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| author | Robert Haas <rhaas@postgresql.org> | 2017-08-31 22:21:21 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2017-08-31 22:21:21 -0400 |
| commit | 81c5e46c490e2426db243eada186995da5bb0ba7 (patch) | |
| tree | a6cb745131c45a06fa43746a17a69e1dc9daa44a /src/include/utils/typcache.h | |
| parent | 2d44c58c79aeef2d376be0141057afbb9ec6b5bc (diff) | |
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
Diffstat (limited to 'src/include/utils/typcache.h')
| -rw-r--r-- | src/include/utils/typcache.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/include/utils/typcache.h b/src/include/utils/typcache.h index c12631dafe2..b4f75921625 100644 --- a/src/include/utils/typcache.h +++ b/src/include/utils/typcache.h @@ -56,6 +56,7 @@ typedef struct TypeCacheEntry Oid gt_opr; /* the greater-than operator */ Oid cmp_proc; /* the btree comparison function */ Oid hash_proc; /* the hash calculation function */ + Oid hash_extended_proc; /* the extended hash calculation function */ /* * Pre-set-up fmgr call info for the equality operator, the btree @@ -67,6 +68,7 @@ typedef struct TypeCacheEntry FmgrInfo eq_opr_finfo; FmgrInfo cmp_proc_finfo; FmgrInfo hash_proc_finfo; + FmgrInfo hash_extended_proc_finfo; /* * Tuple descriptor if it's a composite type (row type). NULL if not @@ -120,6 +122,8 @@ typedef struct TypeCacheEntry #define TYPECACHE_HASH_OPFAMILY 0x0400 #define TYPECACHE_RANGE_INFO 0x0800 #define TYPECACHE_DOMAIN_INFO 0x1000 +#define TYPECACHE_HASH_EXTENDED_PROC 0x2000 +#define TYPECACHE_HASH_EXTENDED_PROC_FINFO 0x4000 /* * Callers wishing to maintain a long-lived reference to a domain's constraint |