diff options
Diffstat (limited to 'src/backend/executor/execGrouping.c')
| -rw-r--r-- | src/backend/executor/execGrouping.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c index 058ee688041..8e8dbb1f205 100644 --- a/src/backend/executor/execGrouping.c +++ b/src/backend/executor/execGrouping.c @@ -23,6 +23,7 @@ #include "executor/executor.h" #include "miscadmin.h" #include "utils/lsyscache.h" +#include "utils/hashutils.h" #include "utils/memutils.h" static uint32 TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple); @@ -326,7 +327,7 @@ BuildTupleHashTable(int numCols, AttrNumber *keyColIdx, * underestimated. */ if (use_variable_hash_iv) - hashtable->hash_iv = hash_uint32(ParallelWorkerNumber); + hashtable->hash_iv = murmurhash32(ParallelWorkerNumber); else hashtable->hash_iv = 0; @@ -510,7 +511,13 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple) } } - return hashkey; + /* + * The way hashes are combined above, among each other and with the IV, + * doesn't lead to good bit perturbation. As the IV's goal is to lead to + * achieve that, perform a round of hashing of the combined hash - + * resulting in near perfect perturbation. + */ + return murmurhash32(hashkey); } /* |