Pgq

ActiveRecord extension to work with PgQ Skytools for PostgreSQL.

Details about PgQ:

Install

  1. Install skytools (pgfoundry.org/projects/skytools)

  2. Add require ‘pgq’ to Rakefile to enable pgq rake tasks

  3. Create PgQ config in config/pgq/#RAILS_ENV.ini or run

rake pgq:gen_config

to generate PgQ config from your database.yml. If there a development_slave section in your database.yml, then londiste config will be generated/

  1. Install PgQ schema in your DB

    rake pgq:install

  2. If you need an londiste replication, run

rake londiste:provider:install rake londiste:subscriber:install

rake londiste:update

to install londiste on provider and subscriber (slave) and add tables to replication.

  1. Run

rake pgq:start

to start PgQ ticker - process, that maintain PgQ queue. Without this queue will not work. Also run

rake londiste:start

to start Londiste replication.

Run

rake londiste:stat

to see replication status.

Example

See examples folder for PgqTest and PgqRunner classes.

To start using pgq add queue and subscription to PgQ (good place for this is migration).

ActiveRecord::Base.pgq_create_queue(PgqTest::QUEUE_NAME) ActiveRecord::Base.pgq_register_consumer(PgqTest::QUEUE_NAME, PgqRunner::PGQ_CONSUMER)

After this you can run consumers:

runner = PgqRunner.new :queues => [PgqTest::QUEUE_NAME], :watch_file => ‘tmp/stop.txt’

Because of PgQ process events in batches, next time you run consumer after Ctrl-C, events starts to process from the begining of the batch. Therefore when consumer see watch_file, it mark all events to retry and finish current batch.

runner.run

In other console call PgqTest.add_event 10 and return to first console. If you see 100 - all is ok.

Failed events mark as failed, see PgQ docs for more information.

Sorry for my English ;-)

Copyright © 2009 Andrey Stikheev, Ivan Evtukhovich, released under the MIT license