greenplumn cdbhash 源码
greenplumn cdbhash 代码
文件路径：/src/include/cdb/cdbhash.h
/*--------------------------------------------------------------------------
*
* cdbhash.h
* Definitions and API functions for cdbhash.c
*
* Portions Copyright (c) 2005-2008, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
*
*
* IDENTIFICATION
* src/include/cdb/cdbhash.h
*
*--------------------------------------------------------------------------
*/
#ifndef CDBHASH_H
#define CDBHASH_H
#include "utils/rel.h"
/* GUC */
extern bool gp_use_legacy_hashops;
/*
* reduction methods.
*/
typedef enum
{
REDUCE_LAZYMOD = 1,
REDUCE_BITMASK,
REDUCE_JUMP_HASH
} CdbHashReduce;
/*
* Structure that holds Greenplum Database hashing information.
*/
typedef struct CdbHash
{
uint32 hash; /* The result hash value */
int numsegs; /* number of segments in Greenplum Database used for
* partitioning */
CdbHashReduce reducealg; /* the algorithm used for reducing to buckets */
bool is_legacy_hash;
int natts;
FmgrInfo *hashfuncs;
} CdbHash;
/*
* Create and initialize a CdbHash in the current memory context.
*/
extern CdbHash *makeCdbHash(int numsegs, int natts, Oid *typeoids);
extern CdbHash *makeCdbHashForRelation(Relation rel);
/*
* Initialize CdbHash for hashing the next tuple values.
*/
extern void cdbhashinit(CdbHash *h);
/*
* Add an attribute to the hash calculation.
*/
extern void cdbhash(CdbHash *h, int attno, Datum datum, bool isnull);
/*
* Reduce the hash to a segment number.
*/
extern unsigned int cdbhashreduce(CdbHash *h);
/*
* Return a random segment number, for a randomly distributed policy.
*/
extern unsigned int cdbhashrandomseg(int numsegs);
/*
* Catalog lookup functions related to distribution keys and hash opclasses.
*/
extern Oid cdb_get_opclass_for_column_def(List *opclass, Oid attrType);
extern Oid cdb_default_distribution_opfamily_for_type(Oid typid);
extern Oid cdb_default_distribution_opclass_for_type(Oid typid);
extern Oid cdb_hashproc_in_opfamily(Oid opfamily, Oid typeoid);
extern Oid cdb_eqop_in_hash_opfamily(Oid opfamily, Oid typeoid);
/* prototypes and other things, from cdblegacyhash.c */
/* 32 bit FNV-1 non-zero initial basis */
#define FNV1_32_INIT ((uint32)0x811c9dc5)
extern uint32 magic_hash_stash;
extern bool isLegacyCdbHashFunction(Oid funcid);
extern Oid get_legacy_cdbhash_opclass_for_base_type(Oid typid);
extern uint32 cdblegacyhash_null(void);
#endif /* CDBHASH_H */
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