125bc72 · typeable/postgresql-simple

git.iko.soy/typeable/postgresql-simple

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Minor optimizations of fold's query generation

125bc72Leon P Smith13 years ago

src/Database/PostgreSQL/Simple.hs+9−3

@@ -111,6 +111,7 @@ module Database.PostgreSQL.Simple

111import Blaze.ByteString.Builder

112 ( Builder, fromByteString, toByteString )

113import Blaze.ByteString.Builder.Char8 (fromChar)

114+import Blaze.Text ( integral )

114import Control.Applicative ((<$>), pure)

115import Control.Applicative ((<$>), pure)

115import Control.Exception as E

116import Control.Exception as E

116import Control.Monad (foldM)

117import Control.Monad (foldM)

@@ -482,10 +483,15 @@ doFold FoldOptions{..} conn _template q a0 f = do

482 where

483 where

483 declare = do

484 declare = do

484 name <- newTempName conn

485 name <- newTempName conn

486+ _ <- execute_ conn $ mconcat

485− _ <- execute_ conn $ "DECLARE " <> name <> " NO SCROLL CURSOR FOR " <> q

487+ [ "DECLARE ", name, " NO SCROLL CURSOR FOR ", q ]

486 return name

488 return name

487− fetch name = query_ conn $

489+ fetch (Query name) = query_ conn $

488− "FETCH FORWARD " <> (Query . B.pack . show) chunkSize <> " FROM " <> name

490+ Query (toByteString (fromByteString "FETCH FORWARD "

491+ <> integral chunkSize

492+ <> fromByteString " FROM "

493+ <> fromByteString name

494+ ))

489 close name =

495 close name =

490 (execute_ conn ("CLOSE " <> name) >> return ()) `E.catch` \ex ->

496 (execute_ conn ("CLOSE " <> name) >> return ()) `E.catch` \ex ->

491 -- Don't throw exception if CLOSE failed because the transaction is

497 -- Don't throw exception if CLOSE failed because the transaction is