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97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
/*
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* brin_page.h
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* Prototypes and definitions for BRIN page layouts
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*
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* Portions Copyright (c) 1996-2025, 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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* IDENTIFICATION
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* src/include/access/brin_page.h
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*
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* NOTES
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*
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* These structs should really be private to specific BRIN files, but it's
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* useful to have them here so that they can be used by pageinspect and similar
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* tools.
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*/
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#ifndef BRIN_PAGE_H
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#define BRIN_PAGE_H
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#include "storage/block.h"
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#include "storage/itemptr.h"
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/*
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* Special area of BRIN pages.
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*
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* We define it in this odd way so that it always occupies the last
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* MAXALIGN-sized element of each page.
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*/
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typedef struct BrinSpecialSpace
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{
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uint16 vector[MAXALIGN(1) / sizeof(uint16)];
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} BrinSpecialSpace;
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/*
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* Make the page type be the last half-word in the page, for consumption by
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* pg_filedump and similar utilities. We don't really care much about the
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* position of the "flags" half-word, but it's simpler to apply a consistent
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* rule to both.
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*
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* See comments above GinPageOpaqueData.
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*/
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#define BrinPageType(page) \
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(((BrinSpecialSpace *) \
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PageGetSpecialPointer(page))->vector[MAXALIGN(1) / sizeof(uint16) - 1])
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#define BrinPageFlags(page) \
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(((BrinSpecialSpace *) \
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PageGetSpecialPointer(page))->vector[MAXALIGN(1) / sizeof(uint16) - 2])
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/* special space on all BRIN pages stores a "type" identifier */
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#define BRIN_PAGETYPE_META 0xF091
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#define BRIN_PAGETYPE_REVMAP 0xF092
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#define BRIN_PAGETYPE_REGULAR 0xF093
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#define BRIN_IS_META_PAGE(page) (BrinPageType(page) == BRIN_PAGETYPE_META)
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#define BRIN_IS_REVMAP_PAGE(page) (BrinPageType(page) == BRIN_PAGETYPE_REVMAP)
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#define BRIN_IS_REGULAR_PAGE(page) (BrinPageType(page) == BRIN_PAGETYPE_REGULAR)
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/* flags for BrinSpecialSpace */
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#define BRIN_EVACUATE_PAGE (1 << 0)
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/* Metapage definitions */
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typedef struct BrinMetaPageData
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{
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uint32 brinMagic;
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uint32 brinVersion;
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BlockNumber pagesPerRange;
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BlockNumber lastRevmapPage;
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} BrinMetaPageData;
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#define BRIN_CURRENT_VERSION 1
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#define BRIN_META_MAGIC 0xA8109CFA
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#define BRIN_METAPAGE_BLKNO 0
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/* Definitions for revmap pages */
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typedef struct RevmapContents
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{
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/*
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* This array will fill all available space on the page. It should be
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* declared [FLEXIBLE_ARRAY_MEMBER], but for some reason you can't do that
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* in an otherwise-empty struct.
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*/
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ItemPointerData rm_tids[1];
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} RevmapContents;
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#define REVMAP_CONTENT_SIZE \
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(BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - \
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offsetof(RevmapContents, rm_tids) - \
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MAXALIGN(sizeof(BrinSpecialSpace)))
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/* max num of items in the array */
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#define REVMAP_PAGE_MAXITEMS \
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(REVMAP_CONTENT_SIZE / sizeof(ItemPointerData))
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#endif /* BRIN_PAGE_H */
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