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Slony-I

Slony-I is a "master to multiple slaves" replication system with cascading and failover.

The big picture for the development of Slony-I is a master-slave system that includes all features and capabilities needed to replicate large databases to a reasonably limited number of slave systems.

Slony-I is a system for data centers and backup sites, where the normal mode of operation is that all nodes are available.

A fairly extensive "admin guide" comprising material in the CVS tree may be found here There is also a local copy here

The original design document is available here; see also initial description of implementation..

Upgrading Slony-I

Beginning with version 1.0.5 the slon replication engine refuses to work against any database that does not have the stored procedures for the same version loaded or where the shared object containing the C language support functions and the log trigger does not match the version number.

This means that the Slony installation on all nodes in a cluster must be upgraded at once.

The proper upgrade procedure is this:

1. Stop the slon replication engine on all nodes.
2. Install the new Slony version on all nodes.
3. Execute a slonik script containing the command

       update functions (id = );
   

   for every node in the cluster.
4. Start all slon replication engines.

For more details, see also Upgrading Slony-I .

Libpq requirements

The multithreaded replication engine requires the libpq client library to be compiled with --enable-thread-safety on certain operating systems. Known are thus far Solaris and AIX. Other operating systems are known to not require this (Linux-X86, FreeBSD-X86, FreeBSD-Alpha, OpenBSD-Sparc64 and OSX). The configuration script is broken with respect to the --enable-thread-safety switch for Solaris. Please apply this patch, configure and recompile libpq: threadsafe-libpq-742.diff.gz.

RPMs

RPM files for some versions of Red Hat Linux are available here , including SRPM (Source RPM) files that may be helpful if you wish to generate RPM files for distributions not yet supported.

This project is released under the Berkeley/BSD license.