Django needs the following parameters for its database connections:

If these parameters already have the correct values, Django won't set them for every new connection, which improves performance slightly. You can configure them directly in postgresql.conf or more conveniently per database user with ALTER ROLE.

Django will work just fine without this optimization, but each new connection will do some additional queries to set these parameters.

Like PostgreSQL itself, Django defaults to the READ COMMITTED isolation level. If you need a higher isolation level such as REPEATABLE READ or SERIALIZABLE, set it in the OPTIONS part of your database configuration in DATABASES:

import psycopg2.extensions 
 
DATABASES = { 
    # ... 
    'OPTIONS': { 
        'isolation_level': psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE, 
    }, 
} 

Under higher isolation levels, your application should be prepared to handle exceptions raised on serialization failures. This option is designed for advanced uses.

When specifying db_index=True on your model fields, Django typically outputs a single CREATE INDEX statement. However, if the database type for the field is either varchar or text (for example, used by CharField, FileField, and TextField), then Django will create an additional index that uses an appropriate PostgreSQL operator class for the column. The extra index is necessary to correctly perform lookups that use the LIKE operator in their SQL, as is done with the contains and startswith lookup types.