slony_logshipping

slony_logshipper Tool

slony_logshipper is a tool designed to help apply logs. It runs as a daemon and scans the archive directory for new .SQL files which it then applies to the target database. It can be run with three sorts of parameters:

Options

• Options, chosen from the following:

  • h

    display this help text and exit

  • v

    display program version and exit

  • q

    quiet mode

  • l

    cause running daemon to reopen its logfile

  • r

    cause running daemon to resume after error

  • t

    cause running daemon to enter smart shutdown mode

  • T

    cause running daemon to enter immediate shutdown mode

  • c

    destroy existing semaphore set and message queue (use with caution)

  • f

    stay in foreground (don't daemonize)

  • w

    enter smart shutdown mode immediately

• A specified log shipper configuration file

  This configuration file consists of the following specifications:

  • logfile = './offline_logs/logshipper.log';

    Where the log shipper will leave messages.

  • cluster name = 'T1';

    Cluster name

  • destination database = 'dbname=slony_test3';

    Optional conninfo for the destination database. If given, the log shipper will connect to this database, and apply logs to it.

  • archive dir = './offline_logs';

    The archive directory is required when running in "database-connected" mode to have a place to scan for missing (unapplied) archives.

  • destination dir = './offline_result';

    If specified, the log shipper will write the results of data massaging into result logfiles in this directory.

  • max archives = 3600;

    This fights eventual resource leakage; the daemon will enter "smart shutdown" mode automatically after processing this many archives.

  • ignore table "public"."history";

    One may filter out single tables from log shipped replication

  • ignore namespace "public";

    One may filter out entire namespaces from log shipped replication

  • rename namespace "public"."history" to "site_001"."history";

    One may rename specific tables.

  • rename namespace "public" to "site_001";

    One may rename entire namespaces.

  • post processing command = 'gzip -9 $inarchive';

    Pre- and post-processing commands are executed via system(3).

  An "@" as the first character causes the exit code to be ignored. Otherwise, a nonzero exit code is treated as an error and causes processing to abort.

  Pre- and post-processing commands have two further special variables defined:

  • $inarchive - indicating incoming archive filename

  • $outnarchive - indicating outgoing archive filename

• error command = ' ( echo "archive=$inarchive" echo "error messages:" echo "$errortext" ) | mail -s "Slony log shipping failed" postgres@localhost ';

  The error command indicates a command to execute upon encountering an error. All logging since the last successful completion of an archive is available in the $errortext variable.

  In the example shown, this sends an email to the DBAs upon encountering an error.

• Archive File Names

  Each filename is added to the SystemV Message queue for processing by a slony_logshipper process.