From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 25 Jan 2006 20:44:32 +0000 (+0000)
Subject: Remove unnecessary PQconsumeInput call from PQputCopyData; it's redundant
X-Git-Tag: REL8_2_BETA1~1545
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9b012311f8b6d3596d2a081b8e30b8e8ee352bf2;p=postgresql

Remove unnecessary PQconsumeInput call from PQputCopyData; it's redundant
because pqSendSome will absorb input data anytime it'd be forced to block.
Avoiding a kernel call per PQputCopyData call helps COPY speed materially.

Alon Goldshuv
---

diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index 2b324916df..4edb065c9c 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.178 2006/01/11 08:43:13 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.179 2006/01/25 20:44:32 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1476,13 +1476,13 @@ PQputCopyData(PGconn *conn, const char *buffer, int nbytes)
 	}
 
 	/*
-	 * Check for NOTICE messages coming back from the server.  Since the
-	 * server might generate multiple notices during the COPY, we have to
-	 * consume those in a reasonably prompt fashion to prevent the comm
-	 * buffers from filling up and possibly blocking the server.
+	 * Process any NOTICE or NOTIFY messages that might be pending in the
+	 * input buffer.  Since the server might generate many notices during
+	 * the COPY, we want to clean those out reasonably promptly to prevent
+	 * indefinite expansion of the input buffer.  (Note: the actual read
+	 * of input data into the input buffer happens down inside pqSendSome,
+	 * but it's not authorized to get rid of the data again.)
 	 */
-	if (!PQconsumeInput(conn))
-		return -1;				/* I/O failure */
 	parseInput(conn);
 
 	if (nbytes > 0)