postgresql list and order tables by size

Question

select table_name, pg_relation_size(quote_ident(table_name))
from information_schema.tables
where table_schema = 'public'
order by 2

This shows you the size of all tables in the schema public if you have multiple schemas, you might want to use:

select table_schema, table_name, pg_relation_size('"'||table_schema||'"."'||table_name||'"')
from information_schema.tables
order by 3

SQLFiddle example: http://sqlfiddle.com/#!15/13157/3

List of all object size functions in the manual.

This will show you the schema name, table name, size pretty and size (needed for sort).

SELECT
  schema_name,
  relname,
  pg_size_pretty(table_size) AS size,
  table_size

FROM (
       SELECT
         pg_catalog.pg_namespace.nspname           AS schema_name,
         relname,
         pg_relation_size(pg_catalog.pg_class.oid) AS table_size

       FROM pg_catalog.pg_class
         JOIN pg_catalog.pg_namespace ON relnamespace = pg_catalog.pg_namespace.oid
     ) t
WHERE schema_name NOT LIKE 'pg_%'
ORDER BY table_size DESC;

I build this based on the solutions from here list of schema with sizes (relative and absolute) in a PostgreSQL database

This will be more clear.

pg_size_pretty(<numeric_value>) - converts no.of bytes to human-readable format.

pg_database_size(<db_name>) - gets database size in bytes.

pg_total_relation_size(<relation_name>) - gets total size of table and its index in bytes.

pg_relation_size(<relation_name>) - gets relation (table/index) size in bytes.

pg_index_size(<relation_name>) - gets index size of the relation in bytes.

current_database() - gets the currently used database on which this query is being performed.

Query:

select current_database() as database,
       pg_size_pretty(total_database_size) as total_database_size,
       schema_name,
       table_name,
       pg_size_pretty(total_table_size) as total_table_size,
       pg_size_pretty(table_size) as table_size,
       pg_size_pretty(index_size) as index_size
       from ( select table_name,
                table_schema as schema_name,
                pg_database_size(current_database()) as total_database_size,
                pg_total_relation_size(table_name) as total_table_size,
                pg_relation_size(table_name) as table_size,
                pg_indexes_size(table_name) as index_size
                from information_schema.tables
                where table_schema=current_schema() and table_name like 'table_%'
                order by total_table_size
            ) as sizes;

Result:

 database  | total_database_size | schema_name | table_name | total_table_size | table_size | index_size
-----------+---------------------+-------------+------------+------------------+------------+------------
 vigneshdb | 1586 MB             | corpdata    | table_aaa  | 16 kB            | 0 bytes    | 8192 bytes
 vigneshdb | 1586 MB             | corpdata    | table_bbb  | 24 kB            | 0 bytes    | 16 kB
 vigneshdb | 1586 MB             | corpdata    | table_ccc  | 640 kB           | 112 kB     | 488 kB
 vigneshdb | 1586 MB             | corpdata    | table_ddd  | 9760 kB          | 3152 kB    | 6568 kB
 vigneshdb | 1586 MB             | corpdata    | table_eee  | 1120 MB          | 311 MB     | 808 MB

The humanized format is represent in bytes, kB, MB, GB, and TB.

bytes to kB - begins from 10240 bytes

bytes to MB - begins from 10485248 bytes = 10239.5 kB ~ 10 MB

bytes to GB - begins from 10736893952 bytes = 10239.5 MB ~ 10 BG

bytes to TB - begins from 10994579406848 bytes = 10239.5 GB ~ 10 TB

All unit conversions starts from 10 + <unit>.

For reference - Postgres Official Documentation

SELECT
   relname as "Table",
   pg_size_pretty(pg_total_relation_size(relid)) As "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;

taken from here https://wiki-bsse.ethz.ch/display/ITDOC/Check+size+of+tables+and+objects+in+PostgreSQL+database

I needed to find which tables use the most space.

Based on other answers, I used that query:

select table_name, pg_size_pretty( pg_relation_size(quote_ident(table_name)) )
from information_schema.tables
where table_schema = 'public'
order by pg_relation_size(quote_ident(table_name)) desc

I get the following result:

table_name              pg_size_pretty
--------------------------------------
trade_binance           96 GB
closs_v2_binance_stash  46 GB
closs_bitfinex_stash    5725 MB
trade_bitfinex          5112 MB
...
api_requests            0 bytes
trade_huobi             0 bytes

I should have bought a bigger SSD.