postgresql查看数据库、索引、表、表空间大小

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
----------------
4
(1 row)

david=# select pg_column_size(10000);
pg_column_size
----------------
4
(1 row)

david=# select pg_column_size('david');
pg_column_size
----------------
6
(1 row)

david=# select pg_column_size('hello,world');
pg_column_size
----------------
12
(1 row)

david=# select pg_column_size('2013-04-18 15:17:21.622885+08');
pg_column_size
----------------
30
(1 row)

david=# select pg_column_size('中国');
pg_column_size
----------------
7
(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
---------
1835008
(1 row)

david=#

查看david 数据库大小

david=# select pg_database_size('david');
pg_database_size
------------------
190534776
(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
----------------
182 MB
(1 row)

david=#

3.4 查看单索引大小

david=# select pg_relation_size('idx_test');
pg_relation_size
------------------
41238528
(1 row)

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

david=#

david=# select pg_size_pretty(pg_relation_size('idx_join_date_test'));
pg_size_pretty
----------------
39 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
-----------------
82477056
(1 row)

david=# select pg_size_pretty(pg_indexes_size('test'));
pg_size_pretty
----------------
79 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
------------------
95748096
(1 row)

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

david=#

使用pg_table_size() 函数查看

david=# select pg_table_size('test');
pg_table_size
---------------
95789056
(1 row)

david=# select pg_size_pretty(pg_table_size('test'));
pg_size_pretty
----------------
91 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
------------------------
178266112
(1 row)

david=# select pg_size_pretty(pg_total_relation_size('test'));
pg_size_pretty
----------------
170 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
--------------------
28381579760
(1 row)

david=# select pg_size_pretty(pg_tablespace_size('pg_default'));
pg_size_pretty
----------------
26 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
--------
27066
(1 row)

david=# select pg_tablespace_size('pg_default')/1024/1024/1024 as "SIZE G";
SIZE G
--------
26
(1 row)

david=#