bulk_loader.py [switches] config.ini
bulk_loader is PgQ consumer that reads url encoded records from source queue and writes them into tables according to configuration file. It is targeted to slow databases that cannot handle applying each row as separate statement. Originally written for BizgresMPP/greenplumDB which have very high per-statement overhead, but can also be used to load regular PostgreSQL database that cannot manage regular replication.
Behaviour properties: - reads urlencoded "logutriga" records. - does not do partitioning, but allows optionally redirect table events. - does not keep event order. - always loads data with COPY, either directly to main table (INSERTs) or to temp tables (UPDATE/COPY) then applies from there.
Events are usually procuded by pgq.logutriga(). Logutriga adds all the data of the record into the event (also in case of updates and deletes).
Basic bulk_loader setup and usage can be summarized by the following steps:
- 1. pgq and logutriga must be installed in source databases. See pgqadm man page for details. target database must also have pgq_ext schema.
- 2. edit a bulk_loader configuration file, say bulk_loader_sample.ini
create source queue
$ pgqadm.py ticker.ini create <queue>
Tune source queue to have big batches:
$ pgqadm.py ticker.ini config <queue> ticker_max_count="10000" ticker_max_lag="10 minutes" ticker_idle_period="10 minutes"
- 5. create target database and tables in it.
launch bulk_loader in daemon mode
$ bulk_loader.py -d bulk_loader_sample.ini
- 7. start producing events (create logutriga trggers on tables) CREATE OR REPLACE TRIGGER trig_bulk_replica AFTER INSERT OR UPDATE ON some_table FOR EACH ROW EXECUTE PROCEDURE pgq.logutriga(<queue>)
Common configuration parameters
- 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.
- Location for pid file. If not given, script is disallowed to daemonize.
- Location for log file.
- If continuisly running process, how long to sleep after each work loop, in seconds. Default: 1.
- Close and reconnect older database connections.
- Number of log files to keep. Default: 3
- Max size for one log file. File is rotated if max size is reached. Default: 10485760 (10M)
- 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
- Queue name to attach to. No default.
- Consumers ID to use when registering. Default: %(job_name)s
Config options specific to bulk_loader
- Connect string for source database where the queue resides.
- Connect string for target database where the tables should be created.
- Optional parameter for table redirection. Contains comma-separated list of <oldname>:<newname> pairs. Eg: oldtable1:newtable1, oldtable2:newtable2.
- Optional parameter for load method selection. Available options:
- UPDATE as UPDATE from temp table. This is default.
- UPDATE as DELETE+COPY from temp table.
- merge INSERTs with UPDATEs, then do DELETE+COPY from temp table.
LOGUTRIGA EVENT FORMAT
PgQ trigger function pgq.logutriga() sends table change event into queue in following format:
(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
- 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=
- Fully qualified table name.
COMMAND LINE SWITCHES
Following switches are common to all skytools.DBScript-based Python programs.
- show help message and exit
- make program silent
- make program more verbose
- 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.
- reload config (send SIGHUP)
- stop program safely (send SIGINT)
- kill program immidiately (send SIGTERM)