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本篇内容主要讲解“怎么使用 PostgreSQL 的 pg_stat_statements”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让丸趣 TV 小编来带大家学习“怎么使用 PostgreSQL 的 pg_stat_statements”吧!
pg_stat_statements 提供了一种跟踪所有 SQL 语句的手段。
进入 pg_stat_statements 目录, 执行 make/make install
[pg12@localhost pg_stat_statements]$ ls
expected pg_stat_statements--1.4--1.5.sql pg_stat_statements.control
Makefile pg_stat_statements--1.4.sql pg_stat_statements.o
pg_stat_statements--1.0--1.1.sql pg_stat_statements--1.5--1.6.sql pg_stat_statements.so
pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.6--1.7.sql pg_stat_statements--unpackaged--1.0.sql
pg_stat_statements--1.2--1.3.sql pg_stat_statements.c sql
pg_stat_statements--1.3--1.4.sql pg_stat_statements.conf
[pg12@localhost pg_stat_statements]$ make
make -C ../../src/backend generated-headers
make[1]: Entering directory `/data/source/postgresql-12beta1/src/backend
make -C catalog distprep generated-header-symlinks
make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/catalog
make[2]: Nothing to be done for `distprep .
make[2]: Nothing to be done for `generated-header-symlinks .
make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/catalog
make -C utils distprep generated-header-symlinks
make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/utils
make[2]: Nothing to be done for `distprep .
make[2]: Nothing to be done for `generated-header-symlinks .
make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/utils
make[1]: Leaving directory `/data/source/postgresql-12beta1/src/backend
[pg12@localhost pg_stat_statements]$ make install
make -C ../../src/backend generated-headers
make[1]: Entering directory `/data/source/postgresql-12beta1/src/backend
make -C catalog distprep generated-header-symlinks
make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/catalog
make[2]: Nothing to be done for `distprep .
make[2]: Nothing to be done for `generated-header-symlinks .
make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/catalog
make -C utils distprep generated-header-symlinks
make[2]: Entering directory `/data/source/postgresql-12beta1/src/backend/utils
make[2]: Nothing to be done for `distprep .
make[2]: Nothing to be done for `generated-header-symlinks .
make[2]: Leaving directory `/data/source/postgresql-12beta1/src/backend/utils
make[1]: Leaving directory `/data/source/postgresql-12beta1/src/backend
/usr/bin/mkdir -p /appdb/xdb/pg12beta1/lib/postgresql
/usr/bin/mkdir -p /appdb/xdb/pg12beta1/share/postgresql/extension
/usr/bin/mkdir -p /appdb/xdb/pg12beta1/share/postgresql/extension
/usr/bin/install -c -m 755 pg_stat_statements.so /appdb/xdb/pg12beta1/lib/postgresql/pg_stat_statements.so
/usr/bin/install -c -m 644 ./pg_stat_statements.control /appdb/xdb/pg12beta1/share/postgresql/extension/
/usr/bin/install -c -m 644 ./pg_stat_statements--1.4.sql ./pg_stat_statements--1.6--1.7.sql ./pg_stat_statements--1.5--1.6.sql ./pg_stat_statements--1.4--1.5.sql ./pg_stat_statements--1.3--1.4.sql ./pg_stat_statements--1.2--1.3.sql ./pg_stat_statements--1.1--1.2.sql ./pg_stat_statements--1.0--1.1.sql ./pg_stat_statements--unpackaged--1.0.sql /appdb/xdb/pg12beta1/share/postgresql/extension/
[pg12@localhost pg_stat_statements]$使用前需在配置文件中添加预加载共享链接库, 否则会报错:
testdb=# create extension pg_stat_statements;
CREATE EXTENSION
testdb=# select * from pg_stat_statements;
psql: ERROR: pg_stat_statements must be loaded via shared_preload_libraries在 postgresql.conf 文件中修改 shared_preload_libraries 参数:
[pg12@localhost pg12db1]$ grep shared_preload postgresql.conf
shared_preload_libraries = pg_stat_statements # (change requires restart)注意: 修改该参数后需要重启数据库实例.
下面是简单的使用:
testdb=# \x
Expanded display is on.
testdb=# select * from pg_stat_statements;
-[ RECORD 1 ]-------+---------------------------------
userid | 10
dbid | 16384
queryid | 6343734953611294604
query | select * from pg_stat_statements
calls | 2
total_time | 0.618297
min_time | 0.303231
max_time | 0.315066
mean_time | 0.3091485
stddev_time | 0.00591750000000002
rows | 2
shared_blks_hit | 0
shared_blks_read | 0
shared_blks_dirtied | 0
shared_blks_written | 0
local_blks_hit | 0
local_blks_read | 0
local_blks_dirtied | 0
local_blks_written | 0
temp_blks_read | 0
temp_blks_written | 0
blk_read_time | 0
blk_write_time | 0
-[ RECORD 2 ]-------+---------------------------------
userid | 10
dbid | 16384
queryid | -2568307067200732111
query | select * from t1
calls | 1
total_time | 876.219199
min_time | 876.219199
max_time | 876.219199
mean_time | 876.219199
stddev_time | 0
rows | 1100000
shared_blks_hit | 0
shared_blks_read | 5946
shared_blks_dirtied | 0
shared_blks_written | 0
local_blks_hit | 0
local_blks_read | 0
local_blks_dirtied | 0
local_blks_written | 0
temp_blks_read | 0
temp_blks_written | 0
blk_read_time | 0
blk_write_time | 0查询汇总统计信息
testdb=# SELECT query,
(total_time / 1000 / 60) as total,
(total_time/calls) as avg
FROM pg_stat_statements
ORDER BY 1 DESC
LIMIT 100;
query | total | avg
-------------------------------------+------------------------+---------------------
SELECT +| 1.5928199999999998e-05 | 0.318564
(total_time / $1 / $2) as total, +| |
(total_time/calls) as avg, +| |
query +| |
FROM pg_stat_statements +| |
ORDER BY 1 DESC +| |
LIMIT $3 | |
SELECT +| 4.9146500000000005e-06 | 0.294879
(total_time / $1 / $2) as total, +| |
(total_time/calls) as avg +| |
FROM pg_stat_statements +| |
ORDER BY 1 DESC +| |
LIMIT $3 | |
select * from t1 | 0.014603653316666666 | 876.219199
select * from pg_stat_statements | 1.5696116666666667e-05 | 0.31392233333333336
(4 rows)
testdb=#
testdb=# SELECT
testdb-# query,
testdb-# round((total_time / 1000 / 60)::numeric,4) as total,
testdb-# round((total_time/calls)::numeric,4) as avg
testdb-# FROM pg_stat_statements
testdb-# WHERE query like %t1%
testdb-# ORDER BY 1 DESC
testdb-# LIMIT 100;
query | total | avg
--------------------------------+--------+----------
select * from t1 where id = $1 | 0.0022 | 129.9684
select * from t1 where id $1 | 0.0020 | 121.3334
select * from t1 | 0.0146 | 876.2192
(3 rows)查询条件中 id = xx, 实际值被替换为占位符 ($x).
到此，相信大家对“怎么使用 PostgreSQL 的 pg_stat_statements”有了更深的了解，不妨来实际操作一番吧！这里是丸趣 TV 网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
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