hash_xlog.h

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/*-------------------------------------------------------------------------
 *
 * hash_xlog.h
 *    header file for Postgres hash AM implementation
 *
 *
 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/access/hash_xlog.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef HASH_XLOG_H
#define HASH_XLOG_H
 
#include "access/xlogreader.h"
#include "lib/stringinfo.h"
#include "storage/off.h"
 
/* Number of buffers required for XLOG_HASH_SQUEEZE_PAGE operation */
#define HASH_XLOG_FREE_OVFL_BUFS    6
 
/*
 * XLOG records for hash operations
 */
#define XLOG_HASH_INIT_META_PAGE    0x00    /* initialize the meta page */
#define XLOG_HASH_INIT_BITMAP_PAGE  0x10    /* initialize the bitmap page */
#define XLOG_HASH_INSERT        0x20    /* add index tuple without split */
#define XLOG_HASH_ADD_OVFL_PAGE 0x30    /* add overflow page */
#define XLOG_HASH_SPLIT_ALLOCATE_PAGE   0x40    /* allocate new page for split */
#define XLOG_HASH_SPLIT_PAGE    0x50    /* split page */
#define XLOG_HASH_SPLIT_COMPLETE    0x60    /* completion of split operation */
#define XLOG_HASH_MOVE_PAGE_CONTENTS    0x70    /* remove tuples from one page
                                                 * and add to another page */
#define XLOG_HASH_SQUEEZE_PAGE  0x80    /* add tuples to one of the previous
                                         * pages in chain and free the ovfl
                                         * page */
#define XLOG_HASH_DELETE        0x90    /* delete index tuples from a page */
#define XLOG_HASH_SPLIT_CLEANUP 0xA0    /* clear split-cleanup flag in primary
                                         * bucket page after deleting tuples
                                         * that are moved due to split  */
#define XLOG_HASH_UPDATE_META_PAGE  0xB0    /* update meta page after vacuum */
 
#define XLOG_HASH_VACUUM_ONE_PAGE   0xC0    /* remove dead tuples from index
                                             * page */
 
/*
 * xl_hash_split_allocate_page flag values, 8 bits are available.
 */
#define XLH_SPLIT_META_UPDATE_MASKS     (1<<0)
#define XLH_SPLIT_META_UPDATE_SPLITPOINT        (1<<1)
 
/*
 * This is what we need to know about simple (without split) insert.
 *
 * This data record is used for XLOG_HASH_INSERT
 *
 * Backup Blk 0: original page (data contains the inserted tuple)
 * Backup Blk 1: metapage (HashMetaPageData)
 */
typedef struct xl_hash_insert
{
    OffsetNumber offnum;
} xl_hash_insert;
 
#define SizeOfHashInsert    (offsetof(xl_hash_insert, offnum) + sizeof(OffsetNumber))
 
/*
 * This is what we need to know about addition of overflow page.
 *
 * This data record is used for XLOG_HASH_ADD_OVFL_PAGE
 *
 * Backup Blk 0: newly allocated overflow page
 * Backup Blk 1: page before new overflow page in the bucket chain
 * Backup Blk 2: bitmap page
 * Backup Blk 3: new bitmap page
 * Backup Blk 4: metapage
 */
typedef struct xl_hash_add_ovfl_page
{
    uint16      bmsize;
    bool        bmpage_found;
} xl_hash_add_ovfl_page;
 
#define SizeOfHashAddOvflPage   \
    (offsetof(xl_hash_add_ovfl_page, bmpage_found) + sizeof(bool))
 
/*
 * This is what we need to know about allocating a page for split.
 *
 * This data record is used for XLOG_HASH_SPLIT_ALLOCATE_PAGE
 *
 * Backup Blk 0: page for old bucket
 * Backup Blk 1: page for new bucket
 * Backup Blk 2: metapage
 */
typedef struct xl_hash_split_allocate_page
{
    uint32      new_bucket;
    uint16      old_bucket_flag;
    uint16      new_bucket_flag;
    uint8       flags;
} xl_hash_split_allocate_page;
 
#define SizeOfHashSplitAllocPage    \
    (offsetof(xl_hash_split_allocate_page, flags) + sizeof(uint8))
 
/*
 * This is what we need to know about completing the split operation.
 *
 * This data record is used for XLOG_HASH_SPLIT_COMPLETE
 *
 * Backup Blk 0: page for old bucket
 * Backup Blk 1: page for new bucket
 */
typedef struct xl_hash_split_complete
{
    uint16      old_bucket_flag;
    uint16      new_bucket_flag;
} xl_hash_split_complete;
 
#define SizeOfHashSplitComplete \
    (offsetof(xl_hash_split_complete, new_bucket_flag) + sizeof(uint16))
 
