[postgis-devel] postgis proc upgrade

[strk at refractions.net]

I've added an initial procedures upgrade script
in the HEAD branch. 

When postgis_full_version() warns you that proc
upgrade is required you can try that script.

The script will only do something if the SCRIPTS
versions are compatible, which is they share the same
MAJOR and MINOR numbers.

When upgrading the lwpostgis.sql.in file we *MUST*
pay attention to what represent a compatible change
and what doesn't.

I think we should consider *COMPATIBLE* every change
that can be accessed to using the postgis_proc_upgrade
script.

(is it a snake byting its tail ?)

The script basically extracts all CREATE OR REPLACE FUNCTION
blocks, which is so far the only safe way to upgrade scripts
objects I found. This mean that currently a compatible
change is a function addition or function body modification.

Every other change is  *INCOMPATIBLE* at the current stage
so must trigger a MINOR or MAJOR version increment.

I suggest we take care of verifying every change in the
lwpostgis.sql.in so to either improve the
postgis_proc_upgrade script or find another way of
doing the changes in a backward compatibility manner
or finally just upgrade the MINOR-up numbers.

Comments welcome.

--strk;