graphql-engine/server/src-lib/Hasura/Backends/MSSQL/Instances/Execute.hs
Rakesh Emmadi 7ca48decfb server/mssql: integrate insert mutation schema parser for MSSQL backend
>

### Description
>
This PR is an incremental work towards [enabling insert mutations on MSSQL](https://github.com/hasura/graphql-engine-mono/pull/1974). In this PR, we generate insert mutation schema parser for MSSQL backend.

### Changelog

- [ ] `CHANGELOG.md` is updated with user-facing content relevant to this PR. If no changelog is required, then add the `no-changelog-required` label.

### Affected components

- [x] Server

https://github.com/hasura/graphql-engine-mono/pull/2141

GitOrigin-RevId: 8595008dece35f7fded9c52e134de8b97b64f53f
2021-08-31 13:35:49 +00:00

342 lines
12 KiB
Haskell

{-# OPTIONS_GHC -fno-warn-orphans #-}
module Hasura.Backends.MSSQL.Instances.Execute
(
MultiplexedQuery'(..),
multiplexRootReselect,
)
where
import Hasura.Prelude
import qualified Data.Aeson.Extended as J
import qualified Data.HashMap.Strict as Map
import qualified Data.HashSet as Set
import qualified Data.List.NonEmpty as NE
import qualified Data.Text.Extended as T
import qualified Database.ODBC.SQLServer as ODBC
import qualified Language.GraphQL.Draft.Syntax as G
import qualified Hasura.RQL.Types.Column as RQL
import qualified Hasura.SQL.AnyBackend as AB
import Hasura.Backends.MSSQL.Connection
import Hasura.Backends.MSSQL.FromIr as TSQL
import Hasura.Backends.MSSQL.Plan
import Hasura.Backends.MSSQL.SQL.Value (txtEncodedColVal)
import Hasura.Backends.MSSQL.ToQuery
import Hasura.Backends.MSSQL.Types as TSQL
import Hasura.Base.Error
import Hasura.EncJSON
import Hasura.GraphQL.Execute.Backend
import Hasura.GraphQL.Execute.LiveQuery.Plan
import Hasura.GraphQL.Parser
import Hasura.QueryTags
import Hasura.RQL.IR
import Hasura.RQL.Types
import Hasura.Session
instance BackendExecute 'MSSQL where
type PreparedQuery 'MSSQL = Text
type MultiplexedQuery 'MSSQL = MultiplexedQuery'
type ExecutionMonad 'MSSQL = ExceptT QErr IO
mkDBQueryPlan = msDBQueryPlan
mkDBMutationPlan = msDBMutationPlan
mkDBSubscriptionPlan = msDBSubscriptionPlan
mkDBQueryExplain = msDBQueryExplain
mkLiveQueryExplain = msDBLiveQueryExplain
-- Multiplexed query
newtype MultiplexedQuery' = MultiplexedQuery' Reselect
instance T.ToTxt MultiplexedQuery' where
toTxt (MultiplexedQuery' reselect) = T.toTxt $ toQueryPretty $ fromReselect reselect
-- Query
msDBQueryPlan
:: forall m.
( MonadError QErr m
)
=> UserInfo
-> SourceName
-> SourceConfig 'MSSQL
-> QueryDB 'MSSQL (Const Void) (UnpreparedValue 'MSSQL)
-> QueryTagsComment
-> m (DBStepInfo 'MSSQL)
msDBQueryPlan userInfo sourceName sourceConfig qrf _queryTags = do
-- TODO (naveen): Append Query Tags to the query
let sessionVariables = _uiSession userInfo
statement <- planQuery sessionVariables qrf
let printer = fromSelect statement
queryString = ODBC.renderQuery $ toQueryPretty printer
pool = _mscConnectionPool sourceConfig
odbcQuery = encJFromText <$> runJSONPathQuery pool (toQueryFlat printer)
pure $ DBStepInfo @'MSSQL sourceName sourceConfig (Just $ queryString) odbcQuery
runShowplan
:: ODBC.Query -> ODBC.Connection -> IO [Text]
runShowplan query conn = do
ODBC.exec conn "SET SHOWPLAN_TEXT ON"
texts <- ODBC.query conn query
ODBC.exec conn "SET SHOWPLAN_TEXT OFF"
-- we don't need to use 'finally' here - if an exception occurs,
-- the connection is removed from the resource pool in 'withResource'.
pure texts
msDBQueryExplain
:: MonadError QErr m
=> G.Name
-> UserInfo
-> SourceName
-> SourceConfig 'MSSQL
-> QueryDB 'MSSQL (Const Void) (UnpreparedValue 'MSSQL)
