heapam_xlog.h

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/*-------------------------------------------------------------------------
 *
 * heapam_xlog.h
 *    POSTGRES heap access XLOG definitions.
 *
 *
 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/access/heapam_xlog.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef HEAPAM_XLOG_H
#define HEAPAM_XLOG_H
 
#include "access/htup.h"
#include "access/xlogreader.h"
#include "lib/stringinfo.h"
#include "storage/buf.h"
#include "storage/bufpage.h"
#include "storage/relfilelocator.h"
#include "utils/relcache.h"
 
 
/*
 * WAL record definitions for heapam.c's WAL operations
 *
 * XLOG allows to store some information in high 4 bits of log
 * record xl_info field.  We use 3 for opcode and one for init bit.
 */
#define XLOG_HEAP_INSERT        0x00
#define XLOG_HEAP_DELETE        0x10
#define XLOG_HEAP_UPDATE        0x20
#define XLOG_HEAP_TRUNCATE      0x30
#define XLOG_HEAP_HOT_UPDATE    0x40
#define XLOG_HEAP_CONFIRM       0x50
#define XLOG_HEAP_LOCK          0x60
#define XLOG_HEAP_INPLACE       0x70
 
#define XLOG_HEAP_OPMASK        0x70
/*
 * When we insert 1st item on new page in INSERT, UPDATE, HOT_UPDATE,
 * or MULTI_INSERT, we can (and we do) restore entire page in redo
 */
#define XLOG_HEAP_INIT_PAGE     0x80
/*
 * We ran out of opcodes, so heapam.c now has a second RmgrId.  These opcodes
 * are associated with RM_HEAP2_ID, but are not logically different from
 * the ones above associated with RM_HEAP_ID.  XLOG_HEAP_OPMASK applies to
 * these, too.
 */
#define XLOG_HEAP2_REWRITE      0x00
#define XLOG_HEAP2_PRUNE        0x10
#define XLOG_HEAP2_VACUUM       0x20
#define XLOG_HEAP2_FREEZE_PAGE  0x30
#define XLOG_HEAP2_VISIBLE      0x40
#define XLOG_HEAP2_MULTI_INSERT 0x50
#define XLOG_HEAP2_LOCK_UPDATED 0x60
#define XLOG_HEAP2_NEW_CID      0x70
 
/*
 * xl_heap_insert/xl_heap_multi_insert flag values, 8 bits are available.
 */
/* PD_ALL_VISIBLE was cleared */
#define XLH_INSERT_ALL_VISIBLE_CLEARED          (1<<0)
#define XLH_INSERT_LAST_IN_MULTI                (1<<1)
#define XLH_INSERT_IS_SPECULATIVE               (1<<2)
#define XLH_INSERT_CONTAINS_NEW_TUPLE           (1<<3)
#define XLH_INSERT_ON_TOAST_RELATION            (1<<4)
 
/* all_frozen_set always implies all_visible_set */
#define XLH_INSERT_ALL_FROZEN_SET               (1<<5)
 
/*
 * xl_heap_update flag values, 8 bits are available.
 */
/* PD_ALL_VISIBLE was cleared */
#define XLH_UPDATE_OLD_ALL_VISIBLE_CLEARED      (1<<0)
/* PD_ALL_VISIBLE was cleared in the 2nd page */
#define XLH_UPDATE_NEW_ALL_VISIBLE_CLEARED      (1<<1)
#define XLH_UPDATE_CONTAINS_OLD_TUPLE           (1<<2)
#define XLH_UPDATE_CONTAINS_OLD_KEY             (1<<3)
#define XLH_UPDATE_CONTAINS_NEW_TUPLE           (1<<4)
#define XLH_UPDATE_PREFIX_FROM_OLD              (1<<5)
#define XLH_UPDATE_SUFFIX_FROM_OLD              (1<<6)
 
/* convenience macro for checking whether any form of old tuple was logged */
#define XLH_UPDATE_CONTAINS_OLD                     \
    (XLH_UPDATE_CONTAINS_OLD_TUPLE | XLH_UPDATE_CONTAINS_OLD_KEY)
 
