database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-31 17:02:12 +03:00
Code Activity

Clean up a couple of ad-hoc computations of the maximum number of tuples

Browse Source 
on a page, as suggested by ITAGAKI Takahiro.  Also, change a few places
that were using some other estimates of max-items-per-page to consistently
use MaxOffsetNumber.  This is conservatively large --- we could have used
the new MaxHeapTuplesPerPage macro, or a similar one for index tuples ---
but those places are simply declaring a fixed-size buffer and assuming it
will work, rather than actively testing for overrun.  It seems safer to
size these buffers in a way that can't overflow even if the page is
corrupt.
This commit is contained in:
Tom Lane
2005-09-02 19:02:20 +00:00
parent 962a4bb69f
commit 35e9b1cc1e
6 changed files with 25 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/backend/commands/vacuumlazy.c
View File

@@ -31,7 +31,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.57 2005/08/20 23:26:13 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.58 2005/09/02 19:02:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -60,9 +60,6 @@
#define REL_TRUNCATE_MINIMUM 1000
#define REL_TRUNCATE_FRACTION 16
/* MAX_TUPLES_PER_PAGE can be a conservative upper limit */
#define MAX_TUPLES_PER_PAGE ((int) (BLCKSZ / sizeof(HeapTupleHeaderData)))
typedef struct LVRelStats
{
@@ -259,7 +256,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
* dead-tuple TIDs, pause and do a cycle of vacuuming before we
* tackle this page.
*/
if ((vacrelstats->max_dead_tuples - vacrelstats->num_dead_tuples) < MAX_TUPLES_PER_PAGE &&
if ((vacrelstats->max_dead_tuples - vacrelstats->num_dead_tuples) < MaxHeapTuplesPerPage &&
vacrelstats->num_dead_tuples > 0)
{
/* Remove index entries */
@@ -554,7 +551,7 @@ static int
lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
int tupindex, LVRelStats *vacrelstats)
{
OffsetNumber unused[BLCKSZ / sizeof(OffsetNumber)];
OffsetNumber unused[MaxOffsetNumber];
int uncnt;
Page page = BufferGetPage(buffer);
ItemId itemid;
@@ -960,7 +957,7 @@ lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks)
maxtuples = (maintenance_work_mem * 1024L) / sizeof(ItemPointerData);
maxtuples = Min(maxtuples, INT_MAX);
/* stay sane if small maintenance_work_mem */
maxtuples = Max(maxtuples, MAX_TUPLES_PER_PAGE);
maxtuples = Max(maxtuples, MaxHeapTuplesPerPage);
vacrelstats->num_dead_tuples = 0;
vacrelstats->max_dead_tuples = (int) maxtuples;