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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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6
src/backend/access/hash/hashutil.c
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@@ -85,7 +85,7 @@ _hash_datum2hashkey(Relation rel, Datum key)
Oid collation;
/* XXX assumes index has only one attribute */
procinfo = index_getprocinfo(rel, 1, HASHPROC);
procinfo = index_getprocinfo(rel, 1, HASHSTANDARD_PROC);
collation = rel->rd_indcollation[0];
return DatumGetUInt32(FunctionCall1Coll(procinfo, collation, key));
@@ -108,10 +108,10 @@ _hash_datum2hashkey_type(Relation rel, Datum key, Oid keytype)
hash_proc = get_opfamily_proc(rel->rd_opfamily[0],
keytype,
keytype,
HASHPROC);
HASHSTANDARD_PROC);
if (!RegProcedureIsValid(hash_proc))
elog(ERROR, "missing support function %d(%u,%u) for index \"%s\"",
HASHPROC, keytype, keytype,
HASHSTANDARD_PROC, keytype, keytype,
RelationGetRelationName(rel));
collation = rel->rd_indcollation[0];