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 = '<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;
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