mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Teach pg_stat_statements not to ignore FOR UPDATE clauses

Browse Source 
Performance of a SELECT FOR UPDATE may be quite distinct from the
non-UPDATE version of the query, so treat all of the FOR UPDATE clause
as being significant for distinguishing queries.

Andrew Gierth and Vik Fearing, reviewed by Sergei Kornilov, Thomas
Munro, Tom Lane

Discussion: https://postgr.es/m/87h8e4hfwv.fsf@news-spur.riddles.org.uk
This commit is contained in:
Andrew Gierth 2019-07-14 12:07:40 +01:00
parent 0369f47366
commit 6e74c64bcf
3 changed files with 140 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

87
contrib/pg_stat_statements/expected/pg_stat_statements.out
View File

@ -354,6 +354,93 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
SELECT pg_stat_statements_reset() | 1 | 1
(5 rows)
--
-- queries with locking clauses
--
CREATE TABLE pgss_a (id integer PRIMARY KEY);
CREATE TABLE pgss_b (id integer PRIMARY KEY, a_id integer REFERENCES pgss_a);
SELECT pg_stat_statements_reset();
pg_stat_statements_reset
--------------------------
(1 row)
-- control query
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id;
id | id | a_id
----+----+------
(0 rows)
-- test range tables
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE;
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a;
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b;
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a, pgss_b; -- matches plain "FOR UPDATE"
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b, pgss_a;
id | id | a_id
----+----+------
(0 rows)
-- test strengths
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR NO KEY UPDATE;
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR SHARE;
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR KEY SHARE;
id | id | a_id
----+----+------
(0 rows)
-- test wait policies
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE NOWAIT;
id | id | a_id
----+----+------
(0 rows)
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE SKIP LOCKED;
id | id | a_id
----+----+------
(0 rows)
SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
calls | query
-------+------------------------------------------------------------------------------------------
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR KEY SHARE
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR NO KEY UPDATE
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR SHARE
2 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE NOWAIT
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b, pgss_a
1 | SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE SKIP LOCKED
1 | SELECT pg_stat_statements_reset()
(11 rows)
DROP TABLE pgss_a, pgss_b CASCADE;
--
-- utility commands
--

23
contrib/pg_stat_statements/pg_stat_statements.c
View File

@ -333,6 +333,7 @@ static void AppendJumble(pgssJumbleState *jstate,
const unsigned char *item, Size size);
static void JumbleQuery(pgssJumbleState *jstate, Query *query);
static void JumbleRangeTable(pgssJumbleState *jstate, List *rtable);
static void JumbleRowMarks(pgssJumbleState *jstate, List *rowMarks);
static void JumbleExpr(pgssJumbleState *jstate, Node *node);
static void RecordConstLocation(pgssJumbleState *jstate, int location);
static char *generate_normalized_query(pgssJumbleState *jstate, const char *query,
@ -2430,7 +2431,7 @@ JumbleQuery(pgssJumbleState *jstate, Query *query)
JumbleExpr(jstate, (Node *) query->sortClause);
JumbleExpr(jstate, query->limitOffset);
JumbleExpr(jstate, query->limitCount);
/* we ignore rowMarks */
JumbleRowMarks(jstate, query->rowMarks);
JumbleExpr(jstate, query->setOperations);
}
@ -2489,6 +2490,26 @@ JumbleRangeTable(pgssJumbleState *jstate, List *rtable)
}
}
/*
* Jumble a rowMarks list
*/
static void
JumbleRowMarks(pgssJumbleState *jstate, List *rowMarks)
{
ListCell *lc;
foreach(lc, rowMarks)
{
RowMarkClause *rowmark = lfirst_node(RowMarkClause, lc);
if (!rowmark->pushedDown)
{
APP_JUMB(rowmark->rti);
APP_JUMB(rowmark->strength);
APP_JUMB(rowmark->waitPolicy);
}
}
}
/*
* Jumble an expression tree
*

31
contrib/pg_stat_statements/sql/pg_stat_statements.sql
View File

@ -177,6 +177,37 @@ SELECT PLUS_ONE(1);
SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
--
-- queries with locking clauses
--
CREATE TABLE pgss_a (id integer PRIMARY KEY);
CREATE TABLE pgss_b (id integer PRIMARY KEY, a_id integer REFERENCES pgss_a);
SELECT pg_stat_statements_reset();
-- control query
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id;
-- test range tables
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_a, pgss_b; -- matches plain "FOR UPDATE"
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE OF pgss_b, pgss_a;
-- test strengths
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR NO KEY UPDATE;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR SHARE;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR KEY SHARE;
-- test wait policies
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE NOWAIT;
SELECT * FROM pgss_a JOIN pgss_b ON pgss_b.a_id = pgss_a.id FOR UPDATE SKIP LOCKED;
SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
DROP TABLE pgss_a, pgss_b CASCADE;
--
-- utility commands
--