From bed81bcbeca7fe983036165546efd7e5330fe9b0 Mon Sep 17 00:00:00 2001
From: Bruce Momjian
3.9) What are the pg_sorttempNNN.NN
files in my database directory?
+ 3.10) Why do I need to do a dump and restore
+ to upgrade PostgreSQL?
Operational Questions
@@ -776,6 +778,26 @@
not if a backend crashes during a sort. If you have no backends
running at the time, it is safe to delete the pg_tempNNN.NN
files.
The PostgreSQL team tries very heard to maintain compatability across + minor releases. So upgrading from 7.2 to 7.2.1 does not require a dump a + restore. However, new features are continuously being adding and + sometimes this requires new fields to be added to system tables. + +
These changes may be across many tables and so maintaining backward + compatability would be quite difficult. Thus, restoring from a dump is + required to make everything work. + +
Note that the actual on-disk file format does not change very often, + a feature the pg_upgrade script uses quite successfully. There the dump + is used create the necessary information in the system tables. The data + files are then just copied across. This method is not as guarenteed as + the dump/restore method but when it works it can make upgrades very + efficient. +