1、查询链接数
SELECT sum(numbackends) FROM pg_stat_database;
2、查看死锁状态
select pid, usename, pg_blocking_pids(pid) as blocked_by, query as blocked_query from pg_stat_activity where cardinality(pg_blocking_pids(pid)) > 0;
3、删除死锁进程
SELECT pg_cancel_backend(__pid__); SELECT pg_terminate_backend(__pid__);
4、备份数据库
# sql文件 pg_dump dangerousdb > db.sql # tar文件 pg_dump -U postgres -F c dangerousdb > dangerousdb.tar # gz文件 pg_dump -U postgres dangerousdb | gzip > dangerousdb.gz
5、还原数据库
# 已经存在数据库 pg_restore -U postgres -Ft -d dbcooper < dbcooper.tar # 创建新数据库 pg_restore -U postgres -Ft -C -d dbcooper < dbcooper.tar #
6、插入数据
插入单条数据
INSERT INTO TABLE_1 ( column_1, column_2, column_3 ) values( column_1, column_2, column_3 )
插入多条数据
INSERT INTO TABLE_1 ( column_1, column_2, column_3 ) values( column_1, column_2, column_3 ),( column_1, column_2, column_3 )...
从一张表查询到的数据插入到另一张表
INSERT INTO TABLE_1 ( column_1, column_2, column_3 ) SELECT column_1, column_2, column_3 FROM TABLE_2 where TABLE_2条件;
7 、查询pg中单张表的大小（不包含索引）
select
pg_size_pretty(pg_relation_size('schema.table_name'));
8、查询数据库中所有表的大小
select relname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_tables where schemaname = 'public' order by pg_relation_size(relid) desc;
9、按顺序查看索引
select indexrelname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_indexes where schemaname = 'public' order by pg_relation_size(relid) desc;
10 、查询数据库的大小
select pg_database.datname, pg_size_pretty (pg_database_size(pg_database.datname)) as size from pg_database;
11、查询被锁定的表
select pg_class.relname as table, pg_database.datname as database, pid, mode, granted from pg_locks, pg_class, pg_database where pg_locks.relation = pg_class.oid and pg_locks.database = pg_database.oid;
12 、查询一个Schema下面的所有表的总大小（单位MB，包括索引和数据）
select schemaname , round(sum(pg_total_relation_size(schemaname || '.' || tablename))/ 1024 / 1024) "Size_MB" from pg_tables where schemaname = '' group by 1;
13 、查询所有表的大小并排序（包含索引）
select
table_schema || '.' || table_name as table_full_name,
pg_size_pretty(pg_total_relation_size('"' || table_schema || '"."' || table_name || '"')) as size
from
information_schema.tables
order by
pg_total_relation_size('"' || table_schema || '"."' || table_name || '"') desc
limit 20;
14 、查询表大小按大小排序并分离data与index
select
table_name,
pg_size_pretty(table_size) as table_size,
pg_size_pretty(indexes_size) as indexes_size,
pg_size_pretty(total_size) as total_size
from
(
select
table_name,
pg_table_size(table_name) as table_size,
pg_indexes_size(table_name) as indexes_size,
pg_total_relation_size(table_name) as total_size
from
(
select
('"' || table_schema || '"."' || table_name || '"') as table_name
from
information_schema.tables) as all_tables
order by
total_size desc) as pretty_sizes;
或者
select
table_name,
pg_size_pretty(table_size) as table_size,
pg_size_pretty(indexes_size) as indexes_size,
pg_size_pretty(total_size) as total_size
from
(
select
table_name,
pg_table_size(table_name) as table_size,
pg_indexes_size(table_name) as indexes_size,
pg_total_relation_size(table_name) as total_size
from
(
select
('' || table_schema || '.' || table_name || '') as table_name
from
information_schema.tables) as all_tables
order by
total_size desc) as pretty_sizes;
到此这篇关于postgresql 常用SQL语句小结的文章就介绍到这了,更多相关postgresql 常用SQL内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家！