-> m (AB.AnyBackend DBStepInfo)
msDBQueryExplain fieldName userInfo sourceName sourceConfig qrf = do
let sessionVariables = _uiSession userInfo
statement <- planQuery sessionVariables qrf
let query = toQueryPretty (fromSelect statement)
queryString = ODBC.renderQuery $ query
pool = _mscConnectionPool sourceConfig
odbcQuery =
withMSSQLPool
pool
(\conn -> do
showplan <- runShowplan query conn
pure (encJFromJValue $
ExplainPlan
fieldName
(Just queryString)
(Just showplan)))
pure
$ AB.mkAnyBackend
$ DBStepInfo @'MSSQL sourceName sourceConfig Nothing odbcQuery
msDBLiveQueryExplain
:: (MonadIO m, MonadError QErr m)
=> LiveQueryPlan 'MSSQL (MultiplexedQuery 'MSSQL) -> m LiveQueryPlanExplanation
msDBLiveQueryExplain (LiveQueryPlan plan sourceConfig variables) = do
let (MultiplexedQuery' reselect) = _plqpQuery plan
query = toQueryPretty $ fromSelect $ multiplexRootReselect [(dummyCohortId, variables)] reselect
pool = _mscConnectionPool sourceConfig
explainInfo <- withMSSQLPool pool (runShowplan query)
pure $ LiveQueryPlanExplanation (T.toTxt query) explainInfo variables
--------------------------------------------------------------------------------
-- Producing the correct SQL-level list comprehension to multiplex a query
-- Problem description:
--
-- Generate a query that repeats the same query N times but with
-- certain slots replaced:
--
-- [ Select x y | (x,y) <- [..] ]
--
multiplexRootReselect
:: [(CohortId, CohortVariables)]
-> TSQL.Reselect
-> TSQL.Select
multiplexRootReselect variables rootReselect =
Select
{ selectTop = NoTop
, selectProjections =
[ FieldNameProjection
Aliased
{ aliasedThing =
TSQL.FieldName
{fieldNameEntity = rowAlias, fieldName = resultIdAlias}
, aliasedAlias = resultIdAlias
}
, ExpressionProjection
Aliased
{ aliasedThing =
ColumnExpression
(TSQL.FieldName
{ fieldNameEntity = resultAlias
, fieldName = TSQL.jsonFieldName
})
, aliasedAlias = resultAlias
}
]
, selectFrom =
Just $ FromOpenJson
Aliased
{ aliasedThing =
OpenJson
{ openJsonExpression =
ValueExpression (ODBC.TextValue $ lbsToTxt $ J.encode variables)
, openJsonWith = Just $
NE.fromList
[ UuidField resultIdAlias (Just $ IndexPath RootPath 0)
, JsonField resultVarsAlias (Just $ IndexPath RootPath 1)
]
}
, aliasedAlias = rowAlias
}
, selectJoins =
[ Join
{ joinSource = JoinReselect rootReselect
, joinJoinAlias =
JoinAlias
{ joinAliasEntity = resultAlias
, joinAliasField = Just TSQL.jsonFieldName
}
}
]
, selectWhere = Where mempty
, selectFor =
JsonFor ForJson {jsonCardinality = JsonArray, jsonRoot = NoRoot}
, selectOrderBy = Nothing
, selectOffset = Nothing
}
-- mutation
msDBMutationPlan
:: forall m.
( MonadError QErr m
)
=> UserInfo
-> Bool
-> SourceName
-> SourceConfig 'MSSQL
-> MutationDB 'MSSQL (Const Void) (UnpreparedValue 'MSSQL)
-> QueryTagsComment
-> m (DBStepInfo 'MSSQL)
msDBMutationPlan _userInfo _stringifyNum _sourceName _sourceConfig _mrf _queryTags =
throw400 NotSupported "mutations are not supported in MSSQL"
-- subscription
msDBSubscriptionPlan
:: forall m.
( MonadError QErr m
, MonadIO m
)
=> UserInfo
-> SourceName
-> SourceConfig 'MSSQL
-> InsOrdHashMap G.Name (QueryDB 'MSSQL (Const Void) (UnpreparedValue 'MSSQL))
-> QueryTagsComment
-> m (LiveQueryPlan 'MSSQL (MultiplexedQuery 'MSSQL))
msDBSubscriptionPlan UserInfo {_uiSession, _uiRole} _sourceName sourceConfig rootFields _queryTags = do
-- TODO (naveen): Append query tags to the reselect
(reselect, prepareState) <- planSubscription rootFields _uiSession
cohortVariables <- prepareStateCohortVariables sourceConfig _uiSession prepareState
