NAME
table_dispatcher - PgQ consumer that is used to write source records
into partitoned table.
SYNOPSIS
table_dispatcher.py [switches] config.ini
DESCRIPTION
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.
QUICK-START
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
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.
use_skylog
foo.
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;
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)
LOGUTRIGA EVENT FORMAT
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.
09/22/2008