1、应用场景
场景1：查看数据库占用空间大小
SELECT pg_size_pretty(pg_database_size('database_name'));
场景2：查看每张表占用空间大小
SELECTtable_schema || '.' || table_name AS table,#仅表数据pg_size_pretty(pg_relation_size(table_schema || '.' || table_name)) AS size#表数据+索引数据#pg_size_pretty(pg_total_relation_size(table_schema || '.' || table_name)) AS size
FROM information_schema.tables
WHERE table_schema = 'public'
ORDER BYpg_relation_size(table_schema || '.' || table_name) DESC;#pg_total_relation_size(table_schema || '.' || table_name) DESC;
查看特定表占用大小， 可用：
#仅表数据
SELECT pg_size_pretty(pg_relation_size('schemal_test.table_test'));
#表数据+索引数据
SELECT pg_size_pretty(pg_total_relation_size('schemal_test.table_test'));
2、PostgreSQL 空间大小知多少
表空间(Table Space)
#查找 postgresql 表空间大小
SELECT pg_size_pretty (pg_tablespace_size ('tablespace_name'));#所有表空间的名称和大小
SELECT spcname, pg_size_pretty(pg_tablespace_size(spcname)) as size from pg_tablespace;
数据库(Database)
#查找单个 postgresql 数据库大小
SELECT pg_size_pretty(pg_database_size('db_name'));#所有数据库的总大小，以易读的格式显示
SELECT pg_size_pretty(SUM(pg_database_size(datname))) FROM pg_database;#查看所有数据库的列表及其大小（以 GB 为单位），降序
SELECTpg_database.datname as db_name,pg_database_size(pg_database.datname)/1024/1024/1024 as db_size
FROM pg_database ORDER by db_size DESC;#或 pg_size_pretty用修饰大小
SELECTpg_database.datname as db_name,pg_size_pretty(pg_database_size(pg_database.datname)) as db_size
FROM pg_database ORDER by pg_database_size(pg_database.datname) DESC;#查看所有数据库的名称、所有者以及它们各自的大小
SELECT db.datname AS db_name,pg_catalog.pg_get_userbyid(db.datdba) AS owner,CASEWHEN pg_catalog.has_database_privilege(db.datname, 'CONNECT') THENpg_catalog.pg_size_pretty(pg_catalog.pg_database_size(db.datname))ELSE 'No Access'END AS size
FROM pg_catalog.pg_database db
ORDER BY CASEWHEN pg_catalog.has_database_privilege(db.datname, 'CONNECT') THENpg_catalog.pg_database_size(db.datname)END;
模式(Schema)
#当前模式或任何模式中所有表的大小、表相关对象的大小以及总表大小
SELECT stats.relname as table_name,pg_size_pretty(pg_relation_size(statios.relid)) as table_size,pg_size_pretty(pg_total_relation_size(statios.relid) - pg_relation_size(statios.relid)) as external_size,pg_size_pretty(pg_total_relation_size(statios.relid)) as total_table_size,stats.n_live_tup as live_rows
FROM pg_catalog.pg_statio_user_tables as statios
JOIN pg_stat_user_tables as stats
USING (relname)
WHERE stats.schemaname = 'schema_name' -- 替换成模式名称
UNION ALL
SELECT 'TOTAL' as table_name,pg_size_pretty(sum(pg_relation_size(statios.relid))) AS table_size,pg_size_pretty(sum(pg_total_relation_size(statios.relid) - pg_relation_size(statios.relid))) AS external_size,pg_size_pretty(sum(pg_total_relation_size(statios.relid))) AS total_table_size,sum(stats.n_live_tup) AS live_rows
FROM pg_catalog.pg_statio_user_tables AS statios
JOIN pg_stat_user_tables AS stats
USING (relname)
WHERE stats.schemaname = 'schema_name' -- 替换成模式名称
ORDER BY live_rows ASC;
表(Table-Relation)
#查看postgresql 数据库的单个表大小-不包括依赖项大小：
SELECT pg_size_pretty(pg_relation_size('schema_test.table_name'));
#SELECT pg_size_pretty(pg_relation_size('table_name'));#查看postgresql 数据库的单个表大小-包括依赖项大小：
SELECT pg_size_pretty(pg_total_relation_size('schema_test.table_name'));
#SELECT pg_size_pretty(pg_total_relation_size('table_name'));#查找当前数据库中每张表大小，包含索引
SELECT table_schema || '.' || table_name as table_name, pg_size_pretty(pg_total_relation_size('"' || table_schema || '"."' || table_name || '"')) as table_size
FROM information_schema.tables
ORDER BY pg_total_relation_size('"' || table_schema || '"."' || table_name || '"') DESC#查找当前数据库中每张表和索引大小，包含索引
SELECTtable_name,pg_size_pretty(pg_table_size(table_name)) as table_size,pg_size_pretty(pg_indexes_size(table_name)) as index_size, pg_size_pretty(pg_total_relation_size(table_name)) as total_size
FROM (select ('"' || table_schema || '"."' || table_name || '"') as table_name FROM information_schema.tables) as tables
ORDER BY 4 DESC#查看表大小以及依赖项大小
SELECT schemaname as schema_name,relname as table_name,pg_size_pretty(pg_total_relation_size(relid)) as table_size,pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) as external_size
FROM pg_catalog.pg_statio_user_tables
ORDER BY pg_total_relation_size(relid) DESC;#查看所有表的行数
select relname as table_name, reltuples as rows from pg_class where relkind = ‘r’ order by rowCounts desc
索引(Index-Relation)
#postgresql数据库的单个索引大小：
SELECT pg_size_pretty(pg_indexes_size('index_name'));#列出数据库中每个索引的大小
SELECT indexrelname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_indexes;
列(Column)
#PostgreSQL 列值大小, 要查找存储特定值需要多少空间，可以使用 pg_column_size() 函数，例如：
select pg_column_size(5::smallint);
select pg_column_size(5::int);
select pg_column_size(5::bigint);#获取OID
select * from pg_class where relname='table_name';
select oid, datname from pg_database;#查看文件地址
select pg_relation_filepath('table_name');
函数说明
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
把以字节计算的数值转换成一个人类易读的单位
pg_size_pretty(numeric)
text
把以字节计算的数值转换成一个人类易读的单位
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
oid获取
#获取数据表的OID
select oid,relname from pg_class where relname='table_name';
#获取数据库的OID
select oid, datname from pg_database;
#获取数据表的文件路径
select pg_relation_filepath('table_name');