Re: Client application name

On Wed, Oct 21, 2009 at 12:45, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Wed, 2009-10-21 at 11:20 +0100, Dave Page wrote:
>> On Wed, Oct 21, 2009 at 11:06 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>>
>> > The SET seems sufficient for me. All interfaces currently support it.
>>
>> SET alone will not allow what I see as one of the most useful uses of
>> this - consider:
>>
>> PGAPPLICATIONNAME="Nightly backup" pg_dump mydb
>> PGAPPLICATIONNAME="Sensor data import" psql < data.log
>
> This highlights a different issue. If you wish to pass arbitrary SET
> parameter(s) to a client then it is difficult to do so. We would be
> better off solving that generic problem than solving your specific one.
>
> Consider
>
> PGDEADLOCKTIMEOUT=1 pg_dump mydb
> PGWORKMEM=32657 psql < data.log
>
> Same requirement as setting the appname. Specific code for each
> parameter is the wrong way to do that.

PGOPTIONS is the way to do that, no? It can be a bit tricky when you
have to deal with quoting, but it is there and it works...

>> Also, adding something to libpq means we have to alter all the clients
>> > and that means they become incompatible with earlier versions. What
>> > advantage comes from doing all of that work? Nothing even close to large
>> > enough to warrant the pain and delay, AFAICS.
>>
>> I must be missing something - why do we have to alter the clients? As
>> it stands, they can use SET with whatever libpq they currently have,
>> however if they wish to use the environment or connection string
>> they'll need to update to the new libpq version. Those apps that don't
>> care won't be affected because the libpq API hasn't changed in any way
>> that isn't fully backwards compatible.
>
> If they can use SET, why are we changing libpq? If we are changing
> libpq, why would we ignore those changes in the clients? (We don't need
> to change clients, but most clients expose some language specific
> feature to set things rather than just ignore them and let them be set
> via libpq).

The idea is to provide a better default than an empty string, I think.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/