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

Commitd729f1e

Browse files
committed
Move I/O before the index_update_stats() buffer lock region.
Commita07e03f enlarged the work donehere under the pg_class heap buffer lock. Two preexisting actions arebest done before holding that lock. Both RelationGetNumberOfBlocks()and visibilitymap_count() do I/O, and the latter might exclusive-lock avisibility map buffer. Moving these reduces contention and risk ofundetected LWLock deadlock. Back-patch to v12, like that commit.Discussion:https://postgr.es/m/20241031200139.b4@rfd.leadboat.com
1 parent4b0f7d6 commitd729f1e

File tree

1 file changed

+36
-9
lines changed

1 file changed

+36
-9
lines changed

‎src/backend/catalog/index.c

Lines changed: 36 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -2787,6 +2787,9 @@ index_update_stats(Relation rel,
27872787
boolhasindex,
27882788
doublereltuples)
27892789
{
2790+
boolupdate_stats;
2791+
BlockNumberrelpages;
2792+
BlockNumberrelallvisible;
27902793
Oidrelid=RelationGetRelid(rel);
27912794
Relationpg_class;
27922795
ScanKeyDatakey[1];
@@ -2795,6 +2798,38 @@ index_update_stats(Relation rel,
27952798
Form_pg_classrd_rel;
27962799
booldirty;
27972800

2801+
/*
2802+
* As a special hack, if we are dealing with an empty table and the
2803+
* existing reltuples is -1, we leave that alone. This ensures that
2804+
* creating an index as part of CREATE TABLE doesn't cause the table to
2805+
* prematurely look like it's been vacuumed. The rd_rel we modify may
2806+
* differ from rel->rd_rel due to e.g. commit of concurrent GRANT, but the
2807+
* commands that change reltuples take locks conflicting with ours. (Even
2808+
* if a command changed reltuples under a weaker lock, this affects only
2809+
* statistics for an empty table.)
2810+
*/
2811+
if (reltuples==0&&rel->rd_rel->reltuples<0)
2812+
reltuples=-1;
2813+
2814+
update_stats=reltuples >=0;
2815+
2816+
/*
2817+
* Finish I/O and visibility map buffer locks before
2818+
* systable_inplace_update_begin() locks the pg_class buffer. The rd_rel
2819+
* we modify may differ from rel->rd_rel due to e.g. commit of concurrent
2820+
* GRANT, but no command changes a relkind from non-index to index. (Even
2821+
* if one did, relallvisible doesn't break functionality.)
2822+
*/
2823+
if (update_stats)
2824+
{
2825+
relpages=RelationGetNumberOfBlocks(rel);
2826+
2827+
if (rel->rd_rel->relkind!=RELKIND_INDEX)
2828+
visibilitymap_count(rel,&relallvisible,NULL);
2829+
else/* don't bother for indexes */
2830+
relallvisible=0;
2831+
}
2832+
27982833
/*
27992834
* We always update the pg_class row using a non-transactional,
28002835
* overwrite-in-place update. There are several reasons for this:
@@ -2848,16 +2883,8 @@ index_update_stats(Relation rel,
28482883
dirty= true;
28492884
}
28502885

2851-
if (reltuples >=0)
2886+
if (update_stats)
28522887
{
2853-
BlockNumberrelpages=RelationGetNumberOfBlocks(rel);
2854-
BlockNumberrelallvisible;
2855-
2856-
if (rd_rel->relkind!=RELKIND_INDEX)
2857-
visibilitymap_count(rel,&relallvisible,NULL);
2858-
else/* don't bother for indexes */
2859-
relallvisible=0;
2860-
28612888
if (rd_rel->relpages!= (int32)relpages)
28622889
{
28632890
rd_rel->relpages= (int32)relpages;

0 commit comments

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