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Commit35e9b1c

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committed
Clean up a couple of ad-hoc computations of the maximum number of tuples
on a page, as suggested by ITAGAKI Takahiro. Also, change a few placesthat were using some other estimates of max-items-per-page to consistentlyuse MaxOffsetNumber. This is conservatively large --- we could have usedthe new MaxHeapTuplesPerPage macro, or a similar one for index tuples ---but those places are simply declaring a fixed-size buffer and assuming itwill work, rather than actively testing for overrun. It seems safer tosize these buffers in a way that can't overflow even if the page iscorrupt.
1 parent962a4bb commit35e9b1c

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6 files changed

+25
-18
lines changed

6 files changed

+25
-18
lines changed

‎src/backend/access/gist/gistvacuum.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.6 2005/06/30 17:52:14 teodor Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.7 2005/09/02 19:02:19 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -52,7 +52,7 @@ gistVacuumUpdate( GistVacuum *gv, BlockNumber blkno, bool needunion ) {
5252
intlenaddon=4,curlenaddon=0,ntodelete=0;
5353
IndexTupleidxtuple,*addon=NULL;
5454
boolneedwrite=false;
55-
OffsetNumbertodelete[BLCKSZ/SizeOfIptrData];
55+
OffsetNumbertodelete[MaxOffsetNumber];
5656
ItemPointerData*completed=NULL;
5757
intncompleted=0,lencompleted=16;
5858

@@ -439,7 +439,7 @@ gistbulkdelete(PG_FUNCTION_ARGS) {
439439
page= (Page)BufferGetPage(buffer);
440440

441441
if (GistPageIsLeaf(page) ) {
442-
OffsetNumbertodelete[BLCKSZ/SizeOfIptrData];
442+
OffsetNumbertodelete[MaxOffsetNumber];
443443
intntodelete=0;
444444

445445
LockBuffer(buffer,GIST_UNLOCK);

‎src/backend/access/nbtree/nbtree.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@
1212
* Portions Copyright (c) 1994, Regents of the University of California
1313
*
1414
* IDENTIFICATION
15-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.130 2005/05/11 06:24:53 neilc Exp $
15+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.131 2005/09/02 19:02:19 tgl Exp $
1616
*
1717
*-------------------------------------------------------------------------
1818
*/
@@ -584,7 +584,7 @@ btbulkdelete(PG_FUNCTION_ARGS)
584584
IndexBulkDeleteResult*result;
585585
doubletuples_removed;
586586
doublenum_index_tuples;
587-
OffsetNumberdeletable[BLCKSZ /sizeof(OffsetNumber)];
587+
OffsetNumberdeletable[MaxOffsetNumber];
588588
intndeletable;
589589
Bufferbuf;
590590
BlockNumbernum_pages;

‎src/backend/commands/vacuum.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
*
1414
*
1515
* IDENTIFICATION
16-
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.313 2005/08/20 00:39:54 tgl Exp $
16+
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.314 2005/09/02 19:02:19 tgl Exp $
1717
*
1818
*-------------------------------------------------------------------------
1919
*/
@@ -2407,7 +2407,7 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
24072407
{
24082408
Bufferbuf;
24092409
Pagepage;
2410-
OffsetNumberunused[BLCKSZ /sizeof(OffsetNumber)];
2410+
OffsetNumberunused[MaxOffsetNumber];
24112411
OffsetNumberoffnum,
24122412
maxoff;
24132413
intuncnt;
@@ -2896,7 +2896,7 @@ vacuum_heap(VRelStats *vacrelstats, Relation onerel, VacPageList vacuum_pages)
28962896
staticvoid
28972897
vacuum_page(Relationonerel,Bufferbuffer,VacPagevacpage)
28982898
{
2899-
OffsetNumberunused[BLCKSZ /sizeof(OffsetNumber)];
2899+
OffsetNumberunused[MaxOffsetNumber];
29002900
intuncnt;
29012901
Pagepage=BufferGetPage(buffer);
29022902
ItemIditemid;

