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blue-lemon0104
360
pg_include/access/hash.h
Executable file
360
pg_include/access/hash.h
Executable file
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/*-------------------------------------------------------------------------
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*
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* hash.h
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* header file for postgres hash access method implementation
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*
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*
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* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/hash.h
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*
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* NOTES
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* modeled after Margo Seltzer's hash implementation for unix.
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef HASH_H
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#define HASH_H
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#include "access/genam.h"
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#include "access/itup.h"
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#include "access/sdir.h"
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#include "access/xlog.h"
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#include "fmgr.h"
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#include "storage/bufmgr.h"
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#include "storage/lock.h"
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#include "utils/relcache.h"
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/*
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* Mapping from hash bucket number to physical block number of bucket's
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* starting page. Beware of multiple evaluations of argument!
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*/
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typedef uint32 Bucket;
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#define BUCKET_TO_BLKNO(metap,B) \
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((BlockNumber) ((B) + ((B) ? (metap)->hashm_spares[_hash_log2((B)+1)-1] : 0)) + 1)
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/*
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* Special space for hash index pages.
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*
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* hasho_flag tells us which type of page we're looking at. For
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* example, knowing overflow pages from bucket pages is necessary
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* information when you're deleting tuples from a page. If all the
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* tuples are deleted from an overflow page, the overflow is made
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* available to other buckets by calling _hash_freeovflpage(). If all
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* the tuples are deleted from a bucket page, no additional action is
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* necessary.
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*/
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#define LH_UNUSED_PAGE (0)
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#define LH_OVERFLOW_PAGE (1 << 0)
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#define LH_BUCKET_PAGE (1 << 1)
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#define LH_BITMAP_PAGE (1 << 2)
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#define LH_META_PAGE (1 << 3)
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typedef struct HashPageOpaqueData
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{
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BlockNumber hasho_prevblkno; /* previous ovfl (or bucket) blkno */
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BlockNumber hasho_nextblkno; /* next ovfl blkno */
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Bucket hasho_bucket; /* bucket number this pg belongs to */
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uint16 hasho_flag; /* page type code, see above */
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uint16 hasho_page_id; /* for identification of hash indexes */
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} HashPageOpaqueData;
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typedef HashPageOpaqueData *HashPageOpaque;
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/*
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* The page ID is for the convenience of pg_filedump and similar utilities,
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* which otherwise would have a hard time telling pages of different index
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* types apart. It should be the last 2 bytes on the page. This is more or
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* less "free" due to alignment considerations.
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*/
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#define HASHO_PAGE_ID 0xFF80
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/*
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* HashScanOpaqueData is private state for a hash index scan.
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*/
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typedef struct HashScanOpaqueData
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{
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/* Hash value of the scan key, ie, the hash key we seek */
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uint32 hashso_sk_hash;
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/*
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* By definition, a hash scan should be examining only one bucket. We
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* record the bucket number here as soon as it is known.
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*/
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Bucket hashso_bucket;
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bool hashso_bucket_valid;
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/*
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* If we have a share lock on the bucket, we record it here. When
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* hashso_bucket_blkno is zero, we have no such lock.
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*/
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BlockNumber hashso_bucket_blkno;
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/*
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* We also want to remember which buffer we're currently examining in the
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* scan. We keep the buffer pinned (but not locked) across hashgettuple
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* calls, in order to avoid doing a ReadBuffer() for every tuple in the
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* index.
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*/
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Buffer hashso_curbuf;
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/* Current position of the scan, as an index TID */
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ItemPointerData hashso_curpos;
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/* Current position of the scan, as a heap TID */
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ItemPointerData hashso_heappos;
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} HashScanOpaqueData;
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typedef HashScanOpaqueData *HashScanOpaque;
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/*
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* Definitions for metapage.