/*
 * xl_heap_delete flag values, 8 bits are available.
 */
/* PD_ALL_VISIBLE was cleared */
#define XLH_DELETE_ALL_VISIBLE_CLEARED          (1<<0)
#define XLH_DELETE_CONTAINS_OLD_TUPLE           (1<<1)
#define XLH_DELETE_CONTAINS_OLD_KEY             (1<<2)
#define XLH_DELETE_IS_SUPER                     (1<<3)
#define XLH_DELETE_IS_PARTITION_MOVE            (1<<4)
 
/* convenience macro for checking whether any form of old tuple was logged */
#define XLH_DELETE_CONTAINS_OLD                     \
    (XLH_DELETE_CONTAINS_OLD_TUPLE | XLH_DELETE_CONTAINS_OLD_KEY)
 
/* This is what we need to know about delete */
typedef struct xl_heap_delete
{
    TransactionId xmax;         /* xmax of the deleted tuple */
    OffsetNumber offnum;        /* deleted tuple's offset */
    uint8       infobits_set;   /* infomask bits */
    uint8       flags;
} xl_heap_delete;
 
#define SizeOfHeapDelete    (offsetof(xl_heap_delete, flags) + sizeof(uint8))
 
/*
 * xl_heap_truncate flag values, 8 bits are available.
 */
#define XLH_TRUNCATE_CASCADE                    (1<<0)
#define XLH_TRUNCATE_RESTART_SEQS               (1<<1)
 
/*
 * For truncate we list all truncated relids in an array, followed by all
 * sequence relids that need to be restarted, if any.
 * All rels are always within the same database, so we just list dbid once.
 */
typedef struct xl_heap_truncate
{
    Oid         dbId;
    uint32      nrelids;
    uint8       flags;
    Oid         relids[FLEXIBLE_ARRAY_MEMBER];
} xl_heap_truncate;
 
#define SizeOfHeapTruncate  (offsetof(xl_heap_truncate, relids))
 
/*
 * We don't store the whole fixed part (HeapTupleHeaderData) of an inserted
 * or updated tuple in WAL; we can save a few bytes by reconstructing the
 * fields that are available elsewhere in the WAL record, or perhaps just
 * plain needn't be reconstructed.  These are the fields we must store.
 */
typedef struct xl_heap_header
{
    uint16      t_infomask2;
    uint16      t_infomask;
    uint8       t_hoff;
} xl_heap_header;
 
#define SizeOfHeapHeader    (offsetof(xl_heap_header, t_hoff) + sizeof(uint8))
 
/* This is what we need to know about insert */
typedef struct xl_heap_insert
{
    OffsetNumber offnum;        /* inserted tuple's offset */
    uint8       flags;
 
    /* xl_heap_header & TUPLE DATA in backup block 0 */
} xl_heap_insert;
 
#define SizeOfHeapInsert    (offsetof(xl_heap_insert, flags) + sizeof(uint8))
 
/*
 * This is what we need to know about a multi-insert.
 *
 * The main data of the record consists of this xl_heap_multi_insert header.
 * 'offsets' array is omitted if the whole page is reinitialized
 * (XLOG_HEAP_INIT_PAGE).
 *
 * In block 0's data portion, there is an xl_multi_insert_tuple struct,
 * followed by the tuple data for each tuple. There is padding to align
 * each xl_multi_insert_tuple struct.
 */
typedef struct xl_heap_multi_insert
{
    uint8       flags;
    uint16      ntuples;
    OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
} xl_heap_multi_insert;
 
#define SizeOfHeapMultiInsert   offsetof(xl_heap_multi_insert, offsets)
 
typedef struct xl_multi_insert_tuple
{
    uint16      datalen;        /* size of tuple data that follows */
    uint16      t_infomask2;
    uint16      t_infomask;
    uint8       t_hoff;
    /* TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_multi_insert_tuple;
 
#define SizeOfMultiInsertTuple  (offsetof(xl_multi_insert_tuple, t_hoff) + sizeof(uint8))
 
