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/*
* brin_page.h
* Prototypes and definitions for BRIN page layouts
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/include/access/brin_page.h
*
* NOTES
*
* These structs should really be private to specific BRIN files, but it's
* useful to have them here so that they can be used by pageinspect and similar
* tools.
*/
#ifndef BRIN_PAGE_H
#define BRIN_PAGE_H
#include "storage/block.h"
#include "storage/itemptr.h"
/*
* Special area of BRIN pages.
*
* We define it in this odd way so that it always occupies the last
* MAXALIGN-sized element of each page.
*/
typedef struct BrinSpecialSpace
{
uint16 vector[MAXALIGN(1) / sizeof(uint16)];
} BrinSpecialSpace;
/*
* Make the page type be the last half-word in the page, for consumption by
* pg_filedump and similar utilities. We don't really care much about the
* position of the "flags" half-word, but it's simpler to apply a consistent
* rule to both.
*
* See comments above GinPageOpaqueData.
*/
#define BrinPageType(page) \
(((BrinSpecialSpace *) \
PageGetSpecialPointer(page))->vector[MAXALIGN(1) / sizeof(uint16) - 1])
#define BrinPageFlags(page) \
(((BrinSpecialSpace *) \
PageGetSpecialPointer(page))->vector[MAXALIGN(1) / sizeof(uint16) - 2])
/* special space on all BRIN pages stores a "type" identifier */
#define BRIN_PAGETYPE_META 0xF091
#define BRIN_PAGETYPE_REVMAP 0xF092
#define BRIN_PAGETYPE_REGULAR 0xF093
#define BRIN_IS_META_PAGE(page) (BrinPageType(page) == BRIN_PAGETYPE_META)
#define BRIN_IS_REVMAP_PAGE(page) (BrinPageType(page) == BRIN_PAGETYPE_REVMAP)
#define BRIN_IS_REGULAR_PAGE(page) (BrinPageType(page) == BRIN_PAGETYPE_REGULAR)
/* flags for BrinSpecialSpace */
#define BRIN_EVACUATE_PAGE (1 << 0)
/* Metapage definitions */
typedef struct BrinMetaPageData
{
uint32 brinMagic;
uint32 brinVersion;
BlockNumber pagesPerRange;
BlockNumber lastRevmapPage;
} BrinMetaPageData;
#define BRIN_CURRENT_VERSION 1
#define BRIN_META_MAGIC 0xA8109CFA
#define BRIN_METAPAGE_BLKNO 0
/* Definitions for revmap pages */
typedef struct RevmapContents
{
/*
* This array will fill all available space on the page. It should be
* declared [FLEXIBLE_ARRAY_MEMBER], but for some reason you can't do that
* in an otherwise-empty struct.
*/
ItemPointerData rm_tids[1];
} RevmapContents;
#define REVMAP_CONTENT_SIZE \
(BLCKSZ - MAXALIGN(SizeOfPageHeaderData) - \
offsetof(RevmapContents, rm_tids) - \
MAXALIGN(sizeof(BrinSpecialSpace)))
/* max num of items in the array */
#define REVMAP_PAGE_MAXITEMS \
(REVMAP_CONTENT_SIZE / sizeof(ItemPointerData))
#endif /* BRIN_PAGE_H */
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