From a5713ec427f15f2c63eaed14f2a16a952b7ddf06 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 17 Sep 2004 18:28:53 +0000
Subject: [PATCH] Hashed LEFT JOIN would miss outer tuples with no inner match
if the join was large enough to be batched and the tuples fell into a batch
where there were no inner tuples at all. Thanks to Xiaoyu Wang for finding a
test case that exposed this long-standing bug.
---
src/backend/executor/nodeHashjoin.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index fbc55655714..53215be6e91 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeHashjoin.c,v 1.64 2004/08/29 05:06:42 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeHashjoin.c,v 1.65 2004/09/17 18:28:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -603,12 +603,14 @@ ExecHashJoinNewBatch(HashJoinState *hjstate)
}
/*
- * We can skip over any batches that are empty on either side. Release
- * associated temp files right away.
+ * Normally we can skip over any batches that are empty on either side
+ * --- but for JOIN_LEFT, can only skip when left side is empty.
+ * Release associated temp files right away.
*/
while (newbatch <= nbatch &&
- (innerBatchSize[newbatch - 1] == 0L ||
- outerBatchSize[newbatch - 1] == 0L))
+ (outerBatchSize[newbatch - 1] == 0L ||
+ (innerBatchSize[newbatch - 1] == 0L &&
+ hjstate->js.jointype != JOIN_LEFT)))
{
BufFileClose(hashtable->innerBatchFile[newbatch - 1]);
hashtable->innerBatchFile[newbatch - 1] = NULL;
--
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