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table_dispatcher: PgQ consumer that is used to write source records into partitoned table.

table_dispatcher - PgQ consumer that is used to write source records into partitoned table.
table_dispatcher.py [switches] config.ini


table_dispatcher is PgQ consumer that reads url encoded records from source queue and writes them into partitioned tables according to configuration file. Used to partiton data. For example change log's that need to kept online only shortly can be written to daily tables and then dropped as they become irrelevant. Also allows to select which columns have to be written into target database Creates target tables according to configuration file as needed.


Basic table_dispatcher setup and usage can be summarized by the following steps: 1. PgQ must be installed in source database. See pgqadm man page for details. Target database must have pgq_ext schema installed. 2. edit a table_dispatcher configuration file, say table_dispatcher_sample.ini 3. create source queue $ pgqadm.py ticker.ini create <queue> 4. launch table dispatcher in daemon mode $ table_dispatcher.py table_dispatcher_sample.ini -d 5. start producing events


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 table_dispatcher parameters src_db Source database. dst_db Target database. dest_table Where to put data. when partitioning, will be used as base name part_field date field with will be used for partitioning. part_template SQL code used to create partition tables. Various magic replacements are done there: _PKEY comma separated list of primery key columns. _PARENT schema-qualified parent table name. _DEST_TABLE schema-qualified partition table. _SCHEMA_TABLE same as DEST_TABLE but dots replaced with "_", to allow use as index names. Example config [table_dispatcher] job_name = table_dispatcher_source_table_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 # where to put data. when partitioning, will be used as base name dest_table = orders # names of the fields that must be read from source records fields = id, order_date, customer_name # date field with will be used for partitioning part_field = order_date # template used for creating partition tables part_template = create table _DEST_TABLE () inherits (orders); alter table only _DEST_TABLE add constraint _DEST_TABLE_pkey primary key (id); grant select on _DEST_TABLE to group reporting;


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)
PgQ trigger function pgq.logutriga() sends table change event into queue in following format: ev_type (op || ":" || pkey_fields). Where op is either "I", "U" or "D", corresponging to insert, update or delete. And pkey_fields is comma-separated list of primary key fields for table. Operation type is always present but pkey_fields list can be empty, if table has no primary keys. Example: I:col1,col2 ev_data Urlencoded record of data. It uses db-specific urlecoding where existence of = is meaningful - missing = means NULL, present = means literal value. Example: id=3&name=str&nullvalue&emptyvalue= ev_extra1 Fully qualified table name. 11/10/2010 TABLE_DISPATCHER(1)

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