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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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58
src/backend/utils/cache/typcache.c vendored
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@@ -90,6 +90,7 @@ static TypeCacheEntry *firstDomainTypeEntry = NULL;
#define TCFLAGS_HAVE_FIELD_EQUALITY 0x1000
#define TCFLAGS_HAVE_FIELD_COMPARE 0x2000
#define TCFLAGS_CHECKED_DOMAIN_CONSTRAINTS 0x4000
#define TCFLAGS_CHECKED_HASH_EXTENDED_PROC 0x8000
/*
* Data stored about a domain type's constraints. Note that we do not create
@@ -307,6 +308,8 @@ lookup_type_cache(Oid type_id, int flags)
flags |= TYPECACHE_HASH_OPFAMILY;
if ((flags & (TYPECACHE_HASH_PROC | TYPECACHE_HASH_PROC_FINFO |
TYPECACHE_HASH_EXTENDED_PROC |
TYPECACHE_HASH_EXTENDED_PROC_FINFO |
TYPECACHE_HASH_OPFAMILY)) &&
!(typentry->flags & TCFLAGS_CHECKED_HASH_OPCLASS))
{
@@ -329,6 +332,7 @@ lookup_type_cache(Oid type_id, int flags)
* decision is still good.
*/
typentry->flags &= ~(TCFLAGS_CHECKED_HASH_PROC);
typentry->flags &= ~(TCFLAGS_CHECKED_HASH_EXTENDED_PROC);
typentry->flags |= TCFLAGS_CHECKED_HASH_OPCLASS;
}
@@ -372,11 +376,12 @@ lookup_type_cache(Oid type_id, int flags)
typentry->eq_opr = eq_opr;
/*
* Reset info about hash function whenever we pick up new info about
* equality operator. This is so we can ensure that the hash function
* matches the operator.
* Reset info about hash functions whenever we pick up new info about
* equality operator. This is so we can ensure that the hash functions
* match the operator.
*/
typentry->flags &= ~(TCFLAGS_CHECKED_HASH_PROC);
typentry->flags &= ~(TCFLAGS_CHECKED_HASH_EXTENDED_PROC);
typentry->flags |= TCFLAGS_CHECKED_EQ_OPR;
}
if ((flags & TYPECACHE_LT_OPR) &&
@@ -467,7 +472,7 @@ lookup_type_cache(Oid type_id, int flags)
hash_proc = get_opfamily_proc(typentry->hash_opf,
typentry->hash_opintype,
typentry->hash_opintype,
HASHPROC);
HASHSTANDARD_PROC);
/*
* As above, make sure hash_array will succeed. We don't currently
@@ -485,6 +490,43 @@ lookup_type_cache(Oid type_id, int flags)
typentry->hash_proc = hash_proc;
typentry->flags |= TCFLAGS_CHECKED_HASH_PROC;
}
if ((flags & (TYPECACHE_HASH_EXTENDED_PROC |
TYPECACHE_HASH_EXTENDED_PROC_FINFO)) &&
!(typentry->flags & TCFLAGS_CHECKED_HASH_EXTENDED_PROC))
{
Oid hash_extended_proc = InvalidOid;
/*
* We insist that the eq_opr, if one has been determined, match the
* hash opclass; else report there is no hash function.
*/
if (typentry->hash_opf != InvalidOid &&
(!OidIsValid(typentry->eq_opr) ||
typentry->eq_opr == get_opfamily_member(typentry->hash_opf,
typentry->hash_opintype,
typentry->hash_opintype,
HTEqualStrategyNumber)))
hash_extended_proc = get_opfamily_proc(typentry->hash_opf,
typentry->hash_opintype,
typentry->hash_opintype,
HASHEXTENDED_PROC);
/*
* As above, make sure hash_array_extended will succeed. We don't
* currently support hashing for composite types, but when we do,
* we'll need more logic here to check that case too.
*/
if (hash_extended_proc == F_HASH_ARRAY_EXTENDED &&
!array_element_has_hashing(typentry))
hash_extended_proc = InvalidOid;
/* Force update of hash_proc_finfo only if we're changing state */
if (typentry->hash_extended_proc != hash_extended_proc)
typentry->hash_extended_proc_finfo.fn_oid = InvalidOid;
typentry->hash_extended_proc = hash_extended_proc;
typentry->flags |= TCFLAGS_CHECKED_HASH_EXTENDED_PROC;
}
/*
* Set up fmgr lookup info as requested
@@ -523,6 +565,14 @@ lookup_type_cache(Oid type_id, int flags)
fmgr_info_cxt(typentry->hash_proc, &typentry->hash_proc_finfo,
CacheMemoryContext);
}
if ((flags & TYPECACHE_HASH_EXTENDED_PROC_FINFO) &&
typentry->hash_extended_proc_finfo.fn_oid == InvalidOid &&
typentry->hash_extended_proc != InvalidOid)
{
fmgr_info_cxt(typentry->hash_extended_proc,
&typentry->hash_extended_proc_finfo,
CacheMemoryContext);
}
/*
* If it's a composite type (row type), get tupdesc if requested