slony_logshipping

NAME

slony_logshipping - slony_logshippping daemon

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

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Options, chosen from the following:
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h

display this help text and exit

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v

display program version and exit

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q

quiet mode

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l

cause running daemon to reopen its logfile

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r

cause running daemon to resume after error

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t

cause running daemon to enter smart shutdown mode

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T

cause running daemon to enter immediate shutdown mode

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c

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

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f

stay in foreground (don’t daemonize)

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w

enter smart shutdown mode immediately

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A specified log shipper configuration file

This configuration file consists of the following specifications:
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logfile = ’./offline_logs/logshipper.log’;

Where the log shipper will leave messages.

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cluster name = ’T1’;

Cluster name

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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.

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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.

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destination dir = ’./offline_result’;

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

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max archives = 3600;

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

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ignore table "public"."history";

One may filter out single tables from log shipped replication

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ignore namespace "public";

One may filter out entire namespaces from log shipped replication

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

One may rename specific tables.

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rename namespace "public" to "site_001";

One may rename entire namespaces.

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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:

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$inarchive - indicating incoming archive filename

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$outnarchive - indicating outgoing archive filename

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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.

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Archive File Names

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