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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
三、实例讲解 3.1 查看存储一个指定的数值需要的字节数 复制代码 代码如下: david=# select pg_column_size(1); pg_column_size ---------------- (1 row) david=# select pg_column_size(10000); david=# select pg_column_size('david'); david=# select pg_column_size('hello,world'); david=# select pg_column_size('2013-04-18 15:17:21.622885+08'); david=# select pg_column_size('中国'); david=# 3.2 查看数据库大小 查看原始数据 复制代码 代码如下: 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; david=# 查看david 数据库大小 复制代码 代码如下: david=# select pg_database_size('david'); pg_database_size ------------------ (1 row) david=# 查看所有数据库大小 复制代码 代码如下: 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 复制代码 代码如下: 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 复制代码 代码如下: david=# select pg_relation_size('idx_test'); pg_relation_size ------------------ (1 row) david=# select pg_size_pretty(pg_relation_size('idx_test')); david=# 复制代码 代码如下: 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 复制代码 代码如下: david=# select pg_indexes_size('test'); pg_indexes_size ----------------- (1 row) david=# select pg_size_pretty(pg_indexes_size('test')); 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。 复制代码 代码如下: 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; david=# 3.7 查看指定表大小 复制代码 代码如下: david=# select pg_relation_size('test'); pg_relation_size ------------------ (1 row) david=# select pg_size_pretty(pg_relation_size('test')); david=# 使用pg_table_size() 函数查看 复制代码 代码如下: david=# select pg_table_size('test'); pg_table_size --------------- (1 row) david=# select pg_size_pretty(pg_table_size('test')); david=# 3.8 查看指定表的总大小 复制代码 代码如下: david=# select pg_total_relation_size('test'); pg_total_relation_size ------------------------ (1 row) david=# select pg_size_pretty(pg_total_relation_size('test')); 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。 复制代码 代码如下: 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 复制代码 代码如下: david=# select spcname from pg_tablespace; spcname ------------ pg_default pg_global (2 rows) david=# select pg_tablespace_size('pg_default'); david=# select pg_size_pretty(pg_tablespace_size('pg_default')); david=# 另一种查看方法： 复制代码 代码如下: 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"; david=# |
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