database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

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

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

34
src/backend/commands/opclasscmds.c
View File

@ -18,6 +18,7 @@
#include <limits.h>
#include "access/genam.h"
#include "access/hash.h"
#include "access/heapam.h"
#include "access/nbtree.h"
#include "access/htup_details.h"
@ -1129,7 +1130,8 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid)
/*
* btree comparison procs must be 2-arg procs returning int4, while btree
* sortsupport procs must take internal and return void. hash support
* procs must be 1-arg procs returning int4. Otherwise we don't know.
* proc 1 must be a 1-arg proc returning int4, while proc 2 must be a
* 2-arg proc returning int8. Otherwise we don't know.
*/
if (amoid == BTREE_AM_OID)
{
@ -1172,14 +1174,28 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid)
}
else if (amoid == HASH_AM_OID)
{
if (procform->pronargs != 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash procedures must have one argument")));
if (procform->prorettype != INT4OID)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash procedures must return integer")));
if (member->number == HASHSTANDARD_PROC)
{
if (procform->pronargs != 1)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash procedure 1 must have one argument")));
if (procform->prorettype != INT4OID)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash procedure 1 must return integer")));
}
else if (member->number == HASHEXTENDED_PROC)
{
if (procform->pronargs != 2)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash procedure 2 must have two arguments")));
if (procform->prorettype != INT8OID)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash procedure 2 must return bigint")));
}
/*
* If lefttype/righttype isn't specified, use the proc's input type