let parameterizedPlan = ParameterizedLiveQueryPlan _uiRole $ MultiplexedQuery' reselect
pure
$ LiveQueryPlan parameterizedPlan sourceConfig cohortVariables
prepareStateCohortVariables :: (MonadError QErr m, MonadIO m) => SourceConfig 'MSSQL -> SessionVariables -> PrepareState -> m CohortVariables
prepareStateCohortVariables sourceConfig session prepState = do
(namedVars, posVars) <- validateVariables sourceConfig session prepState
let PrepareState{sessionVariables} = prepState
pure $ mkCohortVariables
sessionVariables
session
namedVars
posVars
-- | Ensure that the set of variables (with value instantiations) that occur in
-- a (RQL) query produce a well-formed and executable (SQL) query when
-- considered in isolation.
--
-- This helps avoiding cascading failures in multiplexed queries.
--
-- c.f. https://github.com/hasura/graphql-engine-mono/issues/1210.
validateVariables ::
(MonadError QErr m, MonadIO m) =>
SourceConfig 'MSSQL ->
SessionVariables ->
PrepareState ->
m (ValidatedQueryVariables, ValidatedSyntheticVariables)
validateVariables sourceConfig sessionVariableValues prepState = do
let PrepareState{sessionVariables, namedArguments, positionalArguments} = prepState
-- We generate a single 'canary' query in the form:
--
-- SELECT ... [session].[x-hasura-foo] as [x-hasura-foo], ... as a, ... as b, ...
-- FROM OPENJSON('...')
-- WITH ([x-hasura-foo] NVARCHAR(MAX)) as [session]
--
-- where 'a', 'b', etc. are aliases given to positional arguments.
-- Named arguments and session variables are aliased to themselves.
--
-- The idea being that if the canary query succeeds we can be
-- reasonably confident that adding these variables to a query being
-- polled will not crash the poller.
occSessionVars = filterSessionVariables
(\k _ -> Set.member k sessionVariables)
sessionVariableValues
expSes, expNamed, expPos :: [Aliased Expression]
expSes = sessionReference <$> getSessionVariables occSessionVars
expNamed = map (
\(n, v) -> Aliased (ValueExpression (RQL.cvValue v)) (G.unName n)
)
$ Map.toList $ namedArguments
-- For positional args we need to be a bit careful not to capture names
-- from expNamed and expSes (however unlikely)
expPos = zipWith (\n v -> Aliased (ValueExpression (RQL.cvValue v)) n)
(freshVars (expNamed <> expSes)) positionalArguments
projAll :: [Projection]
projAll = map ExpressionProjection (expSes <> expNamed <> expPos)
canaryQuery = if null projAll
then Nothing
else Just $ renderQuery emptySelect {
selectProjections = projAll,
selectFrom = sessionOpenJson occSessionVars
}
onJust canaryQuery (\q -> do
_ :: [[ODBC.Value]] <- withMSSQLPool (_mscConnectionPool sourceConfig) (`ODBC.query` q)
pure ()
)
pure (ValidatedVariables $ txtEncodedColVal <$> namedArguments,
ValidatedVariables $ txtEncodedColVal <$> positionalArguments)
where
renderQuery :: Select -> ODBC.Query
renderQuery = toQueryFlat . fromSelect
freshVars :: [Aliased a] -> [Text]
freshVars boundNames = filter (not . (`elem` map aliasedAlias boundNames)) chars
-- Infinite list of expression aliases.
chars :: [Text]
chars = [ y T.<>> x | y <- [""] <|> chars, x <- ['a'..'z']]
sessionOpenJson :: SessionVariables -> Maybe From
sessionOpenJson occSessionVars =
nonEmpty (getSessionVariables occSessionVars)
<&> \fields -> FromOpenJson $
Aliased
(
OpenJson
(ValueExpression $ ODBC.TextValue $ lbsToTxt $ J.encode occSessionVars)
(pure (sessField <$> fields))
)
"session"
sessField :: Text -> JsonFieldSpec
sessField var = StringField var Nothing
sessionReference :: Text -> Aliased Expression
sessionReference var = Aliased (ColumnExpression (TSQL.FieldName var "session")) var