PostgreSQL 10 High Performance - Third Edition

Upgrades to PostgreSQL 8.3+ from earlier ones

The major internal changes to 8.3 make it impossible to upgrade from any earlier version past it without dumping the entire database and reloading it into the later one. This makes 8.3 a doubly important version milestone to cross. Not only is it much faster than 8.2, once your data is in 8.3, you can perform in-place upgrades from there.

Going from an earlier version to PostgreSQL 8.3 or later can be a difficult change. Some older applications rely on non-character data types being transparently cast to the type, a behavior removed from 8.3 for a variety of reasons. For details, see http://www.postgresql.org/docs/8.3/static/release-8-3.html.

While there's always a chance that upgrading your database ...