonadError QErr m, MonadIO m) | ||
| => PGExecCtx | ||
| -> f (ColumnValue 'Postgres) | ||
| -> m (ValidatedVariables f) | ||
| validateVariables pgExecCtx variableValues = do | ||
| let valSel = mkValidationSel $ toList variableValues | ||
| Q.Discard () <- runQueryTx_ $ liftTx $ | ||
| Q.rawQE dataExnErrHandler (Q.fromBuilder $ toSQL valSel) [] False | ||
| pure . ValidatedVariables $ fmap (txtEncodedPGVal . cvValue) variableValues | ||
| where | ||
| mkExtr = flip S.Extractor Nothing . toTxtValue | ||
| mkValidationSel vars = | ||
| S.mkSelect { S.selExtr = map mkExtr vars } | ||
| runQueryTx_ tx = do | ||
| res <- liftIO $ runExceptT (runQueryTx pgExecCtx tx) | ||
| liftEither res | ||
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| -- Explicitly look for the class of errors raised when the format of a value | ||
| -- provided for a type is incorrect. | ||
| dataExnErrHandler = mkTxErrorHandler (has _PGDataException) | ||
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| ---------------------------------------------------------------------------------------------------- | ||
| -- Multiplexed queries | ||
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| newtype MultiplexedQuery = MultiplexedQuery { unMultiplexedQuery :: Q.Query } | ||
| deriving (Eq, Hashable) | ||
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| instance ToTxt MultiplexedQuery where | ||
| toTxt = Q.getQueryText . unMultiplexedQuery | ||
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| toSQLFromItem :: S.Alias -> QueryDB 'Postgres S.SQLExp -> S.FromItem | ||
| toSQLFromItem = flip \case | ||
| QDBSingleRow s -> S.mkSelFromItem $ DS.mkSQLSelect JASSingleObject s | ||
| QDBMultipleRows s -> S.mkSelFromItem $ DS.mkSQLSelect JASMultipleRows s | ||
| QDBAggregation s -> S.mkSelFromItem $ DS.mkAggregateSelect s | ||
| QDBConnection s -> S.mkSelectWithFromItem $ DS.mkConnectionSelect s | ||
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| mkMultiplexedQuery :: OMap.InsOrdHashMap G.Name (QueryDB 'Postgres S.SQLExp) -> MultiplexedQuery | ||
| mkMultiplexedQuery rootFields = MultiplexedQuery . Q.fromBuilder . toSQL $ S.mkSelect | ||
| { S.selExtr = | ||
| -- SELECT _subs.result_id, _fld_resp.root AS result | ||
| [ S.Extractor (mkQualifiedIdentifier (Identifier "_subs") (Identifier "result_id")) Nothing | ||
| , S.Extractor (mkQualifiedIdentifier (Identifier "_fld_resp") (Identifier "root")) (Just . S.Alias $ Identifier "result") ] | ||
| , S.selFrom = Just $ S.FromExp [S.FIJoin $ | ||
| S.JoinExpr subsInputFromItem S.LeftOuter responseLateralFromItem (S.JoinOn $ S.BELit True)] | ||
| } | ||
| where | ||
| -- FROM unnest($1::uuid[], $2::json[]) _subs (result_id, result_vars) | ||
| subsInputFromItem = S.FIUnnest | ||
| [S.SEPrep 1 `S.SETyAnn` S.TypeAnn "uuid[]", S.SEPrep 2 `S.SETyAnn` S.TypeAnn "json[]"] | ||
| (S.Alias $ Identifier "_subs") | ||
| [S.SEIdentifier $ Identifier "result_id", S.SEIdentifier $ Identifier "result_vars"] | ||
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| -- LEFT OUTER JOIN LATERAL ( ... ) _fld_resp | ||
| responseLateralFromItem = S.mkLateralFromItem selectRootFields (S.Alias $ Identifier "_fld_resp") | ||
| selectRootFields = S.mkSelect | ||
| { S.selExtr = [S.Extractor rootFieldsJsonAggregate (Just . S.Alias $ Identifier "root")] | ||
| , S.selFrom = Just . S.FromExp $ | ||
| OMap.toList rootFields <&> \(fieldAlias, resolvedAST) -> | ||
| toSQLFromItem (S.Alias $ aliasToIdentifier fieldAlias) resolvedAST | ||
