postgres db files - which file represents the specific table/index?

Question

when i go into sql-8.2/base/ to check how much space does my table take, there are plenty of files named by a number. how can i find the specific file which sto

Answer 1

Each directory represents a database (created via create database). The number is the oid of the database. To see the oid and its name, run the following statement:

select oid, datname
from pg_database;

Inside each directory each file corresponds to the an entry in pg_class where the oid matches the number of the file in the directory:

You can see the oids and to which relation they relate by running the statement:

select cl.relfilenode, nsp.nspname as schema_name, cl.relname, cl.relkind
from pg_class cl
  join pg_namespace nsp on cl.relnamespace = nsp.oid;

You might also want to check out the manual

• Determining Disk Usage
• Database File Layout
• System catalogs

Btw: if you are really still running 8.2 you should upgrade as soon as possible.

Answer 2

select pg_relation_filepath('OID or name of a table, index, sequence, or toast table');

For example:

select pg_relation_filepath('flush_history');
Returns base/83780/153211 which you will find in your data directory.

http://www.postgresql.org/docs/current/static/functions-admin.html

Answer 3

To check how much space the table takes use:

SELECT pg_size_pretty(pg_total_relation_size('table_name_here'))

It will give you the size of a table with its indexes and "toast" tables. Details here.