Activating and Deactivating GPORCA

By default, LightDB-A Database uses GPORCA instead of the Postgres Planner. Server configuration parameters activate or deactivate GPORCA.

Although GPORCA is on by default, you can configure GPORCA usage at the system, database, session, or query level using the optimizer parameter. Refer to one of the following sections if you want to change the default behavior:

Note You can deactivate the ability to activate or deactivate GPORCA with the server configuration parameter optimizer_control. For information about the server configuration parameters, see the LightDB-A Database Reference Guide.

Parent topic: About GPORCA

Enabling GPORCA for a System

Set the server configuration parameter optimizer for the LightDB-A Database system.

  1. Log into the LightDB-A Database coordinator host as gpadmin, the LightDB-A Database administrator.

  2. Set the values of the server configuration parameters. These LightDB-A Database gpconfig utility commands sets the value of the parameters to on:

    $ gpconfig -c optimizer -v on --masteronly

  3. Restart LightDB-A Database. This LightDB-A Database gpstop utility command reloads the postgresql.conf files of the coordinator and segments without shutting down LightDB-A Database.

    gpstop -u

Enabling GPORCA for a Database

Set the server configuration parameter optimizer for individual LightDB-A databases with the ALTER DATABASE command. For example, this command enables GPORCA for the database test_db.

> ALTER DATABASE test_db SET OPTIMIZER = ON ;

Enabling GPORCA for a Session or a Query

You can use the SET command to set optimizer server configuration parameter for a session. For example, after you use the psql utility to connect to LightDB-A Database, this SET command enables GPORCA:

> set optimizer = on ;

To set the parameter for a specific query, include the SET command prior to running the query.