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PostgreSQL中，如何安装pg_stat_statements，网上有很多这方面的论述。这里说说如何在PPAS下安装它：
实验一：首先，看是否可以不安装，直接拿来用：
[root@rhjp001 ~]# su - enterprisedb -bash-3.2$ pwd /opt/PostgresPlus/9.2AS -bash-3.2$ ./bin/psql -d edb psql (9.2.1.3) "help" でヘルプを表示します. edb=# select count(*) from pg_stat_statements; ERROR: pg_stat_statements must be loaded via shared_preload_libraries edb=#
实验二：直接创建：
edb=# create extension pg_stat_statments; ERROR: 拡張機能の制御ファイル "/opt/PostgresPlus/9.2AS/share/extension/pg_stat_statments.control" をオープンできませんでした: そのようなファイルやディレクトリはありません edb=#
实验三：改配置文件后，再创建：
-bash-3.2$ pwd /opt/PostgresPlus/9.2AS/data -bash-3.2$ vim postgresql.conf -bash-3.2$ cat postgresql.conf | grep preload shared_preload_libraries = '$libdir/dbms_pipe,$libdir/edb_gen,pg_stat_statements' #local_preload_libraries = '' -bash-3.2$
重新启动后，创建，其实已经不用创建了。
[root@rhjp001 ~]# su - enterprisedb -bash-3.2$ pwd /opt/PostgresPlus/9.2AS -bash-3.2$ ./bin/psql -d edb psql (9.2.1.3) "help" でヘルプを表示します. edb=# create extension pg_stat_statements; ERROR: 拡張機能 "pg_stat_statements" はすでに存在します edb=#
[root@rhjp001 ~]# su - enterprisedb -bash-3.2$ ./bin/psql -d edb psql (9.2.1.3) "help" でヘルプを表示します. edb=# select count(*) from pg_stat_statements; count ------- 47 (1 行) edb=#
也就是说，其实在PPAS安装好之后，如果想要使用 pg_stat_statements ，只要配置postgresql.conf的 shared_preload_libraries 就可以了。
卸载ppas，重新安装，然后再重新开始吧：
配置postgresql.conf：
把 shared_preload_libraries = '$libdir/dbms_pipe,$libdir/edb_gen'
改成：
shared_preload_libraries = '$libdir/dbms_pipe,$libdir/edb_gen,pg_stat_statements'
重新启动数据库： service ppas-9.2 restart
-bash-3.2$ ./bin/psql -d edb psql (9.2.1.3) "help" でヘルプを表示します. edb=# select count(*) from pg_stat_statements; count ------- 42 (1 行) edb=#
这个pg_stat_statements，主要可以用于区分运行最慢的sql文：
例如：
edb=# \d pg_stat_statements; ビュー "enterprisedb.pg_stat_statements" 列 | 型 | 修飾語 ---------------------+------------------+-------- userid | oid | dbid | oid | query | text | calls | bigint | total_time | double precision | rows | bigint | shared_blks_hit | bigint | shared_blks_read | bigint | shared_blks_dirtied | bigint | shared_blks_written | bigint | local_blks_hit | bigint | local_blks_read | bigint | local_blks_dirtied | bigint | local_blks_written | bigint | temp_blks_read | bigint | temp_blks_written | bigint | blk_read_time | double precision | blk_write_time | double precision | edb=#
查找最慢的10条sql文（这里用的是累计时间）
edb=# select * from pg_stat_statements order by total_time desc limit 10; -[ RECORD 1 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | drop extension pg_stat_statements; calls | 2 total_time | 3099.557 rows | 0 shared_blks_hit | 673 shared_blks_read | 27 shared_blks_dirtied | 9 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 | 14000 query | create database gaodb owner gao; calls | 1 total_time | 2068.82 rows | 0 shared_blks_hit | 54 shared_blks_read | 4 shared_blks_dirtied | 7 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 3 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | CREATE TEMP TABLE pga_tmp_zombies(jagpid int4) calls | 3 total_time | 1061.702 rows | 0 shared_blks_hit | 479 shared_blks_read | 109 shared_blks_dirtied | 37 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 4 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | SELECT count(*) As count, pg_backend_pid() AS pid FROM pg_class cl JOIN pg_na mespace ns ON ns.oid=relnamespace WHERE relname=? AND nspname=? calls | 3 total_time | 929.614 rows | 3 shared_blks_hit | 6 shared_blks_read | 15 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 5 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | SELECT COUNT(*) FROM pg_proc WHERE proname = ? AND pronamespace = ( SELECT oid FROM pg_namespace WHERE nspname = ?) AND prorettype = (SELECT oid ROM pg_type WHERE typnam e = ?) AND proargtypes = ? calls | 3 total_time | 337.312 rows | 3 shared_blks_hit | 15 shared_blks_read | 15 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 6 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | SELECT pgagent.pgagent_schema_version() calls | 3 total_time | 321.264 rows | 3 shared_blks_hit | 12 shared_blks_read | 12 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 7 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | DROP TABLE pga_tmp_zombies calls | 3 total_time | 282.334 rows | 0 shared_blks_hit | 360 shared_blks_read | 21 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 8 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 10 dbid | 14000 query | create extension pg_stat_statements; calls | 1 total_time | 155.641 rows | 0 shared_blks_hit | 585 shared_blks_read | 22 shared_blks_dirtied | 25 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 9 ]-------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 16684 dbid | 16685 query | create table gaotab(id integer); calls | 1 total_time | 143.838 rows | 0 shared_blks_hit | 195 shared_blks_read | 59 shared_blks_dirtied | 21 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 10 ]------+------------------------------------------------------------------------------ --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------- userid | 16684 dbid | 16685 query | select pg_available_extensions(); calls | 2 total_time | 92.16 rows | 100 shared_blks_hit | 5 shared_blks_read | 1 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 edb=#
需要注意，只有管理员用户才可以看到这个视图。
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磨砺技术珠矶，践行数据之道，追求卓越价值