PostgreSQL 查看数据库,索引,表,表空间大小的示例代码

Tags: postgresql
一、简介

PostgreSQL 提供了多个系统管理函数来查看表,索引,表空间及数据库的大小,下面详细介绍一下。

二、数据库对象尺寸函数

函数名 返回类型 描述
pg_column_size(any) int 存储一个指定的数值需要的字节数(可能压缩过)
pg_database_size(oid) bigint 指定OID的数据库使用的磁盘空间
pg_database_size(name) bigint 指定名称的数据库使用的磁盘空间
pg_indexes_size(regclass) bigint 关联指定表OID或表名的表索引的使用总磁盘空间
pg_relation_size(relation regclass, fork text) bigint 指定OID或名的表或索引,通过指定fork('main', 'fsm' 或'vm')所使用的磁盘空间
pg_relation_size(relation regclass) bigint pg_relation_size(..., 'main')的缩写
pg_size_pretty(bigint) text Converts a size in bytes expressed as a 64-bit integer into a human-readable format with size units
pg_size_pretty(numeric) text 把以字节计算的数值转换成一个人类易读的尺寸单位
pg_table_size(regclass) bigint 指定表OID或表名的表使用的磁盘空间,除去索引(但是包含TOAST,自由空间映射和可视映射)
pg_tablespace_size(oid) bigint 指定OID的表空间使用的磁盘空间
pg_tablespace_size(name) bigint 指定名称的表空间使用的磁盘空间
pg_total_relation_size(regclass) bigint 指定表OID或表名使用的总磁盘空间,包括所有索引和TOAST数据

三、实例讲解

3.1 查看存储一个指定的数值需要的字节数


david=# select pg_column_size(1);    
 pg_column_size
----------------
(1 row)

david=# select pg_column_size(10000);
 pg_column_size
----------------
(1 row)

david=# select pg_column_size('david');
 pg_column_size
----------------
(1 row)

david=# select pg_column_size('hello,world');
 pg_column_size
----------------
(1 row)

david=# select pg_column_size('2013-04-18 15:17:21.622885+08');
 pg_column_size
----------------
(1 row)

david=# select pg_column_size('中国');                        
 pg_column_size
----------------
(1 row)

david=#

3.2 查看数据库大小

查看原始数据


david=# \d test
              Table "public.test"
  Column   |         Type          | Modifiers
-----------+-----------------------+-----------
 id        | integer               |
 name      | character varying(20) |
 gender    | boolean               |
 join_date | date                  |
 dept      | character(4)          |
Indexes:
    "idx_join_date_test" btree (join_date)
    "idx_test" btree (id)

david=# select count(1) from test;
  count 
---------
(1 row)

david=#

查看david 数据库大小


david=# select pg_database_size('david');
 pg_database_size
------------------
(1 row)

david=#

查看所有数据库大小


david=# select pg_database.datname, pg_database_size(pg_database.datname) AS size from pg_database;               
  datname  |    size    
-----------+-------------
 template0 |     6513156
 postgres  |     6657144
 jboss     |     6521348
 bugs      |     6521348
 david     |   190534776
 BMCV3     | 28147135608
 mydb      |    10990712
 template1 |     6521348
(8 rows)

david=#

这样查出来的结果,看上去太长了,不太容易读数。

3.3 以人性化的方式显示大小


david=# select pg_size_pretty(pg_database_size('david'));
 pg_size_pretty
----------------
MB
(1 row)

david=#

3.4 查看单索引大小


david=# select pg_relation_size('idx_test');
 pg_relation_size
------------------
(1 row)

david=# select pg_size_pretty(pg_relation_size('idx_test'));
 pg_size_pretty
----------------
MB
(1 row)

david=#


david=# select pg_size_pretty(pg_relation_size('idx_join_date_test'));
 pg_size_pretty
----------------
MB
(1 row)

david=#

3.5 查看指定表中所有索引大小


david=# select pg_indexes_size('test');                 
 pg_indexes_size
-----------------
(1 row)

david=# select pg_size_pretty(pg_indexes_size('test'));
 pg_size_pretty
----------------
MB
(1 row)

