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Create a routine PageIndexMultiDelete() that replaces a loop around

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PageIndexTupleDelete() with a single pass of compactification ---
logic mostly lifted from PageRepairFragmentation.  I noticed while
profiling that a VACUUM that's cleaning up a whole lot of deleted
tuples would spend as much as a third of its CPU time in
PageIndexTupleDelete; not too surprising considering the loop method
was roughly O(N^2) in the number of tuples involved.
This commit is contained in:
Tom Lane
2005-03-22 06:17:03 +00:00
parent 775d28302c
commit 94e03330cb
4 changed files with 144 additions and 19 deletions
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11
src/backend/access/nbtree/nbtpage.c
View File

@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.81 2004/12/31 21:59:22 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.82 2005/03/22 06:17:03 tgl Exp $
*
* NOTES
* Postgres btree pages look like ordinary relation pages. The opaque
@@ -639,17 +639,12 @@ _bt_delitems(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems)
{
Page page = BufferGetPage(buf);
int i;
/* No ereport(ERROR) until changes are logged */
START_CRIT_SECTION();
/*
* Delete the items in reverse order so we don't have to think about
* adjusting item numbers for previous deletions.
*/
for (i = nitems - 1; i >= 0; i--)
PageIndexTupleDelete(page, itemnos[i]);
/* Fix the page */
PageIndexMultiDelete(page, itemnos, nitems);
/* XLOG stuff */
if (!rel->rd_istemp)

9
src/backend/access/nbtree/nbtxlog.c
View File

@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.19 2004/12/31 21:59:22 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.20 2005/03/22 06:17:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -411,12 +411,7 @@ btree_xlog_delete(bool redo, XLogRecPtr lsn, XLogRecord *record)
unused = (OffsetNumber *) ((char *) xlrec + SizeOfBtreeDelete);
unend = (OffsetNumber *) ((char *) xlrec + record->xl_len);
/* be careful to delete from back to front */
while (unused < unend)
{
unend--;
PageIndexTupleDelete(page, *unend);
}
PageIndexMultiDelete(page, unused, unend - unused);
}
PageSetLSN(page, lsn);