Separate sending of maxVmemChunksTracked from SendQEDetails, and remove

unnecessary calls of it, to avoid redundant data transmit between QD and QE.

src/backend/gp_libpq_fe/fe-protocol3.c

@@ -171,9 +171,6 @@ pqParseInput3(PGconn *conn)
 			if (pqGetInt(&(conn->motion_listener), 4, conn))
 				return;
 
-			if (pqGetInt64(&(conn->mop_high_watermark), conn))
-				return;
-
 			if (pqGetInt(&version_len, 4, conn))
 				return;
 
@@ -190,6 +187,11 @@ pqParseInput3(PGconn *conn)
 			if (pqGetnchar(conn->qe_version, version_len, conn))
 				return;
 		}
+		else if (id == 'k')
+		{
+			if (pqGetInt64(&(conn->mop_high_watermark), conn))
+				return;
+		}
 		else if (conn->asyncStatus != PGASYNC_BUSY)
 		{
 			/* If not IDLE state, just wait ... */

src/backend/tcop/dest.c

@@ -169,8 +169,6 @@ EndCommand(const char *commandTag, CommandDest dest)
 			 */
 			if (Gp_role == GP_ROLE_EXECUTE)
 			{
-				sendQEDetails();
-
 				pq_beginmessage(&buf, 'C');
 				pq_send_ascii_string(&buf, commandTag);
 				pq_endmessage(&buf);
@@ -252,7 +250,9 @@ ReadyForQuery(CommandDest dest)
 
 				if (Gp_role == GP_ROLE_EXECUTE)
 				{
-					sendQEDetails();
+					pq_beginmessage(&buf, 'k');
+					pq_sendint64(&buf, VmemTracker_GetMaxReservedVmemBytes());
+					pq_endmessage(&buf);
 				}
 
 				pq_beginmessage(&buf, 'Z');
@@ -286,7 +286,6 @@ sendQEDetails(void)
 
 	pq_beginmessage(&buf, 'w');
 	pq_sendint(&buf, (int32) Gp_listener_port, sizeof(int32));			
-	pq_sendint64(&buf, VmemTracker_GetMaxReservedVmemBytes());
 	pq_sendint(&buf, sizeof(PG_VERSION_STR), sizeof(int32));
 	pq_sendbytes(&buf, PG_VERSION_STR, sizeof(PG_VERSION_STR));
 	pq_endmessage(&buf);