david=#

idx_test 和idx_join_date_test 两个索引大小加起来差不多等于上面pg_indexes_size() 查询出来的索引大小。

3.6 查看指定schema 里所有的索引大小,按从大到小的顺序排列。


david=# select * from pg_namespace;
      nspname       | nspowner |               nspacl               
--------------------+----------+-------------------------------------
 pg_toast           |       10 |
 pg_temp_1          |       10 |
 pg_toast_temp_1    |       10 |
 pg_catalog         |       10 | {postgres=UC/postgres,=U/postgres}
 information_schema |       10 | {postgres=UC/postgres,=U/postgres}
 public             |       10 | {postgres=UC/postgres,=UC/postgres}
(6 rows)

david=# select indexrelname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_indexes where schemaname='public' order by pg_relation_size(relid) desc;
         indexrelname          | pg_size_pretty
-------------------------------+----------------
 idx_join_date_test            | 91 MB
 idx_test                      | 91 MB
 testtable_idx                 | 1424 kB
 city_pkey                     | 256 kB
 city11                        | 256 kB
 countrylanguage_pkey          | 56 kB
 sale_pkey                     | 8192 bytes
 track_pkey                    | 8192 bytes
 tbl_partition_201211_joindate | 8192 bytes
 tbl_partition_201212_joindate | 8192 bytes
 tbl_partition_201301_joindate | 8192 bytes
 tbl_partition_201302_joindate | 8192 bytes
 tbl_partition_201303_joindate | 8192 bytes
 customer_pkey                 | 8192 bytes
 album_pkey                    | 8192 bytes
 item_pkey                     | 8192 bytes
 tbl_partition_201304_joindate | 8192 bytes
 tbl_partition_201307_joindate | 8192 bytes
 tbl_partition_201305_joindate | 0 bytes
 tbl_partition_201306_joindate | 0 bytes
(20 rows)

david=#

3.7 查看指定表大小


david=# select pg_relation_size('test');               
 pg_relation_size
------------------
(1 row)

david=# select pg_size_pretty(pg_relation_size('test'));
 pg_size_pretty
----------------
MB
(1 row)

david=#

使用pg_table_size() 函数查看


david=# select pg_table_size('test');                  
 pg_table_size
---------------
(1 row)

david=# select pg_size_pretty(pg_table_size('test'));  
 pg_size_pretty
----------------
MB
(1 row)

david=#

3.8 查看指定表的总大小


david=# select pg_total_relation_size('test');      
 pg_total_relation_size
------------------------
(1 row)

david=# select pg_size_pretty(pg_total_relation_size('test'));
 pg_size_pretty
----------------
MB
(1 row)

david=#

3.9 查看指定schema 里所有的表大小,按从大到小的顺序排列。


david=# select relname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_tables where schemaname='public' order by pg_relation_size(relid) desc;
            relname            | pg_size_pretty
-------------------------------+----------------
 test                          | 91 MB
 testtable                     | 1424 kB
 city                          | 256 kB
 countrylanguage               | 56 kB
 country                       | 40 kB
 testcount                     | 8192 bytes
 tbl_partition_201302          | 8192 bytes
 tbl_partition_201303          | 8192 bytes
 person                        | 8192 bytes
 customer                      | 8192 bytes
 american_state                | 8192 bytes
 tbl_david                     | 8192 bytes
 emp                           | 8192 bytes
 tbl_partition_201212          | 8192 bytes
 tbl_partition_201304          | 8192 bytes
 tbl_partition_error_join_date | 8192 bytes
 tbl_partition_201211          | 8192 bytes
 album                         | 8192 bytes
 tbl_partition_201307          | 8192 bytes
 tbl_xulie                     | 8192 bytes
 tbl_partition_201301          | 8192 bytes
 sale                          | 8192 bytes
 item                          | 8192 bytes
 track                         | 8192 bytes
 tbl_partition_201306          | 0 bytes
 tbl_partition                 | 0 bytes
 tbl_partition_201305          | 0 bytes
 person2                       | 0 bytes
(28 rows)

david=#

3.10 查看表空间大小


david=# select spcname from pg_tablespace;
  spcname  
------------
 pg_default
 pg_global
(2 rows)

david=# select pg_tablespace_size('pg_default');               
 pg_tablespace_size
--------------------
(1 row)

david=# select pg_size_pretty(pg_tablespace_size('pg_default'));
 pg_size_pretty
----------------
GB
(1 row)

david=#

另一种查看方法:


david=# select pg_tablespace_size('pg_default')/1024/1024 as "SIZE M";    
 SIZE M
--------
(1 row)

david=# select pg_tablespace_size('pg_default')/1024/1024/1024 as "SIZE G";
 SIZE G
--------
(1 row)

david=#

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