‎src/backend/commands/vacuumlazy.c

Lines changed: 4 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -31,7 +31,7 @@
3131
*
3232
*
3333
* IDENTIFICATION
34-
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.57 2005/08/20 23:26:13 tgl Exp $
34+
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.58 2005/09/02 19:02:20 tgl Exp $
3535
*
3636
*-------------------------------------------------------------------------
3737
*/
@@ -60,9 +60,6 @@
6060
#defineREL_TRUNCATE_MINIMUM1000
6161
#defineREL_TRUNCATE_FRACTION16
6262

63-
/* MAX_TUPLES_PER_PAGE can be a conservative upper limit */
64-
#defineMAX_TUPLES_PER_PAGE((int) (BLCKSZ / sizeof(HeapTupleHeaderData)))
65-
6663

6764
typedefstructLVRelStats
6865
{
@@ -259,7 +256,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
259256
* dead-tuple TIDs, pause and do a cycle of vacuuming before we
260257
* tackle this page.
261258
*/
262-
if ((vacrelstats->max_dead_tuples-vacrelstats->num_dead_tuples)<MAX_TUPLES_PER_PAGE&&
259+
if ((vacrelstats->max_dead_tuples-vacrelstats->num_dead_tuples)<MaxHeapTuplesPerPage&&
263260
vacrelstats->num_dead_tuples>0)
264261
{
265262
/* Remove index entries */
@@ -554,7 +551,7 @@ static int
554551
lazy_vacuum_page(Relationonerel,BlockNumberblkno,Bufferbuffer,
555552
inttupindex,LVRelStats*vacrelstats)
556553
{
557-
OffsetNumberunused[BLCKSZ /sizeof(OffsetNumber)];
554+
OffsetNumberunused[MaxOffsetNumber];
558555
intuncnt;
559556
Pagepage=BufferGetPage(buffer);
560557
ItemIditemid;
@@ -960,7 +957,7 @@ lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks)
960957
maxtuples= (maintenance_work_mem*1024L) /sizeof(ItemPointerData);
961958
maxtuples=Min(maxtuples,INT_MAX);
962959
/* stay sane if small maintenance_work_mem */
963-
maxtuples=Max(maxtuples,MAX_TUPLES_PER_PAGE);
960+
maxtuples=Max(maxtuples,MaxHeapTuplesPerPage);
964961

965962
vacrelstats->num_dead_tuples=0;
966963
vacrelstats->max_dead_tuples= (int)maxtuples;

‎src/backend/nodes/tidbitmap.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@
2323
* Copyright (c) 2003-2005, PostgreSQL Global Development Group
2424
*
2525
* IDENTIFICATION
26-
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.6 2005/08/28 22:47:20 tgl Exp $
26+
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.7 2005/09/02 19:02:20 tgl Exp $
2727
*
2828
*-------------------------------------------------------------------------
2929
*/
@@ -42,7 +42,7 @@
4242
* the per-page bitmaps variable size. We just legislate that the size
4343
* is this:
4444
*/
45-
#defineMAX_TUPLES_PER_PAGE((BLCKSZ - 1) / MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) + sizeof(ItemIdData)) + 1)
45+
#defineMAX_TUPLES_PER_PAGEMaxHeapTuplesPerPage
4646

4747
/*
4848
* When we have to switch over to lossy storage, we use a data structure

‎src/include/access/htup.h

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.76 2005/08/20 00:39:59 tgl Exp $
10+
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.77 2005/09/02 19:02:20 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -323,6 +323,16 @@ do { \
323323
#defineMaxTupleSize\
324324
(BLCKSZ - MAXALIGN(sizeof(PageHeaderData) + MaxSpecialSpace))
325325

326+
/*
327+
* MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
328+
* fit on one heap page. (Note that indexes could have more, because they
329+
* use a smaller tuple header.) We arrive at the divisor because each tuple
330+
* must be maxaligned, and it must have an associated item pointer.
331+
*/
332+
#defineMaxHeapTuplesPerPage\
333+
((int) ((BLCKSZ - offsetof(PageHeaderData, pd_linp)) / \
334+
(MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData))))
335+
326336
/*
327337
* MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
328338
* data fields of char(n) and similar types. It need not have anything

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