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*/
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#define HASH_METAPAGE 0 /* metapage is always block 0 */
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#define HASH_MAGIC 0x6440640
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#define HASH_VERSION 2 /* 2 signifies only hash key value is stored */
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/*
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* Spares[] holds the number of overflow pages currently allocated at or
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* before a certain splitpoint. For example, if spares[3] = 7 then there are
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* 7 ovflpages before splitpoint 3 (compare BUCKET_TO_BLKNO macro). The
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* value in spares[ovflpoint] increases as overflow pages are added at the
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* end of the index. Once ovflpoint increases (ie, we have actually allocated
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* the bucket pages belonging to that splitpoint) the number of spares at the
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* prior splitpoint cannot change anymore.
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*
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* ovflpages that have been recycled for reuse can be found by looking at
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* bitmaps that are stored within ovflpages dedicated for the purpose.
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* The blknos of these bitmap pages are kept in bitmaps[]; nmaps is the
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* number of currently existing bitmaps.
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*
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* The limitation on the size of spares[] comes from the fact that there's
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* no point in having more than 2^32 buckets with only uint32 hashcodes.
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* There is no particular upper limit on the size of mapp[], other than
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* needing to fit into the metapage. (With 8K block size, 128 bitmaps
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* limit us to 64 Gb of overflow space...)
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*/
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#define HASH_MAX_SPLITPOINTS 32
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#define HASH_MAX_BITMAPS 128
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typedef struct HashMetaPageData
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{
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uint32 hashm_magic; /* magic no. for hash tables */
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uint32 hashm_version; /* version ID */
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double hashm_ntuples; /* number of tuples stored in the table */
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uint16 hashm_ffactor; /* target fill factor (tuples/bucket) */
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uint16 hashm_bsize; /* index page size (bytes) */
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uint16 hashm_bmsize; /* bitmap array size (bytes) - must be a power
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* of 2 */
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uint16 hashm_bmshift; /* log2(bitmap array size in BITS) */
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uint32 hashm_maxbucket; /* ID of maximum bucket in use */
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uint32 hashm_highmask; /* mask to modulo into entire table */
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uint32 hashm_lowmask; /* mask to modulo into lower half of table */
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uint32 hashm_ovflpoint;/* splitpoint from which ovflpgs being
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* allocated */
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uint32 hashm_firstfree; /* lowest-number free ovflpage (bit#) */
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uint32 hashm_nmaps; /* number of bitmap pages */
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RegProcedure hashm_procid; /* hash procedure id from pg_proc */
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uint32 hashm_spares[HASH_MAX_SPLITPOINTS]; /* spare pages before
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* each splitpoint */
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BlockNumber hashm_mapp[HASH_MAX_BITMAPS]; /* blknos of ovfl bitmaps */
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} HashMetaPageData;
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typedef HashMetaPageData *HashMetaPage;
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/*
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* Maximum size of a hash index item (it's okay to have only one per page)
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*/
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#define HashMaxItemSize(page) \
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MAXALIGN_DOWN(PageGetPageSize(page) - \
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SizeOfPageHeaderData - \
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sizeof(ItemIdData) - \
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MAXALIGN(sizeof(HashPageOpaqueData)))
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#define HASH_MIN_FILLFACTOR 10
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#define HASH_DEFAULT_FILLFACTOR 75
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/*
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* Constants
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*/
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#define BYTE_TO_BIT 3 /* 2^3 bits/byte */
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#define ALL_SET ((uint32) ~0)
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/*
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* Bitmap pages do not contain tuples. They do contain the standard
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* page headers and trailers; however, everything in between is a
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* giant bit array. The number of bits that fit on a page obviously
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* depends on the page size and the header/trailer overhead. We require
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* the number of bits per page to be a power of 2.
