Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commitc17abc1

Browse files
committed
Fix logic error in tbm_intersect: the intersection of a normal page and
a lossy page has to be lossy, because we don't know exactly which tupleson the page should remain part of the bitmap. Per Jie Zhang.
1 parenteaa5d52 commitc17abc1

File tree

1 file changed

+23
-6
lines changed

1 file changed

+23
-6
lines changed

‎src/backend/nodes/tidbitmap.c‎

Lines changed: 23 additions & 6 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 1.4 2005/05/29 04:23:03 tgl Exp $
26+
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.5 2005/07/24 02:25:26 tgl Exp $
2727
*
2828
*-------------------------------------------------------------------------
2929
*/
@@ -135,7 +135,8 @@ struct TIDBitmap
135135

136136
/* Local function prototypes */
137137
staticvoidtbm_union_page(TIDBitmap*a,constPagetableEntry*bpage);
138-
staticbooltbm_intersect_page(PagetableEntry*apage,constTIDBitmap*b);
138+
staticbooltbm_intersect_page(TIDBitmap*a,PagetableEntry*apage,
139+
constTIDBitmap*b);
139140
staticconstPagetableEntry*tbm_find_pageentry(constTIDBitmap*tbm,
140141
BlockNumberpageno);
141142
staticPagetableEntry*tbm_get_pageentry(TIDBitmap*tbm,BlockNumberpageno);
@@ -382,7 +383,7 @@ tbm_intersect(TIDBitmap *a, const TIDBitmap *b)
382383
/* Scan through chunks and pages in a, try to match to b */
383384
if (a->status==TBM_ONE_PAGE)
384385
{
385-
if (tbm_intersect_page(&a->entry1,b))
386+
if (tbm_intersect_page(a,&a->entry1,b))
386387
{
387388
/* Page is now empty, remove it from a */
388389
Assert(!a->entry1.ischunk);
@@ -401,7 +402,7 @@ tbm_intersect(TIDBitmap *a, const TIDBitmap *b)
401402
hash_seq_init(&status,a->pagetable);
402403
while ((apage= (PagetableEntry*)hash_seq_search(&status))!=NULL)
403404
{
404-
if (tbm_intersect_page(apage,b))
405+
if (tbm_intersect_page(a,apage,b))
405406
{
406407
/* Page or chunk is now empty, remove it from a */
407408
if (apage->ischunk)
@@ -424,7 +425,7 @@ tbm_intersect(TIDBitmap *a, const TIDBitmap *b)
424425
* Returns TRUE if apage is now empty and should be deleted from a
425426
*/
426427
staticbool
427-
tbm_intersect_page(PagetableEntry*apage,constTIDBitmap*b)
428+
tbm_intersect_page(TIDBitmap*a,PagetableEntry*apage,constTIDBitmap*b)
428429
{
429430
constPagetableEntry*bpage;
430431
intwordnum;
@@ -470,7 +471,23 @@ tbm_intersect_page(PagetableEntry *apage, const TIDBitmap *b)
470471
}
471472
elseif (tbm_page_is_lossy(b,apage->blockno))
472473
{
473-
/* page is lossy in b, cannot clear any bits */
474+
/*
475+
* When the page is lossy in b, we have to mark it lossy in a too.
476+
* We know that no bits need be set in bitmap a, but we do not know
477+
* which ones should be cleared, and we have no API for "at most
478+
* these tuples need be checked". (Perhaps it's worth adding that?)
479+
*/
480+
tbm_mark_page_lossy(a,apage->blockno);
481+
482+
/*
483+
* Note: tbm_mark_page_lossy will have removed apage from a, and
484+
* may have inserted a new lossy chunk instead. We can continue the
485+
* same seq_search scan at the caller level, because it does not
486+
* matter whether we visit such a new chunk or not: it will have
487+
* only the bit for apage->blockno set, which is correct.
488+
*
489+
* We must return false here since apage was already deleted.
490+
*/
474491
return false;
475492
}
476493
else

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp