add a check to see if contraint exists

cardano-db-sync/src/Cardano/DbSync/Default.hs

@@ -3,10 +3,10 @@
 {-# LANGUAGE ExplicitNamespaces #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# OPTIONS_GHC -Wno-unused-matches #-}
-{-# LANGUAGE RankNTypes #-}
 
 module Cardano.DbSync.Default (
   insertListBlocks,
@@ -79,8 +79,9 @@ applyAndInsertBlockMaybe syncEnv cblk = do
       -- equal, insert the block and restore consistency between ledger and db.
       case eiBlockInDbAlreadyId of
         Left _ -> do
-          liftIO . logInfo tracer $
-            mconcat
+          liftIO
+            . logInfo tracer
+            $ mconcat
               [ "Received block which is not in the db with "
               , textShow (getHeaderFields cblk)
               , ". Time to restore consistency."
@@ -93,7 +94,6 @@ applyAndInsertBlockMaybe syncEnv cblk = do
           -- we can put the constraints on rewards table
           lift addRewardTableConstraint
           lift addEpochStakeTableConstraint
-
         Right blockId | Just (adaPots, slotNo, epochNo) <- getAdaPots applyRes -> do
           replaced <- lift $ DB.replaceAdaPots blockId $ mkAdaPots blockId slotNo epochNo adaPots
           if replaced
@@ -125,7 +125,7 @@ applyAndInsertBlockMaybe syncEnv cblk = do
       Generic.neEpoch <$> maybeFromStrict (apNewEpoch appRes)
 
 addRewardTableConstraint ::
-  forall m. ( MonadBaseControl IO m , MonadIO m) => ReaderT SqlBackend m ()
+  forall m. (MonadBaseControl IO m, MonadIO m) => ReaderT SqlBackend m ()
 addRewardTableConstraint = do
   let entityD = entityDef $ Proxy @DB.Reward
   DB.alterTable
@@ -140,7 +140,7 @@ addRewardTableConstraint = do
     )
 
 addEpochStakeTableConstraint ::
-  forall m. ( MonadBaseControl IO m , MonadIO m) => ReaderT SqlBackend m ()
+  forall m. (MonadBaseControl IO m, MonadIO m) => ReaderT SqlBackend m ()
 addEpochStakeTableConstraint = do
   let entityD = entityDef $ Proxy @DB.EpochStake
   DB.alterTable
@@ -215,8 +215,9 @@ insertBlock syncEnv cblk applyRes firstAfterRollback tookSnapshot = do
   -- update the epoch
   updateEpoch details isNewEpochEvent
   whenPruneTxOut syncEnv $
-    when (unBlockNo blkNo `mod` getPruneInterval syncEnv == 0) $ do
-      lift $ DB.deleteConsumedTxOut tracer (getSafeBlockNoDiff syncEnv)
+    when (unBlockNo blkNo `mod` getPruneInterval syncEnv == 0) $
+      do
+        lift $ DB.deleteConsumedTxOut tracer (getSafeBlockNoDiff syncEnv)
   lift $ commitOrIndexes withinTwoMin withinHalfHour
   where
     tracer = getTrace syncEnv

cardano-db/src/Cardano/Db.hs

@@ -13,10 +13,10 @@ module Cardano.Db (
   queryTxOutConsumedCount,
 ) where
 
+import Cardano.Db.AlterTable as X
 import Cardano.Db.Delete as X
 import Cardano.Db.Error as X
 import Cardano.Db.Insert as X
-import Cardano.Db.AlterTable as X
 import Cardano.Db.Migration as X
 import Cardano.Db.Migration.Extra.CosnumedTxOut.Queries (isMigrated, migrateTxOut, queryTxOutConsumedCount, queryTxOutConsumedNullCount)
 import Cardano.Db.Migration.Version as X

cardano-db/src/Cardano/Db/AlterTable.hs

@@ -6,8 +6,8 @@
 {-# OPTIONS_GHC -Wno-unused-local-binds #-}
 
 module Cardano.Db.AlterTable (
-  AlterTable(..),
-  DbAlterTableException(..),
+  AlterTable (..),
+  DbAlterTableException (..),
   alterTable,
 ) where
 
@@ -16,9 +16,9 @@ import Control.Monad.IO.Class (MonadIO, liftIO)
 import Control.Monad.Trans.Control (MonadBaseControl)
 import Control.Monad.Trans.Reader (ReaderT)
 import qualified Data.Text as T
-import Database.Persist.Postgresql (ConstraintNameDB (..), EntityNameDB (..), FieldNameDB (..), SqlBackend, rawExecute, EntityDef, getEntityFields, fieldDB)
-import Database.PostgreSQL.Simple (SqlError (..), ExecStatus (..))
 import Database.Persist.EntityDef.Internal (entityDB)
+import Database.Persist.Postgresql (ConstraintNameDB (..), EntityDef, EntityNameDB (..), FieldNameDB (..), Single (..), SqlBackend, fieldDB, getEntityFields, rawExecute, rawSql)
+import Database.PostgreSQL.Simple (ExecStatus (..), SqlError (..))
 
