From: Pavan Deolasee <pavan.deolasee@gmail.com>
Date: Mon, 11 Jan 2016 16:05:28 +0000 (+0530)
Subject: Send XID assigned on a datanode back to the coordinator.
X-Git-Tag: XL9_5_R1BETA1~106
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=79714a871e0e1d7ad18abe623b4987458befead1;p=postgres-xl.git

Send XID assigned on a datanode back to the coordinator.

We'd missed out a case where XIDs are assigned on a datanode, but the same is
not sent back to the coordinator. We now also avoid running a 2PC for
transactions which do not have XID assigned to them since such transactions
must not have made any database changes
---

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 7e564fb655..4a6d3f6152 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -241,6 +241,7 @@ GetNewTransactionId(bool isSubXact)
 			xid = (TransactionId) BeginTranGTM(timestamp, global_session);
 			if (TransactionIdIsValid(xid))
 			{
+				elog(DEBUG2, "Received new XID from GTM: %s:%d", global_session, xid);
 				/*
 				 * Let the coordinator know about GXID assigned to this
 				 * transaction
@@ -264,6 +265,19 @@ GetNewTransactionId(bool isSubXact)
 			 */
 			sprintf(global_session, "%s_%d", PGXCNodeName, MyProcPid);
 			xid = (TransactionId) BeginTranGTM(timestamp, global_session);
+			if (TransactionIdIsValid(xid))
+			{
+				/*
+				 * Let the coordinator know about GXID assigned to this
+				 * transaction
+				 */
+				if (whereToSendOutput == DestRemote &&
+						!IS_PGXC_LOCAL_COORDINATOR)
+				{
+					pq_putmessage('x', (const char *) &xid, sizeof (GlobalTransactionId));
+					IsXidFromGTM = false;
+				}
+			}
 		}
 	}
 	else
diff --git a/src/backend/pgxc/pool/execRemote.c b/src/backend/pgxc/pool/execRemote.c
index 4bf405992c..46fc336e89 100644
--- a/src/backend/pgxc/pool/execRemote.c
+++ b/src/backend/pgxc/pool/execRemote.c
@@ -4064,6 +4064,13 @@ IsTwoPhaseCommitRequired(bool localWrite)
 		return false;
 	}
 
+	/*
+	 * If no XID assigned, no need to run 2PC since neither coordinator nor any
+	 * remote nodes did write operation
+	 */
+	if (!TransactionIdIsValid(GetTopTransactionIdIfAny()))
+		return false;
+
 	handles = get_current_handles();
 	for (i = 0; i < handles->dn_conn_count; i++)
 	{