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authorTom Lane2003-01-29 19:37:23 +0000
committerTom Lane2003-01-29 19:37:23 +0000
commitdd10354587c8bf12b0fb501daea96ddcd6167c22 (patch)
tree5c16a1499993d99694b69a07a16578e44495b0cb
parent2357fd166fb1d665af1fe8aceeed9a87829b2217 (diff)
Back-patch fix to avoid integer overflow in ExecHashJoinGetBatch(),
which leads to core dump in large-enough hash joins.
-rw-r--r--src/backend/executor/nodeHash.c36
1 files changed, 23 insertions, 13 deletions
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index bf9bf6eeb0..ed46f54420 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
*
- * $Id: nodeHash.c,v 1.60 2001/10/25 05:49:28 momjian Exp $
+ * $Id: nodeHash.c,v 1.60.2.1 2003/01/29 19:37:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -19,6 +19,7 @@
*/
#include "postgres.h"
+#include <limits.h>
#include <sys/types.h>
#include <math.h>
@@ -343,7 +344,8 @@ ExecChooseHashTableSize(double ntuples, int tupwidth,
{
int tupsize;
double inner_rel_bytes;
- double hash_table_bytes;
+ long hash_table_bytes;
+ double dtmp;
int nbatch;
int nbuckets;
int totalbuckets;
@@ -361,20 +363,22 @@ ExecChooseHashTableSize(double ntuples, int tupwidth,
inner_rel_bytes = ntuples * tupsize * FUDGE_FAC;
/*
- * Target hashtable size is SortMem kilobytes, but not less than
- * sqrt(estimated inner rel size), so as to avoid horrible
- * performance.
+ * Target in-memory hashtable size is SortMem kilobytes.
*/
- hash_table_bytes = sqrt(inner_rel_bytes);
- if (hash_table_bytes < (SortMem * 1024L))
- hash_table_bytes = SortMem * 1024L;
+ hash_table_bytes = SortMem * 1024L;
/*
* Count the number of hash buckets we want for the whole relation,
* for an average bucket load of NTUP_PER_BUCKET (per virtual
- * bucket!).
+ * bucket!). It has to fit in an int, however.
*/
- totalbuckets = (int) ceil(ntuples * FUDGE_FAC / NTUP_PER_BUCKET);
+ dtmp = ceil(ntuples * FUDGE_FAC / NTUP_PER_BUCKET);
+ if (dtmp < INT_MAX)
+ totalbuckets = (int) dtmp;
+ else
+ totalbuckets = INT_MAX;
+ if (totalbuckets <= 0)
+ totalbuckets = 1;
/*
* Count the number of buckets we think will actually fit in the
@@ -408,10 +412,16 @@ ExecChooseHashTableSize(double ntuples, int tupwidth,
* that nbatch doesn't have to have anything to do with the ratio
* totalbuckets/nbuckets; in fact, it is the number of groups we
* will use for the part of the data that doesn't fall into the
- * first nbuckets hash buckets.
+ * first nbuckets hash buckets. We try to set it to make all the
+ * batches the same size. But we have to keep nbatch small
+ * enough to avoid integer overflow in ExecHashJoinGetBatch().
*/
- nbatch = (int) ceil((inner_rel_bytes - hash_table_bytes) /
- hash_table_bytes);
+ dtmp = ceil((inner_rel_bytes - hash_table_bytes) /
+ hash_table_bytes);
+ if (dtmp < INT_MAX / totalbuckets)
+ nbatch = (int) dtmp;
+ else
+ nbatch = INT_MAX / totalbuckets;
if (nbatch <= 0)
nbatch = 1;
}