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Introduce 64-bit hash functions with a 64-bit seed.

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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
This commit is contained in:
Robert Haas
2017-08-31 22:21:21 -04:00
parent 2d44c58c79
commit 81c5e46c49
33 changed files with 1555 additions and 42 deletions
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4
src/include/utils/typcache.h
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@@ -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