diff options
Diffstat (limited to 'src/include/access/hash.h')
| -rw-r--r-- | src/include/access/hash.h | 55 |
1 files changed, 29 insertions, 26 deletions
diff --git a/src/include/access/hash.h b/src/include/access/hash.h index 045fb40c40a..7edbdad0984 100644 --- a/src/include/access/hash.h +++ b/src/include/access/hash.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: hash.h,v 1.51 2003/09/02 02:18:38 tgl Exp $ + * $Id: hash.h,v 1.52 2003/09/02 18:13:32 tgl Exp $ * * NOTES * modeled after Margo Seltzer's hash implementation for unix. @@ -51,15 +51,24 @@ typedef uint32 Bucket; typedef struct HashPageOpaqueData { - bits16 hasho_flag; /* page type code, see above */ - Bucket hasho_bucket; /* bucket number this pg belongs to */ - bits16 hasho_oaddr; /* no longer used; delete someday */ - BlockNumber hasho_nextblkno; /* next ovfl blkno */ BlockNumber hasho_prevblkno; /* previous ovfl (or bucket) blkno */ + BlockNumber hasho_nextblkno; /* next ovfl blkno */ + Bucket hasho_bucket; /* bucket number this pg belongs to */ + uint16 hasho_flag; /* page type code, see above */ + uint16 hasho_filler; /* available for future use */ + /* + * We presently set hasho_filler to HASHO_FILL (0x1234); this is for + * the convenience of pg_filedump, which otherwise would have a hard + * time telling HashPageOpaqueData from BTPageOpaqueData. If we ever + * need that space for some other purpose, pg_filedump will have to + * find another way. + */ } HashPageOpaqueData; typedef HashPageOpaqueData *HashPageOpaque; +#define HASHO_FILL 0x1234 + /* * ScanOpaqueData is used to remember which buffers we're currently * examining in the scan. We keep these buffers locked and pinned and @@ -81,7 +90,7 @@ typedef HashScanOpaqueData *HashScanOpaque; #define HASH_METAPAGE 0 /* metapage is always block 0 */ #define HASH_MAGIC 0x6440640 -#define HASH_VERSION 0 +#define HASH_VERSION 1 /* new for Pg 7.4 */ /* * Spares[] holds the number of overflow pages currently allocated at or @@ -99,25 +108,24 @@ typedef HashScanOpaqueData *HashScanOpaque; * * The limitation on the size of spares[] comes from the fact that there's * no point in having more than 2^32 buckets with only uint32 hashcodes. - * There is no particularly good reason for bitmaps[] to be the same size, - * but we're stuck with that until we want to force an initdb. (With 8K - * block size, 32 bitmaps limit us to 8 Gb of overflow space...) + * There is no particular upper limit on the size of mapp[], other than + * needing to fit into the metapage. (With 8K block size, 128 bitmaps + * limit us to 64 Gb of overflow space...) */ #define HASH_MAX_SPLITPOINTS 32 -#define HASH_MAX_BITMAPS 32 +#define HASH_MAX_BITMAPS 128 typedef struct HashMetaPageData { PageHeaderData hashm_phdr; /* pad for page header (do not use) */ uint32 hashm_magic; /* magic no. for hash tables */ uint32 hashm_version; /* version ID */ - uint32 hashm_ntuples; /* number of tuples stored in the table */ + double hashm_ntuples; /* number of tuples stored in the table */ uint16 hashm_ffactor; /* target fill factor (tuples/bucket) */ - uint16 hashm_bsize; /* index page size (bytes) - must be a power - * of 2 */ - uint16 hashm_bshift; /* log2(bsize) */ - uint16 hashm_bmsize; /* bitmap array size (bytes) - must be - * exactly half of hashm_bsize */ + uint16 hashm_bsize; /* index page size (bytes) */ + uint16 hashm_bmsize; /* bitmap array size (bytes) - must be a + * power of 2 */ + uint16 hashm_bmshift; /* log2(bitmap array size in BITS) */ uint32 hashm_maxbucket; /* ID of maximum bucket in use */ uint32 hashm_highmask; /* mask to modulo into entire table */ uint32 hashm_lowmask; /* mask to modulo into lower half of table */ @@ -125,10 +133,10 @@ typedef struct HashMetaPageData * allocated */ uint32 hashm_firstfree; /* lowest-number free ovflpage (bit#) */ uint32 hashm_nmaps; /* number of bitmap pages */ + RegProcedure hashm_procid; /* hash procedure id from pg_proc */ uint32 hashm_spares[HASH_MAX_SPLITPOINTS]; /* spare pages before * each splitpoint */ BlockNumber hashm_mapp[HASH_MAX_BITMAPS]; /* blknos of ovfl bitmaps */ - RegProcedure hashm_procid; /* hash procedure id from pg_proc */ } HashMetaPageData; typedef HashMetaPageData *HashMetaPage; @@ -151,16 +159,12 @@ typedef HashItemData *HashItem; * Bitmap pages do not contain tuples. They do contain the standard * page headers and trailers; however, everything in between is a * giant bit array. The number of bits that fit on a page obviously - * depends on the page size and the header/trailer overhead. In the - * present implementation, we use exactly half of a page for bitmap, - * so that we have a power-of-2 bits per page. - * - * The fact that the metapage has separate bsize and bmsize fields, - * but only one bshift field, is a design error that ought to be fixed. + * depends on the page size and the header/trailer overhead. We require + * the number of bits per page to be a power of 2. */ #define BMPGSZ_BYTE(metap) ((metap)->hashm_bmsize) #define BMPGSZ_BIT(metap) ((metap)->hashm_bmsize << BYTE_TO_BIT) -#define BMPG_SHIFT(metap) ((metap)->hashm_bshift - 1 + BYTE_TO_BIT) +#define BMPG_SHIFT(metap) ((metap)->hashm_bmshift) #define BMPG_MASK(metap) (BMPGSZ_BIT(metap) - 1) #define HashPageGetBitmap(pg) \ ((uint32 *) (((char *) (pg)) + MAXALIGN(sizeof(PageHeaderData)))) @@ -254,7 +258,6 @@ extern void _hash_wrtnorelbuf(Buffer buf); extern void _hash_chgbufaccess(Relation rel, Buffer buf, int from_access, int to_access); extern void _hash_pageinit(Page page, Size size); -extern void _hash_pagedel(Relation rel, ItemPointer tid); extern void _hash_expandtable(Relation rel, Buffer metabuf); /* hashscan.c */ @@ -278,7 +281,7 @@ extern bool _hash_checkqual(IndexScanDesc scan, IndexTuple itup); extern HashItem _hash_formitem(IndexTuple itup); extern Bucket _hash_call(Relation rel, HashMetaPage metap, Datum key); extern uint32 _hash_log2(uint32 num); -extern void _hash_checkpage(Page page, int flags); +extern void _hash_checkpage(Relation rel, Page page, int flags); /* hash.c */ extern void hash_redo(XLogRecPtr lsn, XLogRecord *record); |