/*
 * This is what we need to know about update|hot_update
 *
 * Backup blk 0: new page
 *
 * If XLH_UPDATE_PREFIX_FROM_OLD or XLH_UPDATE_SUFFIX_FROM_OLD flags are set,
 * the prefix and/or suffix come first, as one or two uint16s.
 *
 * After that, xl_heap_header and new tuple data follow.  The new tuple
 * data doesn't include the prefix and suffix, which are copied from the
 * old tuple on replay.
 *
 * If XLH_UPDATE_CONTAINS_NEW_TUPLE flag is given, the tuple data is
 * included even if a full-page image was taken.
 *
 * Backup blk 1: old page, if different. (no data, just a reference to the blk)
 */
typedef struct xl_heap_update
{
    TransactionId old_xmax;     /* xmax of the old tuple */
    OffsetNumber old_offnum;    /* old tuple's offset */
    uint8       old_infobits_set;   /* infomask bits to set on old tuple */
    uint8       flags;
    TransactionId new_xmax;     /* xmax of the new tuple */
    OffsetNumber new_offnum;    /* new tuple's offset */
 
    /*
     * If XLH_UPDATE_CONTAINS_OLD_TUPLE or XLH_UPDATE_CONTAINS_OLD_KEY flags
     * are set, xl_heap_header and tuple data for the old tuple follow.
     */
} xl_heap_update;
 
#define SizeOfHeapUpdate    (offsetof(xl_heap_update, new_offnum) + sizeof(OffsetNumber))
 
/*
 * This is what we need to know about page pruning (both during VACUUM and
 * during opportunistic pruning)
 *
 * The array of OffsetNumbers following the fixed part of the record contains:
 *  * for each redirected item: the item offset, then the offset redirected to
 *  * for each now-dead item: the item offset
 *  * for each now-unused item: the item offset
 * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
 * Note that nunused is not explicitly stored, but may be found by reference
 * to the total record length.
 *
 * Acquires a full cleanup lock.
 */
typedef struct xl_heap_prune
{
    TransactionId snapshotConflictHorizon;
    uint16      nredirected;
    uint16      ndead;
    /* OFFSET NUMBERS are in the block reference 0 */
} xl_heap_prune;
 
#define SizeOfHeapPrune (offsetof(xl_heap_prune, ndead) + sizeof(uint16))
 
/*
 * The vacuum page record is similar to the prune record, but can only mark
 * already LP_DEAD items LP_UNUSED (during VACUUM's second heap pass)
 *
 * Acquires an ordinary exclusive lock only.
 */
typedef struct xl_heap_vacuum
{
    uint16      nunused;
    /* OFFSET NUMBERS are in the block reference 0 */
} xl_heap_vacuum;
 
#define SizeOfHeapVacuum (offsetof(xl_heap_vacuum, nunused) + sizeof(uint16))
 
/* flags for infobits_set */
#define XLHL_XMAX_IS_MULTI      0x01
#define XLHL_XMAX_LOCK_ONLY     0x02
#define XLHL_XMAX_EXCL_LOCK     0x04
#define XLHL_XMAX_KEYSHR_LOCK   0x08
#define XLHL_KEYS_UPDATED       0x10
 
/* flag bits for xl_heap_lock / xl_heap_lock_updated's flag field */
#define XLH_LOCK_ALL_FROZEN_CLEARED     0x01
 
/* This is what we need to know about lock */
typedef struct xl_heap_lock
{
    TransactionId locking_xid;  /* might be a MultiXactId not xid */
    OffsetNumber offnum;        /* locked tuple's offset on page */
    int8        infobits_set;   /* infomask and infomask2 bits to set */
    uint8       flags;          /* XLH_LOCK_* flag bits */
} xl_heap_lock;
 
#define SizeOfHeapLock  (offsetof(xl_heap_lock, flags) + sizeof(int8))
 
/* This is what we need to know about locking an updated version of a row */
typedef struct xl_heap_lock_updated
{
    TransactionId xmax;
    OffsetNumber offnum;
    uint8       infobits_set;
    uint8       flags;
} xl_heap_lock_updated;
 
#define SizeOfHeapLockUpdated   (offsetof(xl_heap_lock_updated, flags) + sizeof(uint8))
 
/* This is what we need to know about confirmation of speculative insertion */
typedef struct xl_heap_confirm
{
    OffsetNumber offnum;        /* confirmed tuple's offset on page */
} xl_heap_confirm;
 
#define SizeOfHeapConfirm   (offsetof(xl_heap_confirm, offnum) + sizeof(OffsetNumber))
 
