graphql-engine/server/src-lib/Hasura/GraphQL/Explain.hs
Rakesh Emmadi a8cee16ab5 support aggregations (closes #786) (#787)
* support for count and aggregations on columns, close #786

* support explain query for aggregations

* '<arr-rel>_agg' in '<table>' type, fix order by for aggregations

* add 'allow_aggregations' key in select permissions

* Add checkbox to toggle count and aggregations on columns on select permission

* align aggregation checkbox with columns div

* improve readability of the generated sql

* alias is needed at the top level aggregation

* throw internal errors for unexpected fields

* rename SelFld to more readable TableAggFld

* rename agg to aggregate
2018-10-26 14:32:43 +05:30

127 lines
4.3 KiB
Haskell

{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TemplateHaskell #-}
module Hasura.GraphQL.Explain
( explainGQLQuery
, GQLExplain
) where
import qualified Data.Aeson as J
import qualified Data.Aeson.Casing as J
import qualified Data.Aeson.TH as J
import qualified Data.HashMap.Strict as Map
import qualified Database.PG.Query as Q
import qualified Language.GraphQL.Draft.Syntax as G
import qualified Text.Builder as TB
import qualified Data.ByteString.Lazy as BL
import Hasura.GraphQL.Resolve.Context
import Hasura.GraphQL.Schema
import Hasura.GraphQL.Validate.Field
import Hasura.Prelude
import Hasura.RQL.DML.Internal
import Hasura.RQL.Types
import Hasura.SQL.Types
import Hasura.SQL.Value
import qualified Hasura.GraphQL.Resolve.Select as RS
import qualified Hasura.GraphQL.Transport.HTTP.Protocol as GH
import qualified Hasura.GraphQL.Validate as GV
import qualified Hasura.RQL.DML.Select as RS
import qualified Hasura.Server.Query as RQ
data GQLExplain
= GQLExplain
{ _gqeQuery :: !GH.GraphQLRequest
, _gqeUser :: !UserInfo
} deriving (Show, Eq)
$(J.deriveJSON (J.aesonDrop 4 J.camelCase){J.omitNothingFields=True}
''GQLExplain
)
data FieldPlan
= FieldPlan
{ _fpField :: !G.Name
, _fpSql :: !(Maybe Text)
, _fpPlan :: !(Maybe [Text])
} deriving (Show, Eq)
$(J.deriveJSON (J.aesonDrop 3 J.camelCase) ''FieldPlan)
type Explain =
(ReaderT (FieldMap, OrdByResolveCtx) (Except QErr))
runExplain
:: (MonadError QErr m)
=> (FieldMap, OrdByResolveCtx) -> Explain a -> m a
runExplain ctx m =
either throwError return $ runExcept $ runReaderT m ctx
explainField
:: UserInfo -> GCtx -> Field -> Q.TxE QErr FieldPlan
explainField userInfo gCtx fld =
case fName of
"__type" -> return $ FieldPlan fName Nothing Nothing
"__schema" -> return $ FieldPlan fName Nothing Nothing
"__typename" -> return $ FieldPlan fName Nothing Nothing
_ -> do
opCxt <- getOpCtx fName
sel <- runExplain (fldMap, orderByCtx) $ case opCxt of
OCSelect tn permFilter permLimit hdrs -> do
validateHdrs hdrs
RS.mkSQLSelect False <$>
RS.fromField txtConverter tn permFilter permLimit fld
OCSelectPkey tn permFilter hdrs -> do
validateHdrs hdrs
RS.mkSQLSelect True <$>
RS.fromFieldByPKey txtConverter tn permFilter fld
OCSelectAgg tn permFilter permLimit hdrs -> do
validateHdrs hdrs
RS.mkSQLSelect False <$>
RS.fromAggField txtConverter tn permFilter permLimit fld
_ -> throw500 "unexpected mut field info for explain"
let selectSQL = TB.run $ toSQL sel
withExplain = "EXPLAIN (FORMAT TEXT) " <> selectSQL
planLines <- liftTx $ map runIdentity <$>
Q.listQE dmlTxErrorHandler (Q.fromText withExplain) () True
return $ FieldPlan fName (Just selectSQL) $ Just planLines
where
fName = _fName fld
txtConverter = return . txtEncoder . snd
opCtxMap = _gOpCtxMap gCtx
fldMap = _gFields gCtx
orderByCtx = _gOrdByEnums gCtx
getOpCtx f =
onNothing (Map.lookup f opCtxMap) $ throw500 $
"lookup failed: opctx: " <> showName f
validateHdrs hdrs = do
let receivedHdrs = userVars userInfo
forM_ hdrs $ \hdr ->
unless (Map.member hdr receivedHdrs) $
throw400 NotFound $ hdr <<> " header is expected but not found"
explainGQLQuery
:: (MonadError QErr m, MonadIO m)
=> Q.PGPool
-> Q.TxIsolation
-> GCtxMap
-> GQLExplain
-> m BL.ByteString
explainGQLQuery pool iso gCtxMap (GQLExplain query userInfo)= do
(opTy, selSet) <- runReaderT (GV.validateGQ query) gCtx
unless (opTy == G.OperationTypeQuery) $
throw400 InvalidParams "only queries can be explained"
let tx = mapM (explainField userInfo gCtx) (toList selSet)
plans <- liftIO (runExceptT $ runTx tx) >>= liftEither
return $ J.encode plans
where
gCtx = getGCtx (userRole userInfo) gCtxMap
runTx tx =
Q.runTx pool (iso, Nothing) $ RQ.setHeadersTx userInfo >> tx