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*/
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#define BMPGSZ_BYTE(metap) ((metap)->hashm_bmsize)
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#define BMPGSZ_BIT(metap) ((metap)->hashm_bmsize << BYTE_TO_BIT)
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#define BMPG_SHIFT(metap) ((metap)->hashm_bmshift)
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#define BMPG_MASK(metap) (BMPGSZ_BIT(metap) - 1)
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#define HashPageGetBitmap(page) \
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((uint32 *) PageGetContents(page))
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#define HashGetMaxBitmapSize(page) \
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(PageGetPageSize((Page) page) - \
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(MAXALIGN(SizeOfPageHeaderData) + MAXALIGN(sizeof(HashPageOpaqueData))))
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#define HashPageGetMeta(page) \
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((HashMetaPage) PageGetContents(page))
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/*
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* The number of bits in an ovflpage bitmap word.
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*/
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#define BITS_PER_MAP 32 /* Number of bits in uint32 */
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/* Given the address of the beginning of a bit map, clear/set the nth bit */
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#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
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#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
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#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
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/*
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* page-level and high-level locking modes (see README)
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*/
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#define HASH_READ BUFFER_LOCK_SHARE
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#define HASH_WRITE BUFFER_LOCK_EXCLUSIVE
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#define HASH_NOLOCK (-1)
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#define HASH_SHARE ShareLock
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#define HASH_EXCLUSIVE ExclusiveLock
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/*
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* Strategy number. There's only one valid strategy for hashing: equality.
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*/
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#define HTEqualStrategyNumber 1
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#define HTMaxStrategyNumber 1
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/*
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* When a new operator class is declared, we require that the user supply
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* us with an amproc procudure for hashing a key of the new type.
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* Since we only have one such proc in amproc, it's number 1.
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*/
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#define HASHPROC 1
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/* public routines */
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extern Datum hashbuild(PG_FUNCTION_ARGS);
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extern Datum hashbuildempty(PG_FUNCTION_ARGS);
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extern Datum hashinsert(PG_FUNCTION_ARGS);
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extern Datum hashbeginscan(PG_FUNCTION_ARGS);
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extern Datum hashgettuple(PG_FUNCTION_ARGS);
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extern Datum hashgetbitmap(PG_FUNCTION_ARGS);
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extern Datum hashrescan(PG_FUNCTION_ARGS);
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extern Datum hashendscan(PG_FUNCTION_ARGS);
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extern Datum hashmarkpos(PG_FUNCTION_ARGS);
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extern Datum hashrestrpos(PG_FUNCTION_ARGS);
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extern Datum hashbulkdelete(PG_FUNCTION_ARGS);
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extern Datum hashvacuumcleanup(PG_FUNCTION_ARGS);
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extern Datum hashoptions(PG_FUNCTION_ARGS);
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/*
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* Datatype-specific hash functions in hashfunc.c.
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*
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* These support both hash indexes and hash joins.
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*
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* NOTE: some of these are also used by catcache operations, without
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* any direct connection to hash indexes. Also, the common hash_any
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* routine is also used by dynahash tables.
