Postgresql: Check if Schema Exists?

I need to create, manage and drop schemas on the fly. If I go to create a schema that already exists, I want to (conditionally, via external means) drop and recreate it as specified. How can I check for the existence of said schema on my Postgres 9 server?

Currently, I'm doing this:

select exists (select * from pg_catalog.pg_namespace where nspname = 'schemaname');

but I feel like there's probably another way... is this the "proper" way to query Postgres for the existence of a particular schema?

The following query will tell you whether a schema exists.

SELECT schema_name FROM information_schema.schemata WHERE schema_name = 'name';

If you are a total purist or you want to gain some milisecs. I recommend you to make use of postgres native system catalog. One can avoid then nested loop which is caused by calling pg_catalog anyway...

SELECT EXISTS(SELECT 1 FROM information_schema.schemata 
              WHERE schema_name = 'name');

querying information_schema

If you querying pg_namespace directly:

SELECT EXISTS(SELECT 1 FROM pg_namespace WHERE nspname = 'name');

Planer's work is much simpler:

enter image description here

So your own solution was the best.

Somewhat related and perhaps of interest to others looking for conditional schema creation. I found myself using code like this in some of my creation scripts:

DO $$
BEGIN

    IF NOT EXISTS(
        SELECT schema_name
          FROM information_schema.schemata
          WHERE schema_name = 'pgcrypto'
      )
    THEN
      EXECUTE 'CREATE SCHEMA pgcrypto';
    END IF;

END
$$;

This can be one of the approaches. Drop the schema first and then create it.

IF EXISTS:
Do not throw an error if the schema does not exist. A notice is issued in this case.

So,

DROP SCHEMA IF EXISTS schema_Name
Create SCHEMA schema_Name

Postgresql: Check if Schema Exists?

Related

Recent Posts