Re: Exposing PG_VERSION_NUM in pg_config

On 3/25/15 2:00 PM, Andres Freund wrote:
> On 2015-03-25 14:50:44 -0400, Tom Lane wrote:
>> >Jim Nasby<Jim.Nasby@BlueTreble.com>  writes:
>>> > >On 3/24/15 6:26 PM, Tom Lane wrote:
>>>> > >>Hm.  We're all agreed that there's a use case for exposing PG_VERSION_NUM
>>>> > >>to the makefiles, but I did not hear one for adding it to pg_config; and
>>>> > >>doing the former takes about two lines whereas adding a pg_config option
>>>> > >>entails quite a lot of overhead (documentation, translatable help text,
>>>> > >>yadda yadda).  So I'm not in favor of doing the latter without a much
>>>> > >>more solid case than has been made.
>> >
>>> > >Why else would you want the version number other than to do some kind of
>>> > >comparison?
>> >
>> >The question is why, if we supply the version number in a make variable,
>> >you would not just use that variable instead of having to do
>> >"$(shell $(PG_CONFIG) --something)".  The shell version adds new failure
>> >modes, removes none, and has no redeeming social value that I can see.
> I think using the makefile is preferrable if you have the version
> dependency in the makefile. But if you don't actually use make
> (e.g. stuff not written in C) or you need the detection in configure or
> something, it's different.

Exactly; not every problem can be solved by make. I know I've had to 
futz with the output of "SELECT version()" in the past, and I think I've 
had to do the same with pg_config --version.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com