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*/
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extern Datum hashchar(PG_FUNCTION_ARGS);
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extern Datum hashint2(PG_FUNCTION_ARGS);
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extern Datum hashint4(PG_FUNCTION_ARGS);
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extern Datum hashint8(PG_FUNCTION_ARGS);
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extern Datum hashoid(PG_FUNCTION_ARGS);
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extern Datum hashenum(PG_FUNCTION_ARGS);
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extern Datum hashfloat4(PG_FUNCTION_ARGS);
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extern Datum hashfloat8(PG_FUNCTION_ARGS);
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extern Datum hashoidvector(PG_FUNCTION_ARGS);
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extern Datum hashint2vector(PG_FUNCTION_ARGS);
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extern Datum hashname(PG_FUNCTION_ARGS);
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extern Datum hashtext(PG_FUNCTION_ARGS);
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extern Datum hashvarlena(PG_FUNCTION_ARGS);
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extern Datum hash_any(register const unsigned char *k, register int keylen);
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extern Datum hash_uint32(uint32 k);
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/* private routines */
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/* hashinsert.c */
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extern void _hash_doinsert(Relation rel, IndexTuple itup);
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extern OffsetNumber _hash_pgaddtup(Relation rel, Buffer buf,
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Size itemsize, IndexTuple itup);
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/* hashovfl.c */
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extern Buffer _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf);
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extern BlockNumber _hash_freeovflpage(Relation rel, Buffer ovflbuf,
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BufferAccessStrategy bstrategy);
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extern void _hash_initbitmap(Relation rel, HashMetaPage metap,
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BlockNumber blkno, ForkNumber forkNum);
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extern void _hash_squeezebucket(Relation rel,
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Bucket bucket, BlockNumber bucket_blkno,
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BufferAccessStrategy bstrategy);
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/* hashpage.c */
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extern void _hash_getlock(Relation rel, BlockNumber whichlock, int access);
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extern bool _hash_try_getlock(Relation rel, BlockNumber whichlock, int access);
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extern void _hash_droplock(Relation rel, BlockNumber whichlock, int access);
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extern Buffer _hash_getbuf(Relation rel, BlockNumber blkno,
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int access, int flags);
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extern Buffer _hash_getinitbuf(Relation rel, BlockNumber blkno);
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extern Buffer _hash_getnewbuf(Relation rel, BlockNumber blkno,
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ForkNumber forkNum);
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extern Buffer _hash_getbuf_with_strategy(Relation rel, BlockNumber blkno,
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int access, int flags,
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BufferAccessStrategy bstrategy);
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extern void _hash_relbuf(Relation rel, Buffer buf);
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extern void _hash_dropbuf(Relation rel, Buffer buf);
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extern void _hash_wrtbuf(Relation rel, Buffer buf);
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extern void _hash_chgbufaccess(Relation rel, Buffer buf, int from_access,
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int to_access);
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extern uint32 _hash_metapinit(Relation rel, double num_tuples,
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ForkNumber forkNum);
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extern void _hash_pageinit(Page page, Size size);
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extern void _hash_expandtable(Relation rel, Buffer metabuf);
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/* hashscan.c */
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extern void _hash_regscan(IndexScanDesc scan);
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extern void _hash_dropscan(IndexScanDesc scan);
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extern bool _hash_has_active_scan(Relation rel, Bucket bucket);
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extern void ReleaseResources_hash(void);
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/* hashsearch.c */
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extern bool _hash_next(IndexScanDesc scan, ScanDirection dir);
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extern bool _hash_first(IndexScanDesc scan, ScanDirection dir);
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extern bool _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir);
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/* hashsort.c */
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typedef struct HSpool HSpool; /* opaque struct in hashsort.c */
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extern HSpool *_h_spoolinit(Relation index, uint32 num_buckets);
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extern void _h_spooldestroy(HSpool *hspool);
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extern void _h_spool(IndexTuple itup, HSpool *hspool);
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extern void _h_indexbuild(HSpool *hspool);
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/* hashutil.c */
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extern bool _hash_checkqual(IndexScanDesc scan, IndexTuple itup);
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extern uint32 _hash_datum2hashkey(Relation rel, Datum key);
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extern uint32 _hash_datum2hashkey_type(Relation rel, Datum key, Oid keytype);
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extern Bucket _hash_hashkey2bucket(uint32 hashkey, uint32 maxbucket,
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uint32 highmask, uint32 lowmask);
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extern uint32 _hash_log2(uint32 num);
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extern void _hash_checkpage(Relation rel, Buffer buf, int flags);
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extern uint32 _hash_get_indextuple_hashkey(IndexTuple itup);
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extern IndexTuple _hash_form_tuple(Relation index,
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Datum *values, bool *isnull);
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extern OffsetNumber _hash_binsearch(Page page, uint32 hash_value);
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extern OffsetNumber _hash_binsearch_last(Page page, uint32 hash_value);
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/* hash.c */
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extern void hash_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void hash_desc(StringInfo buf, uint8 xl_info, char *rec);
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#endif /* HASH_H */
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