| } | ||
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| -- json_build_object('field1', field1.root, 'field2', field2.root, ...) | ||
| rootFieldsJsonAggregate = S.SEFnApp "json_build_object" rootFieldsJsonPairs Nothing | ||
| rootFieldsJsonPairs = flip concatMap (OMap.keys rootFields) $ \fieldAlias -> | ||
| [ S.SELit (G.unName fieldAlias) | ||
| , mkQualifiedIdentifier (aliasToIdentifier fieldAlias) (Identifier "root") ] | ||
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| mkQualifiedIdentifier prefix = S.SEQIdentifier . S.QIdentifier (S.QualifiedIdentifier prefix Nothing) -- TODO fix this Nothing of course | ||
| aliasToIdentifier = Identifier . G.unName | ||
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| -- | Resolves an 'GR.UnresolvedVal' by converting 'GR.UVPG' values to SQL | ||
| -- expressions that refer to the @result_vars@ input object, collecting information | ||
| -- about various parameters of the query along the way. | ||
| resolveMultiplexedValue | ||
| :: (MonadState QueryParametersInfo m) | ||
| => UnpreparedValue 'Postgres -> m S.SQLExp | ||
| resolveMultiplexedValue = \case | ||
| UVParameter varM colVal -> do | ||
| varJsonPath <- case fmap PS.getName varM of | ||
| Just varName -> do | ||
| modifying qpiReusableVariableValues $ Map.insert varName colVal | ||
| pure ["query", G.unName varName] | ||
| Nothing -> do | ||
| syntheticVarIndex <- use (qpiSyntheticVariableValues . to length) | ||
| modifying qpiSyntheticVariableValues (|> colVal) | ||
| pure ["synthetic", tshow syntheticVarIndex] | ||
| pure $ fromResVars (CollectableTypeScalar $ unsafePGColumnToBackend $ cvType colVal) varJsonPath | ||
| UVSessionVar ty sessVar -> do | ||
| modifying qpiReferencedSessionVariables (Set.insert sessVar) | ||
| pure $ fromResVars ty ["session", sessionVariableToText sessVar] | ||
| UVLiteral sqlExp -> pure sqlExp | ||
| UVSession -> pure $ fromResVars (CollectableTypeScalar PGJSON) ["session"] | ||
| where | ||
| fromResVars pgType jPath = addTypeAnnotation pgType $ S.SEOpApp (S.SQLOp "#>>") | ||
| [ S.SEQIdentifier $ S.QIdentifier (S.QualifiedIdentifier (Identifier "_subs") Nothing) (Identifier "result_vars") | ||
| , S.SEArray $ map S.SELit jPath | ||
| ] | ||
| addTypeAnnotation pgType = flip S.SETyAnn (S.mkTypeAnn pgType) . case pgType of | ||
| CollectableTypeScalar scalarType -> withConstructorFn scalarType | ||
| CollectableTypeArray _ -> id | ||
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| ---------------------------------------------------------------------------------------------------- | ||
| -- Execution | ||
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| executeMultiplexedQuery | ||
| :: (MonadTx m) | ||
| => MultiplexedQuery -> [(CohortId, CohortVariables)] -> m [(CohortId, B.ByteString)] | ||
| executeMultiplexedQuery (MultiplexedQuery query) = executeQuery query | ||
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| -- | Internal; used by both 'executeMultiplexedQuery' and 'explainLiveQueryPlan'. | ||
| executeQuery | ||
| :: (MonadTx m, Q.FromRow a) | ||
| => Q.Query -> [(CohortId, CohortVariables)] -> m [a] | ||
| executeQuery query cohorts = | ||
| let (cohortIds, cohortVars) = unzip cohorts | ||
| preparedArgs = (CohortIdArray cohortIds, CohortVariablesArray cohortVars) | ||
| in liftTx $ Q.listQE defaultTxErrorHandler query preparedArgs True |
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