PostgreSQL provides multiple system management functions to view tables, indexes, tablespaces and database sizes. Here is a detailed introduction.
2. Database object size function
| Function name | Return type | describe |
| pg_column_size(any) | int | Stores the number of bytes required for a specified value (maybe compressed) |
| pg_database_size(oid) | bigint | Specify the disk space used by the database for the OID |
| pg_database_size(name) | bigint | The disk space used by the database with the specified name |
| pg_indexes_size(regclass) | bigint | Total disk space used for the table index associated with the specified table OID or table name |
| pg_relation_size(relation regclass, fork text) | bigint | Specify the table or index of OID or name, by specifying fork('main', The disk space used by 'fsm' or 'vm') |
| pg_relation_size(relation regclass) | bigint | abbreviation of pg_relation_size(..., 'main') |
| 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 | Convert bytes to a human-readable unit of size |
| pg_table_size(regclass) | bigint | Specify the disk space used by the table OID or table name, remove the index (but contains TOAST, free space maps, and visual maps) |
| pg_tablespace_size(oid) | bigint | Specify the disk space used by the tablespace of the OID |
| pg_tablespace_size(name) | bigint | The disk space used by the tablespace with the specified name |
| pg_total_relation_size(regclass) | bigint | Specifies the total disk space used by the table OID or table name, including all indexes andTOASTdata |
3. Example explanation
3.1 View the number of bytes required to store a specified value
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('China');
pg_column_size
----------------
(1 row)
david=#
3.2 Check the database size
View original data
david=# \d test
Table ""
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=#
View the david database size
david=# select pg_database_size('david');
pg_database_size
------------------
(1 row)
david=#
View all database sizes
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=#
The results found in this way look too long and are not easy to read.
3.3 Display size in a humanized way
david=# select pg_size_pretty(pg_database_size('david'));
pg_size_pretty
----------------
MB
(1 row)
david=#
3.4 View single index size
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=#
david=# select pg_size_pretty(pg_relation_size('idx_join_date_test'));
pg_size_pretty
----------------
MB
(1 row)
david=#
3.5 View all index sizes in the specified table
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=#
The sum of the two index sizes of idx_test and idx_join_date_test are almost equal to the index size queried by pg_indexes_size() above.
3.6 View all index sizes in the specified schema and arrange them in order from large to small.
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 View the specified table size
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=#
Use the pg_table_size() function to view
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 View the total size of the specified table
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 View all table sizes in the specified schema and arrange them in order from large to small.
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 Check the tablespace size
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=#
Another way to view:
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=#