转载:PostgreSQL 查看数据库，索引，表，表空间大小

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转载：http://www.cnblogs.com/mchina/archive/2013/04/19/3028573.html

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)bigintpg_relation_size(..., 'main')的缩写pg_size_pretty(bigint)textConverts a size in bytes expressed as a 64-bit integer into a human-readable format with size unitspg_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=#