From 81c5e46c490e2426db243eada186995da5bb0ba7 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Thu, 31 Aug 2017 22:21:21 -0400 Subject: Introduce 64-bit hash functions with a 64-bit seed. This will be useful for hash partitioning, which needs a way to seed the hash functions to avoid problems such as a hash index on a hash partitioned table clumping all values into a small portion of the bucket space; it's also useful for anything that wants a 64-bit hash value rather than a 32-bit hash value. Just in case somebody wants a 64-bit hash value that is compatible with the existing 32-bit hash values, make the low 32-bits of the 64-bit hash value match the 32-bit hash value when the seed is 0. Robert Haas and Amul Sul Discussion: http://postgr.es/m/CA+Tgmoafx2yoJuhCQQOL5CocEi-w_uG4S2xT0EtgiJnPGcHW3g@mail.gmail.com --- src/backend/utils/adt/uuid.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'src/backend/utils/adt/uuid.c') diff --git a/src/backend/utils/adt/uuid.c b/src/backend/utils/adt/uuid.c index 5f15c8e6196..f73c695878d 100644 --- a/src/backend/utils/adt/uuid.c +++ b/src/backend/utils/adt/uuid.c @@ -408,3 +408,11 @@ uuid_hash(PG_FUNCTION_ARGS) return hash_any(key->data, UUID_LEN); } + +Datum +uuid_hash_extended(PG_FUNCTION_ARGS) +{ + pg_uuid_t *key = PG_GETARG_UUID_P(0); + + return hash_any_extended(key->data, UUID_LEN, PG_GETARG_INT64(1)); +} -- cgit v1.2.3