QUEUE_SPLITTER(1)														 QUEUE_SPLITTER(1)

NAME

       queue_splitter - PgQ consumer that transports events from one queue into several target queues

SYNOPSIS

       queue_splitter.py [switches] config.ini

DESCRIPTION

       queue_spliter is PgQ consumer that transports events from source queue into several target queues. ev_extra1 field in each event shows into
       which target queue it must go. (pgq.logutriga() puts there the table name.)

       One use case is to move events from OLTP database to batch processing server. By using queue spliter it is possible to move all kinds of
       events for batch processing with one consumer thus keeping OLTP database less crowded.

QUICK-START
       Basic queue_splitter setup and usage can be summarized by the following steps:

	1. pgq must be installed both in source and target databases. See pgqadm man page for details. Target database must also have pgq_ext
	   schema installed.

	2. edit a queue_splitter configuration file, say queue_splitter_sourcedb_sourceq_targetdb.ini

	3. create source and target queues

	       $ pgqadm.py ticker.ini create <queue>

	4. launch queue splitter in daemon mode

	       $ queue_splitter.py queue_splitter_sourcedb_sourceq_targetdb.ini -d

	5. start producing and consuming events

CONFIG

   Common configuration parameters
       job_name
	   Name for particulat job the script does. Script will log under this name to logdb/logserver. The name is also used as default for PgQ
	   consumer name. It should be unique.

       pidfile
	   Location for pid file. If not given, script is disallowed to daemonize.

       logfile
	   Location for log file.

       loop_delay
	   If continuisly running process, how long to sleep after each work loop, in seconds. Default: 1.

       connection_lifetime
	   Close and reconnect older database connections.

       log_count
	   Number of log files to keep. Default: 3

       log_size
	   Max size for one log file. File is rotated if max size is reached. Default: 10485760 (10M)

       use_skylog
	   If set, search for [./skylog.ini, ~/.skylog.ini, /etc/skylog.ini]. If found then the file is used as config file for Pythons logging
	   module. It allows setting up fully customizable logging setup.

   Common PgQ consumer parameters
       pgq_queue_name
	   Queue name to attach to. No default.

       pgq_consumer_id
	   Consumers ID to use when registering. Default: %(job_name)s

   queue_splitter parameters
       src_db
	   Source database.

       dst_db
	   Target database.

   Example config file
	   [queue_splitter]
	   job_name	   = queue_spliter_sourcedb_sourceq_targetdb

	   src_db	   = dbname=sourcedb
	   dst_db	   = dbname=targetdb

	   pgq_queue_name  = sourceq

	   logfile	   = ~/log/%(job_name)s.log
	   pidfile	   = ~/pid/%(job_name)s.pid

COMMAND LINE SWITCHES

       Following switches are common to all skytools.DBScript-based Python programs.

       -h, --help
	   show help message and exit

       -q, --quiet
	   make program silent

       -v, --verbose
	   make program more verbose

       -d, --daemon
	   make program go background

       Following switches are used to control already running process. The pidfile is read from config then signal is sent to process id specified
       there.

       -r, --reload
	   reload config (send SIGHUP)

       -s, --stop
	   stop program safely (send SIGINT)

       -k, --kill
	   kill program immidiately (send SIGTERM)

USECASE

       How to to process events created in secondary database with several queues but have only one queue in primary database. This also shows how
       to insert events into queues with regular SQL easily.

	   CREATE SCHEMA queue;
	   CREATE TABLE queue.event1 (
		-- this should correspond to event internal structure
		-- here you can put checks that correct data is put into queue
		id int4,
		name text,
		-- not needed, but good to have:
		primary key (id)
	   );
	   -- put data into queue in urlencoded format, skip actual insert
	   CREATE TRIGGER redirect_queue1_trg BEFORE INSERT ON queue.event1
	   FOR EACH ROW EXECUTE PROCEDURE pgq.logutriga('singlequeue', 'SKIP');
	   -- repeat the above for event2

	   -- now the data can be inserted:
	   INSERT INTO queue.event1 (id, name) VALUES (1, 'user');

       If the queue_splitter is put on "singlequeue", it spreads the event on target to queues named "queue.event1", "queue.event2", etc. This
       keeps PgQ load on primary database minimal both CPU-wise and maintenance-wise.

								    03/13/2012							 QUEUE_SPLITTER(1)