/*
 * This is what we need to know about move page contents required during
 * squeeze operation.
 *
 * This data record is used for XLOG_HASH_MOVE_PAGE_CONTENTS
 *
 * Backup Blk 0: primary bucket page
 * Backup Blk 1: page containing moved tuples
 * Backup Blk 2: page from which tuples will be removed
 */
typedef struct xl_hash_move_page_contents
{
    uint16      ntups;
    bool        is_prim_bucket_same_wrt;    /* true if the page to which
                                             * tuples are moved is same as
                                             * primary bucket page */
} xl_hash_move_page_contents;
 
#define SizeOfHashMovePageContents  \
    (offsetof(xl_hash_move_page_contents, is_prim_bucket_same_wrt) + sizeof(bool))
 
/*
 * This is what we need to know about the squeeze page operation.
 *
 * This data record is used for XLOG_HASH_SQUEEZE_PAGE
 *
 * Backup Blk 0: primary bucket page
 * Backup Blk 1: page containing tuples moved from freed overflow page
 * Backup Blk 2: freed overflow page
 * Backup Blk 3: page previous to the freed overflow page
 * Backup Blk 4: page next to the freed overflow page
 * Backup Blk 5: bitmap page containing info of freed overflow page
 * Backup Blk 6: meta page
 */
typedef struct xl_hash_squeeze_page
{
    BlockNumber prevblkno;
    BlockNumber nextblkno;
    uint16      ntups;
    bool        is_prim_bucket_same_wrt;    /* true if the page to which
                                             * tuples are moved is same as
                                             * primary bucket page */
    bool        is_prev_bucket_same_wrt;    /* true if the page to which
                                             * tuples are moved is the page
                                             * previous to the freed overflow
                                             * page */
} xl_hash_squeeze_page;
 
#define SizeOfHashSqueezePage   \
    (offsetof(xl_hash_squeeze_page, is_prev_bucket_same_wrt) + sizeof(bool))
 
/*
 * This is what we need to know about the deletion of index tuples from a page.
 *
 * This data record is used for XLOG_HASH_DELETE
 *
 * Backup Blk 0: primary bucket page
 * Backup Blk 1: page from which tuples are deleted
 */
typedef struct xl_hash_delete
{
    bool        clear_dead_marking; /* true if this operation clears
                                     * LH_PAGE_HAS_DEAD_TUPLES flag */
    bool        is_primary_bucket_page; /* true if the operation is for
                                         * primary bucket page */
} xl_hash_delete;
 
#define SizeOfHashDelete    (offsetof(xl_hash_delete, is_primary_bucket_page) + sizeof(bool))
 
/*
 * This is what we need for metapage update operation.
 *
 * This data record is used for XLOG_HASH_UPDATE_META_PAGE
 *
 * Backup Blk 0: meta page
 */
typedef struct xl_hash_update_meta_page
{
    double      ntuples;
} xl_hash_update_meta_page;
 
#define SizeOfHashUpdateMetaPage    \
    (offsetof(xl_hash_update_meta_page, ntuples) + sizeof(double))
 
/*
 * This is what we need to initialize metapage.
 *
 * This data record is used for XLOG_HASH_INIT_META_PAGE
 *
 * Backup Blk 0: meta page
 */
typedef struct xl_hash_init_meta_page
{
    double      num_tuples;
    RegProcedure procid;
    uint16      ffactor;
} xl_hash_init_meta_page;
 
#define SizeOfHashInitMetaPage      \
    (offsetof(xl_hash_init_meta_page, ffactor) + sizeof(uint16))
 
/*
 * This is what we need to initialize bitmap page.
 *
 * This data record is used for XLOG_HASH_INIT_BITMAP_PAGE
 *
 * Backup Blk 0: bitmap page
 * Backup Blk 1: meta page
 */
typedef struct xl_hash_init_bitmap_page
{
    uint16      bmsize;
} xl_hash_init_bitmap_page;
 
#define SizeOfHashInitBitmapPage    \
    (offsetof(xl_hash_init_bitmap_page, bmsize) + sizeof(uint16))
 
/*
 * This is what we need for index tuple deletion and to
 * update the meta page.
 *
 * This data record is used for XLOG_HASH_VACUUM_ONE_PAGE
 *
 * Backup Blk 0: primary bucket page
 * Backup Blk 1: meta page
 */
typedef struct xl_hash_vacuum_one_page
{
    TransactionId snapshotConflictHorizon;
    uint16      ntuples;
    bool        isCatalogRel;   /* to handle recovery conflict during logical
                                 * decoding on standby */
 
    /* TARGET OFFSET NUMBERS */
    OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
} xl_hash_vacuum_one_page;
 
#define SizeOfHashVacuumOnePage offsetof(xl_hash_vacuum_one_page, offsets)
 
extern void hash_redo(XLogReaderState *record);
extern void hash_desc(StringInfo buf, XLogReaderState *record);
extern const char *hash_identify(uint8 info);
extern void hash_mask(char *pagedata, BlockNumber blkno);
 
#endif                          /* HASH_XLOG_H */