diff options
Diffstat (limited to 'src/backend/executor/nodeHash.c')
| -rw-r--r-- | src/backend/executor/nodeHash.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c index a40423179d1..826cafe8737 100644 --- a/src/backend/executor/nodeHash.c +++ b/src/backend/executor/nodeHash.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.96.2.2 2005/11/23 20:28:04 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.96.2.3 2007/06/01 15:58:09 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -20,6 +20,7 @@ */ #include "postgres.h" +#include "access/hash.h" #include "executor/execdebug.h" #include "executor/hashjoin.h" #include "executor/instrument.h" @@ -713,9 +714,11 @@ ExecHashGetHashValue(HashJoinTable hashtable, * chains), and must only cause the batch number to remain the same or * increase. Our algorithm is * bucketno = hashvalue MOD nbuckets - * batchno = (hashvalue DIV nbuckets) MOD nbatch - * where nbuckets should preferably be prime so that all bits of the - * hash value can affect both bucketno and batchno. + * batchno = hash_uint32(hashvalue) MOD nbatch + * which gives reasonably independent bucket and batch numbers in the face + * of some rather poorly-implemented hash functions in hashfunc.c. (This + * will change in PG 8.3.) + * * nbuckets doesn't change over the course of the join. * * nbatch is always a power of 2; we increase it only by doubling it. This @@ -734,7 +737,7 @@ ExecHashGetBucketAndBatch(HashJoinTable hashtable, { *bucketno = hashvalue % nbuckets; /* since nbatch is a power of 2, can do MOD by masking */ - *batchno = (hashvalue / nbuckets) & (nbatch - 1); + *batchno = hash_uint32(hashvalue) & (nbatch - 1); } else { |