Re: Tips for upgrading from 7.4

Rick Schumeyer wrote:
> Tom Lane wrote:
>> Rick Schumeyer <rschumeyer@ieee.org> writes:
>>
>>> I'm working with someone who is about to upgrade from (I believe) pg
>>> 7.4 to pg 8.1.
>>>
>>
>>
>>> What would be the best resource to read to look for "gotchas"?
>>> Release notes?  At the moment, we don't care about performance
>>> problems, only things that might break.
>>>
>>
>> Reading the release notes is good, but you really really should test the
>> application(s) against a test 8.1 installation before you go live ...
>>
>>             regards, tom lane
>>
> We plan on testing.  I'm asking if there is anything that "everyone
> knows" will break that we might as well fix before testing.
Only to the extent that "everyone knows" the details of your PG
configuration and all connecting applications. Print the release-notes
chain and start reading/scribbling on it. Then expect to discover that
you don't know your apps as well as you thought.

We have encountered relatively few difficulties - most of ours revolved
around subtle changes to both automatic and explicit casting.

For example given and input of '<space>0<space>' you might see a change
from:

select ' 0 '::int;
ERROR:  invalid input syntax for integer: " 0 "

to this:

select ' 0 '::int;
 int4
------
    0

If you are already scrupulous about formatting and casting, you are
probably OK. If you relied on "getting away with" certain loose
behavior, you might find bugs.

BTW, why not upgrade to the latest version?

Cheers,
Steve