I used pg_partman to create and drop partitions from my 2 postgres tables. Since there existed a foreign key relations among the tables, I couldn't drop the tables using partman(does not allow). However, I was able to detach the older partitioned tables(data older than 30 days) from the parent table. Now, in order to clean these tables, I need to get the names of the detached tables.

What sql query would help me achieve this ?

  • 1
    Since those tables are no longer attached to the partition parent, you need another way to identify them. Typically, you have naming pattern for partitions ... Commented Jun 25 at 0:44
  • Can we use pg_inherits and pg_class tables ? Commented Jun 25 at 11:30
  • Entries in those system catalogs are updated to look like regular tables. I don't know of anything still pointing to their partition past. Commented Jun 25 at 14:32
  • @ErwinBrandstetter The below query works but I want this to be reviewed and understand its correctness. Please have a look. The parent table's name is user_session_data : SELECT relname FROM pg_class c LEFT JOIN pg_inherits i ON c.oid = i.inhrelid WHERE i.inhrelid IS NULL AND relkind = 'r' AND relname LIKE 'user_session_data_%'; Commented Jun 25 at 17:45

1 Answer 1


Those tables are no longer attached to the partition parent, you need another way to identify them. Your comment indicates the naming pattern 'user_session_data_%'.
This returns all tables matching that pattern that are not partitions (any more):

SELECT relnamespace::regnamespace::text AS schema_name, relname AS table_name
FROM   pg_class c
WHERE  NOT relispartition  -- !
AND    relkind = 'r'
AND    relname LIKE 'user_session_data_%';  -- naming pattern for partitions

No need to join to pg_inherits. While Postgres maintains additional meta data for partitions (and legacy inheritance) there, looking at the flag pg_class.relispartition is simpler and more to the point. It's defined NOT NULL, so NOT relispartition can't fail for null values.

I also output the schema name to avoid possible confusion with other schemas. Alternatively, filter for the schema instead. Like:

AND   relnamespace = 'public'::regnamespace  -- your schema name here

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