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/*-------------------------------------------------------------------------
*
* hashutil.c
* Utility code for Postgres hash implementation.
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/hash/hashutil.c,v 1.53 2008/01/01 19:45:46 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/genam.h"
#include "access/hash.h"
#include "access/reloptions.h"
#include "executor/execdebug.h"
#include "utils/lsyscache.h"
/*
* _hash_checkqual -- does the index tuple satisfy the scan conditions?
*/
bool
_hash_checkqual(IndexScanDesc scan, IndexTuple itup)
{
TupleDesc tupdesc = RelationGetDescr(scan->indexRelation);
ScanKey key = scan->keyData;
int scanKeySize = scan->numberOfKeys;
IncrIndexProcessed();
while (scanKeySize > 0)
{
Datum datum;
bool isNull;
Datum test;
datum = index_getattr(itup,
key->sk_attno,
tupdesc,
&isNull);
/* assume sk_func is strict */
if (isNull)
return false;
if (key->sk_flags & SK_ISNULL)
return false;
test = FunctionCall2(&key->sk_func, datum, key->sk_argument);
if (!DatumGetBool(test))
return false;
key++;
scanKeySize--;
}
return true;
}
/*
* _hash_datum2hashkey -- given a Datum, call the index's hash procedure
*
* The Datum is assumed to be of the index's column type, so we can use the
* "primary" hash procedure that's tracked for us by the generic index code.
*/
uint32
_hash_datum2hashkey(Relation rel, Datum key)
{
FmgrInfo *procinfo;
/* XXX assumes index has only one attribute */
procinfo = index_getprocinfo(rel, 1, HASHPROC);
return DatumGetUInt32(FunctionCall1(procinfo, key));
}
/*
* _hash_datum2hashkey_type -- given a Datum of a specified type,
* hash it in a fashion compatible with this index
*
* This is much more expensive than _hash_datum2hashkey, so use it only in
* cross-type situations.
*/
uint32
_hash_datum2hashkey_type(Relation rel, Datum key, Oid keytype)
{
RegProcedure hash_proc;
/* XXX assumes index has only one attribute */
hash_proc = get_opfamily_proc(rel->rd_opfamily[0],
keytype,
keytype,
HASHPROC);
if (!RegProcedureIsValid(hash_proc))
elog(ERROR, "missing support function %d(%u,%u) for index \"%s\"",
HASHPROC, keytype, keytype,
RelationGetRelationName(rel));
return DatumGetUInt32(OidFunctionCall1(hash_proc, key));
}
/*
* _hash_hashkey2bucket -- determine which bucket the hashkey maps to.
*/
Bucket
_hash_hashkey2bucket(uint32 hashkey, uint32 maxbucket,
uint32 highmask, uint32 lowmask)
{
Bucket bucket;
bucket = hashkey & highmask;
if (bucket > maxbucket)
bucket = bucket & lowmask;
return bucket;
}
/*
* _hash_log2 -- returns ceil(lg2(num))
*/
uint32
_hash_log2(uint32 num)
{
uint32 i,
limit;
limit = 1;
for (i = 0; limit < num; limit <<= 1, i++)
;
return i;
}
/*
* _hash_checkpage -- sanity checks on the format of all hash pages
*
* If flags is not zero, it is a bitwise OR of the acceptable values of
* hasho_flag.
*/
void
_hash_checkpage(Relation rel, Buffer buf, int flags)
{
Page page = BufferGetPage(buf);
/*
* ReadBuffer verifies that every newly-read page passes
* PageHeaderIsValid, which means it either contains a reasonably sane
* page header or is all-zero. We have to defend against the all-zero
* case, however.
*/
if (PageIsNew(page))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains unexpected zero page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
/*
* Additionally check that the special area looks sane.
*/
if (((PageHeader) (page))->pd_special !=
(BLCKSZ - MAXALIGN(sizeof(HashPageOpaqueData))))
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains corrupted page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
if (flags)
{
HashPageOpaque opaque = (HashPageOpaque) PageGetSpecialPointer(page);
if ((opaque->hasho_flag & flags) == 0)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" contains corrupted page at block %u",
RelationGetRelationName(rel),
BufferGetBlockNumber(buf)),
errhint("Please REINDEX it.")));
}
/*
* When checking the metapage, also verify magic number and version.
*/
if (flags == LH_META_PAGE)
{
HashMetaPage metap = (HashMetaPage) page;
if (metap->hashm_magic != HASH_MAGIC)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" is not a hash index",
RelationGetRelationName(rel))));
if (metap->hashm_version != HASH_VERSION)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("index \"%s\" has wrong hash version",
RelationGetRelationName(rel)),
errhint("Please REINDEX it.")));
}
}
Datum
hashoptions(PG_FUNCTION_ARGS)
{
Datum reloptions = PG_GETARG_DATUM(0);
bool validate = PG_GETARG_BOOL(1);
bytea *result;
result = default_reloptions(reloptions, validate,
HASH_MIN_FILLFACTOR,
HASH_DEFAULT_FILLFACTOR);
if (result)
PG_RETURN_BYTEA_P(result);
PG_RETURN_NULL();
}
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