/* This is what we need to know about in-place update */
typedef struct xl_heap_inplace
{
    OffsetNumber offnum;        /* updated tuple's offset on page */
    /* TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_heap_inplace;
 
#define SizeOfHeapInplace   (offsetof(xl_heap_inplace, offnum) + sizeof(OffsetNumber))
 
/*
 * This struct represents a 'freeze plan', which describes how to freeze a
 * group of one or more heap tuples (appears in xl_heap_freeze_page record)
 */
/* 0x01 was XLH_FREEZE_XMIN */
#define     XLH_FREEZE_XVAC     0x02
#define     XLH_INVALID_XVAC    0x04
 
typedef struct xl_heap_freeze_plan
{
    TransactionId xmax;
    uint16      t_infomask2;
    uint16      t_infomask;
    uint8       frzflags;
 
    /* Length of individual page offset numbers array for this plan */
    uint16      ntuples;
} xl_heap_freeze_plan;
 
/*
 * This is what we need to know about a block being frozen during vacuum
 *
 * Backup block 0's data contains an array of xl_heap_freeze_plan structs
 * (with nplans elements), followed by one or more page offset number arrays.
 * Each such page offset number array corresponds to a single freeze plan
 * (REDO routine freezes corresponding heap tuples using freeze plan).
 */
typedef struct xl_heap_freeze_page
{
    TransactionId snapshotConflictHorizon;
    uint16      nplans;
 
    /*
     * In payload of blk 0 : FREEZE PLANS and OFFSET NUMBER ARRAY
     */
} xl_heap_freeze_page;
 
#define SizeOfHeapFreezePage (offsetof(xl_heap_freeze_page, nplans) + sizeof(uint16))
 
/*
 * This is what we need to know about setting a visibility map bit
 *
 * Backup blk 0: visibility map buffer
 * Backup blk 1: heap buffer
 */
typedef struct xl_heap_visible
{
    TransactionId snapshotConflictHorizon;
    uint8       flags;
} xl_heap_visible;
 
#define SizeOfHeapVisible (offsetof(xl_heap_visible, flags) + sizeof(uint8))
 
typedef struct xl_heap_new_cid
{
    /*
     * store toplevel xid so we don't have to merge cids from different
     * transactions
     */
    TransactionId top_xid;
    CommandId   cmin;
    CommandId   cmax;
    CommandId   combocid;       /* just for debugging */
 
    /*
     * Store the relfilelocator/ctid pair to facilitate lookups.
     */
    RelFileLocator target_locator;
    ItemPointerData target_tid;
} xl_heap_new_cid;
 
#define SizeOfHeapNewCid (offsetof(xl_heap_new_cid, target_tid) + sizeof(ItemPointerData))
 
/* logical rewrite xlog record header */
typedef struct xl_heap_rewrite_mapping
{
    TransactionId mapped_xid;   /* xid that might need to see the row */
    Oid         mapped_db;      /* DbOid or InvalidOid for shared rels */
    Oid         mapped_rel;     /* Oid of the mapped relation */
    off_t       offset;         /* How far have we written so far */
    uint32      num_mappings;   /* Number of in-memory mappings */
    XLogRecPtr  start_lsn;      /* Insert LSN at begin of rewrite */
} xl_heap_rewrite_mapping;
 
extern void HeapTupleHeaderAdvanceConflictHorizon(HeapTupleHeader tuple,
                                                  TransactionId *snapshotConflictHorizon);
 
extern void heap_redo(XLogReaderState *record);
extern void heap_desc(StringInfo buf, XLogReaderState *record);
extern const char *heap_identify(uint8 info);
extern void heap_mask(char *pagedata, BlockNumber blkno);
extern void heap2_redo(XLogReaderState *record);
extern void heap2_desc(StringInfo buf, XLogReaderState *record);
extern const char *heap2_identify(uint8 info);
extern void heap_xlog_logical_rewrite(XLogReaderState *r);
 
extern XLogRecPtr log_heap_visible(RelFileLocator rlocator, Buffer heap_buffer,
                                   Buffer vm_buffer,
                                   TransactionId snapshotConflictHorizon,
                                   uint8 vmflags);
 
#endif                          /* HEAPAM_XLOG_H */