Slony_logshippping daemon
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:
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Options, chosen from the following:
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\*(T<h\*(T>
display this help text and exit
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\*(T<v\*(T>
display program version and exit
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\*(T<q\*(T>
quiet mode
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\*(T<l\*(T>
cause running daemon to reopen its logfile
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\*(T<r\*(T>
cause running daemon to resume after error
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\*(T<t\*(T>
cause running daemon to enter smart shutdown mode
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\*(T<T\*(T>
cause running daemon to enter immediate shutdown mode
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\*(T<c\*(T>
destroy existing semaphore set and message queue (use with caution)
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\*(T<f\*(T>
stay in foreground (don't daemonize)
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\*(T<w\*(T>
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 \(oqdatabase-connected\(cq 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 \(oqsmart shutdown\(cq 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 \*(T<system(3)\*(T>.
An \(oq@\(cq 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.