PostgreSQL 查看數據庫，索引，表，表空間大小的示例代碼
2020-03-12 23:54:59
供稿：網友
PostgreSQL 提供了多個系統管理函數來查看表，索引，表空間及數據庫的大小，下面詳細介紹一下
一、簡介
PostgreSQL 提供了多個系統管理函數來查看表，索引，表空間及數據庫的大小，下面詳細介紹一下。
二、數據庫對象尺寸函數
函數名 返回類型 描述
pg_column_size(any) int 存儲一個指定的數值需要的字節數（可能壓縮過）
pg_database_size(oid) bigint 指定OID的數據庫使用的磁盤空間
pg_database_size(name) bigint 指定名稱的數據庫使用的磁盤空間
pg_indexes_size(regclass) bigint 關聯指定表OID或表名的表索引的使用總磁盤空間
pg_relation_size(relation regclass, fork text) bigint 指定OID或名的表或索引，通過指定fork('main','fsm' 或'vm')所使用的磁盤空間
pg_relation_size(relation regclass) bigint pg_relation_size(..., 'main')的縮寫
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 把以字節計算的數值轉換成一個人類易讀的尺寸單位
pg_table_size(regclass) bigint 指定表OID或表名的表使用的磁盤空間，除去索引（但是包含TOAST，自由空間映射和可視映射）
pg_tablespace_size(oid) bigint 指定OID的表空間使用的磁盤空間
pg_tablespace_size(name) bigint 指定名稱的表空間使用的磁盤空間
pg_total_relation_size(regclass) bigint 指定表OID或表名使用的總磁盤空間，包括所有索引和TOAST數據
三、實例講解
3.1 查看存儲一個指定的數值需要的字節數
復制代碼代碼如下:
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('中國');
pg_column_size
----------------
(1 row)
david=#
3.2 查看數據庫大小
查看原始數據
復制代碼代碼如下:
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;
count
---------
(1 row)
david=#
查看david 數據庫大小
復制代碼代碼如下:
david=# select pg_database_size('david');
pg_database_size
------------------
(1 row)
david=#
查看所有數據庫大小
復制代碼代碼如下:
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=#
這樣查出來的結果，看上去太長了，不太容易讀數。
3.3 以人性化的方式顯示大小
復制代碼代碼如下:
david=# select pg_size_pretty(pg_database_size('david'));
pg_size_pretty
----------------
MB
(1 row)
david=#
3.4 查看單索引大小
復制代碼代碼如下:
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=#
復制代碼代碼如下:
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
復制代碼代碼如下:
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 兩個索引大小加起來差不多等于上面pg_indexes_size() 查詢出來的索引大小。
3.6 查看指定schema 里所有的索引大小，按從大到小的順序排列。
復制代碼代碼如下:
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;
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
復制代碼代碼如下:
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() 函數查看
復制代碼代碼如下:
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 查看指定表的總大小
復制代碼代碼如下:
david=# select pg_total_relation_size('test');
pg_total_relation_size
------------------------
(1 row)
david=# select pg_size_pretty(pg_total_relation_size('test'));
pg_size_pretty
----------------
MB
(1 row)
david=#
3.9 查看指定schema 里所有的表大小，按從大到小的順序排列。
復制代碼代碼如下:
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 查看表空間大小
復制代碼代碼如下:
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=#
另一種查看方法：
復制代碼代碼如下:
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";
SIZE G
--------
(1 row)
david=#
