1 files changed, 70 insertions, 3 deletions

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6e5891749b4..c3214d4f4d8 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -190,6 +190,7 @@ typedef struct TransactionStateData
 	bool		startedInRecovery;	/* did we start in recovery? */
 	bool		didLogXid;		/* has xid been included in WAL record? */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
+	bool		chain;			/* start a new block after this one */
 	struct TransactionStateData *parent;	/* back link to parent */
 } TransactionStateData;
 
@@ -2775,6 +2776,36 @@ StartTransactionCommand(void)
 	MemoryContextSwitchTo(CurTransactionContext);
 }
 
+
+/*
+ * Simple system for saving and restoring transaction characteristics
+ * (isolation level, read only, deferrable).  We need this for transaction
+ * chaining, so that we can set the characteristics of the new transaction to
+ * be the same as the previous one.  (We need something like this because the
+ * GUC system resets the characteristics at transaction end, so for example
+ * just skipping the reset in StartTransaction() won't work.)
+ */
+static int	save_XactIsoLevel;
+static bool	save_XactReadOnly;
+static bool	save_XactDeferrable;
+
+void
+SaveTransactionCharacteristics(void)
+{
+	save_XactIsoLevel = XactIsoLevel;
+	save_XactReadOnly = XactReadOnly;
+	save_XactDeferrable = XactDeferrable;
+}
+
+void
+RestoreTransactionCharacteristics(void)
+{
+	XactIsoLevel = save_XactIsoLevel;
+	XactReadOnly = save_XactReadOnly;
+	XactDeferrable = save_XactDeferrable;
+}
+
+
 /*
  *	CommitTransactionCommand
  */
@@ -2783,6 +2814,9 @@ CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
+	if (s->chain)
+		SaveTransactionCharacteristics();
+
 	switch (s->blockState)
 	{
 			/*
@@ -2834,6 +2868,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_END:
 			CommitTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2853,6 +2894,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_ABORT_END:
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2864,6 +2912,13 @@ CommitTransactionCommand(void)
 			AbortTransaction();
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -3521,7 +3576,7 @@ PrepareTransactionBlock(const char *gid)
 	bool		result;
 
 	/* Set up to commit the current transaction */
-	result = EndTransactionBlock();
+	result = EndTransactionBlock(false);
 
 	/* If successful, change outer tblock state to PREPARE */
 	if (result)
@@ -3567,7 +3622,7 @@ PrepareTransactionBlock(const char *gid)
  * resource owner, etc while executing inside a Portal.
  */
 bool
-EndTransactionBlock(void)
+EndTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 	bool		result = false;
@@ -3693,6 +3748,13 @@ EndTransactionBlock(void)
 			break;
 	}
 
+	Assert(s->blockState == TBLOCK_STARTED ||
+		   s->blockState == TBLOCK_END ||
+		   s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
+
 	return result;
 }
 
@@ -3703,7 +3765,7 @@ EndTransactionBlock(void)
  * As above, we don't actually do anything here except change blockState.
  */
 void
-UserAbortTransactionBlock(void)
+UserAbortTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 
@@ -3801,6 +3863,11 @@ UserAbortTransactionBlock(void)
 				 BlockStateAsString(s->blockState));
 			break;
 	}
+
+	Assert(s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
 }
 
 /*