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postgresql/src/include/access/heapam.h
Tom Lane 282d2a03dd HOT updates. When we update a tuple without changing any of its indexed 
columns, and the new version can be stored on the same heap page, we no longer
generate extra index entries for the new version.  Instead, index searches
follow the HOT-chain links to ensure they find the correct tuple version.

In addition, this patch introduces the ability to "prune" dead tuples on a
per-page basis, without having to do a complete VACUUM pass to recover space.
VACUUM is still needed to clean up dead index entries, however.

Pavan Deolasee, with help from a bunch of other people.
2007-09-20 17:56:33 +00:00

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/*-------------------------------------------------------------------------
*
* heapam.h
* POSTGRES heap access method definitions.
*
*
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.127 2007/09/20 17:56:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef HEAPAM_H
#define HEAPAM_H
#include "access/htup.h"
#include "access/relscan.h"
#include "access/sdir.h"
#include "access/tupmacs.h"
#include "access/xlogutils.h"
#include "nodes/primnodes.h"
#include "storage/block.h"
#include "storage/lmgr.h"
#include "utils/rel.h"
#include "utils/tqual.h"
/* ----------------
* fastgetattr
*
* Fetch a user attribute's value as a Datum (might be either a
* value, or a pointer into the data area of the tuple).
*
* This must not be used when a system attribute might be requested.
* Furthermore, the passed attnum MUST be valid. Use heap_getattr()
* instead, if in doubt.
*
* This gets called many times, so we macro the cacheable and NULL
* lookups, and call nocachegetattr() for the rest.
* ----------------
*/
#if !defined(DISABLE_COMPLEX_MACRO)
#define fastgetattr(tup, attnum, tupleDesc, isnull) \
( \
AssertMacro((attnum) > 0), \
(((isnull) != NULL) ? (*(isnull) = false) : (dummyret)NULL), \
HeapTupleNoNulls(tup) ? \
( \
(tupleDesc)->attrs[(attnum)-1]->attcacheoff >= 0 ? \
( \
fetchatt((tupleDesc)->attrs[(attnum)-1], \
(char *) (tup)->t_data + (tup)->t_data->t_hoff + \
(tupleDesc)->attrs[(attnum)-1]->attcacheoff) \
) \
: \
nocachegetattr((tup), (attnum), (tupleDesc), (isnull)) \
) \
: \
( \
att_isnull((attnum)-1, (tup)->t_data->t_bits) ? \
( \
(((isnull) != NULL) ? (*(isnull) = true) : (dummyret)NULL), \
(Datum)NULL \
) \
: \
( \
nocachegetattr((tup), (attnum), (tupleDesc), (isnull)) \
) \
) \
)
#else /* defined(DISABLE_COMPLEX_MACRO) */
extern Datum fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
bool *isnull);
#endif /* defined(DISABLE_COMPLEX_MACRO) */
/* ----------------
* heap_getattr
*
* Extract an attribute of a heap tuple and return it as a Datum.
* This works for either system or user attributes. The given attnum
* is properly range-checked.
*
* If the field in question has a NULL value, we return a zero Datum
* and set *isnull == true. Otherwise, we set *isnull == false.
*
* <tup> is the pointer to the heap tuple. <attnum> is the attribute
* number of the column (field) caller wants. <tupleDesc> is a
* pointer to the structure describing the row and all its fields.
* ----------------
*/
#define heap_getattr(tup, attnum, tupleDesc, isnull) \
( \
AssertMacro((tup) != NULL), \
( \
((attnum) > 0) ? \
( \
((attnum) > (int) HeapTupleHeaderGetNatts((tup)->t_data)) ? \
( \
(((isnull) != NULL) ? (*(isnull) = true) : (dummyret)NULL), \
(Datum)NULL \
) \
: \
fastgetattr((tup), (attnum), (tupleDesc), (isnull)) \
) \
: \
heap_getsysattr((tup), (attnum), (tupleDesc), (isnull)) \
) \
)
typedef enum
{
LockTupleShared,
LockTupleExclusive
} LockTupleMode;
/* ----------------
* function prototypes for heap access method
*
* heap_create, heap_create_with_catalog, and heap_drop_with_catalog
* are declared in catalog/heap.h
* ----------------
*/
/* in heap/heapam.c */
extern Relation relation_open(Oid relationId, LOCKMODE lockmode);
extern Relation try_relation_open(Oid relationId, LOCKMODE lockmode);
extern Relation relation_open_nowait(Oid relationId, LOCKMODE lockmode);
extern Relation relation_openrv(const RangeVar *relation, LOCKMODE lockmode);
extern void relation_close(Relation relation, LOCKMODE lockmode);
extern Relation heap_open(Oid relationId, LOCKMODE lockmode);
extern Relation heap_openrv(const RangeVar *relation, LOCKMODE lockmode);
#define heap_close(r,l) relation_close(r,l)
extern HeapScanDesc heap_beginscan(Relation relation, Snapshot snapshot,
int nkeys, ScanKey key);
extern HeapScanDesc heap_beginscan_bm(Relation relation, Snapshot snapshot,
int nkeys, ScanKey key);
extern void heap_rescan(HeapScanDesc scan, ScanKey key);
extern void heap_endscan(HeapScanDesc scan);
extern HeapTuple heap_getnext(HeapScanDesc scan, ScanDirection direction);
extern bool heap_fetch(Relation relation, Snapshot snapshot,
