Avoid running out of memory during hash_create, by not passing a

number-of-buckets that exceeds the size we actually plan to allow
the hash table to grow to.  Per trouble report from Sean Shanny.

diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 37fca4c..0ece6c6 100644 (file)
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/executor/nodeIndexscan.c,v 1.87 2003/11/29 19:51:48 pgsql Exp $
+ *       $PostgreSQL: pgsql/src/backend/executor/nodeIndexscan.c,v 1.88 2003/12/30 20:05:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -953,22 +953,28 @@ static void
 create_duphash(IndexScanState *node)
 {
        HASHCTL         hash_ctl;
+       long            nbuckets;
 
+       node->iss_MaxHash = (SortMem * 1024L) /
+               (MAXALIGN(sizeof(HASHELEMENT)) + MAXALIGN(sizeof(DupHashTabEntry)));
        MemSet(&hash_ctl, 0, sizeof(hash_ctl));
        hash_ctl.keysize = SizeOfIptrData;
        hash_ctl.entrysize = sizeof(DupHashTabEntry);
        hash_ctl.hash = tag_hash;
        hash_ctl.hcxt = CurrentMemoryContext;
+       nbuckets = (long) ceil(node->ss.ps.plan->plan_rows);
+       if (nbuckets < 1)
+               nbuckets = 1;
+       if (nbuckets > node->iss_MaxHash)
+               nbuckets = node->iss_MaxHash;
        node->iss_DupHash = hash_create("DupHashTable",
-                                                                       (long) ceil(node->ss.ps.plan->plan_rows),
+                                                                       nbuckets,
                                                                        &hash_ctl,
                                                                        HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT);
        if (node->iss_DupHash == NULL)
                ereport(ERROR,
                                (errcode(ERRCODE_OUT_OF_MEMORY),
                                 errmsg("out of memory")));
-       node->iss_MaxHash = (SortMem * 1024L) /
-               (MAXALIGN(sizeof(HASHELEMENT)) + MAXALIGN(sizeof(DupHashTabEntry)));
 }
 
 int