 -- The ability to `ALTER TABLE` currently dealing with `CONSTRAINT` but can be extended
 data AlterTable
@@ -36,29 +36,48 @@ alterTable ::
   forall m.
   ( MonadBaseControl IO m
   , MonadIO m
+  , MonadFail m
   ) =>
   EntityDef ->
   AlterTable ->
   ReaderT SqlBackend m ()
 alterTable entity (AddUniqueConstraint cname cols) = do
-  -- Check that input fields are indeed present
+  -- Check that entity fields are in the schema
   if checkAllFieldsValid entity cols
-    then handle alterTableExceptHandler (rawExecute query [])
-    else liftIO $ throwIO (DbAlterTableException "Constraint field does not exist" sqlError)
+    then do
+      -- check if the constraint name already exists
+      constraintRes <- queryConstraint cname
+      if constraintRes == "1"
+        then throwErr "Constraint field already exist"
+        else -- if it doesn't exist then add a new constraint
+          handle alterTableExceptHandler (rawExecute queryAddConstraint [])
+    else error "Some of the unique values which you are being added to the constraint don't correlate"
   where
-    query :: T.Text
-    query =
+    queryAddConstraint :: T.Text
+    queryAddConstraint =
       T.concat
         [ "ALTER TABLE "
         , unEntityNameDB (entityDB entity)
-        , " ADD CONSTRAINT IF NOT EXISTS "
+        , " ADD CONSTRAINT "
         , unConstraintNameDB cname
         , " UNIQUE("
         , T.intercalate "," $ map escapeDBName' cols
         , ")"
         ]
+
     escapeDBName' :: FieldNameDB -> T.Text
     escapeDBName' name = unFieldNameDB name
+
+    throwErr :: forall m'. (MonadIO m') => [Char] -> ReaderT SqlBackend m' ()
+    throwErr e = liftIO $ throwIO (DbAlterTableException e sqlError)
+
+    queryCheckConstraint :: T.Text
+    queryCheckConstraint =
+      T.concat
+        [ "SELECT COUNT(*) FROM pg_constraint WHERE conname ='"
+        , unConstraintNameDB cname
+        , "'"
+        ]
 alterTable entity (DropUniqueConstraint cname) =
   handle alterTableExceptHandler (rawExecute query [])
   where
@@ -71,6 +90,18 @@ alterTable entity (DropUniqueConstraint cname) =
         , unConstraintNameDB cname
         ]
 
+-- check if a constraint is already present
+queryConstraint ::
+  ( MonadIO m
+  , MonadFail m
+  ) =>
+  ConstraintNameDB ->
+  ReaderT SqlBackend m T.Text
+queryConstraint cname = do
+  let query = T.concat ["SELECT 1 FROM pg_constraint WHERE conname ='", unConstraintNameDB cname, "'"]
+  [Single constraintNum] <- rawSql query []
+  pure constraintNum
+
 -- check to see that the field inputs exist
 checkAllFieldsValid :: Foldable t => EntityDef -> t FieldNameDB -> Bool
 checkAllFieldsValid entity cols = do
@@ -86,10 +117,11 @@ alterTableExceptHandler ::
 alterTableExceptHandler e = liftIO $ throwIO (DbAlterTableException "" e)
 
 sqlError :: SqlError
-sqlError = SqlError
-  { sqlState = ""
-  , sqlExecStatus = FatalError
-  , sqlErrorMsg = ""
-  , sqlErrorDetail = ""
-  , sqlErrorHint = ""
-  }
+sqlError =
+  SqlError
+    { sqlState = ""
+    , sqlExecStatus = FatalError
+    , sqlErrorMsg = ""
+    , sqlErrorDetail = ""
+    , sqlErrorHint = ""
+    }

cardano-db/src/Cardano/Db/Insert.hs

@@ -111,14 +111,15 @@ import Database.Persist.Sql (
   SqlBackend,
   UniqueDef,
   entityDef,
+  getEntityForeignDefs,
   insertMany,
   rawExecute,
   rawSql,
   replace,
   toPersistFields,
   toPersistValue,
   uniqueDBName,
-  uniqueFields, getEntityForeignDefs,
+  uniqueFields,
  )
 import qualified Database.Persist.Sql.Util as Util
 import Database.Persist.Types (