HeapTuple tuple, Buffer *userbuf, bool keep_buf,
Relation stats_relation);
extern bool heap_release_fetch(Relation relation, Snapshot snapshot,
HeapTuple tuple, Buffer *userbuf, bool keep_buf,
Relation stats_relation);
extern bool heap_hot_search_buffer(ItemPointer tid, Buffer buffer,
Snapshot snapshot, bool *all_dead);
extern bool heap_hot_search(ItemPointer tid, Relation relation,
Snapshot snapshot, bool *all_dead);
extern void heap_get_latest_tid(Relation relation, Snapshot snapshot,
ItemPointer tid);
extern void setLastTid(const ItemPointer tid);
extern Oid heap_insert(Relation relation, HeapTuple tup, CommandId cid,
bool use_wal, bool use_fsm);
extern HTSU_Result heap_delete(Relation relation, ItemPointer tid,
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid, Snapshot crosscheck, bool wait);
extern HTSU_Result heap_update(Relation relation, ItemPointer otid,
HeapTuple newtup,
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid, Snapshot crosscheck, bool wait);
extern HTSU_Result heap_lock_tuple(Relation relation, HeapTuple tuple,
Buffer *buffer, ItemPointer ctid,
TransactionId *update_xmax, CommandId cid,
LockTupleMode mode, bool nowait);
extern void heap_inplace_update(Relation relation, HeapTuple tuple);
extern bool heap_freeze_tuple(HeapTupleHeader tuple, TransactionId cutoff_xid,
Buffer buf);
extern Oid simple_heap_insert(Relation relation, HeapTuple tup);
extern void simple_heap_delete(Relation relation, ItemPointer tid);
extern void simple_heap_update(Relation relation, ItemPointer otid,
HeapTuple tup);
extern void heap_markpos(HeapScanDesc scan);
extern void heap_restrpos(HeapScanDesc scan);
extern void heap_sync(Relation relation);
extern void heap_redo(XLogRecPtr lsn, XLogRecord *rptr);
extern void heap_desc(StringInfo buf, uint8 xl_info, char *rec);
extern void heap2_redo(XLogRecPtr lsn, XLogRecord *rptr);
extern void heap2_desc(StringInfo buf, uint8 xl_info, char *rec);
extern XLogRecPtr log_heap_move(Relation reln, Buffer oldbuf,
ItemPointerData from,
Buffer newbuf, HeapTuple newtup);
extern XLogRecPtr log_heap_clean(Relation reln, Buffer buffer,
OffsetNumber *redirected, int nredirected,
OffsetNumber *nowdead, int ndead,
OffsetNumber *nowunused, int nunused,
bool redirect_move);
extern XLogRecPtr log_heap_freeze(Relation reln, Buffer buffer,
TransactionId cutoff_xid,
OffsetNumber *offsets, int offcnt);
extern XLogRecPtr log_newpage(RelFileNode *rnode, BlockNumber blk, Page page);
/* in common/heaptuple.c */
extern Size heap_compute_data_size(TupleDesc tupleDesc,
Datum *values, bool *isnull);
extern void heap_fill_tuple(TupleDesc tupleDesc,
Datum *values, bool *isnull,
char *data, Size data_size,
uint16 *infomask, bits8 *bit);
extern bool heap_attisnull(HeapTuple tup, int attnum);
extern Datum nocachegetattr(HeapTuple tup, int attnum,
TupleDesc att, bool *isnull);
extern Datum heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
bool *isnull);
extern HeapTuple heap_copytuple(HeapTuple tuple);
extern void heap_copytuple_with_tuple(HeapTuple src, HeapTuple dest);
extern HeapTuple heap_form_tuple(TupleDesc tupleDescriptor,
Datum *values, bool *isnull);
extern HeapTuple heap_formtuple(TupleDesc tupleDescriptor,
Datum *values, char *nulls);
extern HeapTuple heap_modify_tuple(HeapTuple tuple,
TupleDesc tupleDesc,
Datum *replValues,
bool *replIsnull,
bool *doReplace);
extern HeapTuple heap_modifytuple(HeapTuple tuple,
TupleDesc tupleDesc,
Datum *replValues,
char *replNulls,
char *replActions);
extern void heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc,
Datum *values, bool *isnull);
extern void heap_deformtuple(HeapTuple tuple, TupleDesc tupleDesc,
Datum *values, char *nulls);
extern void heap_freetuple(HeapTuple htup);
extern MinimalTuple heap_form_minimal_tuple(TupleDesc tupleDescriptor,
Datum *values, bool *isnull);
extern void heap_free_minimal_tuple(MinimalTuple mtup);
extern MinimalTuple heap_copy_minimal_tuple(MinimalTuple mtup);
extern HeapTuple heap_tuple_from_minimal_tuple(MinimalTuple mtup);
extern MinimalTuple minimal_tuple_from_heap_tuple(HeapTuple htup);
extern HeapTuple heap_addheader(int natts, bool withoid,
Size structlen, void *structure);
/* in heap/pruneheap.c */
extern void heap_page_prune_opt(Relation relation, Buffer buffer,
TransactionId OldestXmin);
extern int heap_page_prune(Relation relation, Buffer buffer,
TransactionId OldestXmin,
bool redirect_move, bool report_stats);
extern void heap_get_root_tuples(Page page, OffsetNumber *root_offsets);
/* in heap/syncscan.c */
extern void ss_report_location(Relation rel, BlockNumber location);
extern BlockNumber ss_get_location(Relation rel, BlockNumber relnblocks);
extern void SyncScanShmemInit(void);
extern Size SyncScanShmemSize(void);
#endif /* HEAPAM_H */
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