Database Reference
In-Depth Information
How to do it...
The following general points should be followed, allowing at least a month for the complete
process to ensure that everything is tested, and everybody understands the implications:
F
Set up a new release of software on a new system
F
Take a standalone backup from main system, and build a test server. Test
applications extensively against the new release on the test system. When
everything works and performs correctly, then:
Set up a connection pooler to main database (may have already)
Set up replication using Londiste or Slony to the new system, as described
previously
Re-test application extensively against the new release on live data, then
when ready for final cut-over we can:
F
Prepare a new connection pool config to point at the new system
F
Pause the connection pool
F
Switchover to the new system
F
Point the connection pool to the new system, and reload
How it works...
Slony and Londiste both work against multiple releases of PostgreSQL, so you can be sure
that cross-release replication works and works well. The preceding recipe allows for online
upgrade with zero data loss, because of the use of the clean switchover process. There's no
need for lengthy downtime during the upgrade, and there's much reduced risk in comparison
with an in-place upgrade. It works best with new hardware, and is a good way to upgrade the
hardware or change the disk layout at the same time. This is also very useful for changing
server encoding.
