Re: postgres_fdw : altering foreign table not invalidating prepare statement execution plan.

On 2016/04/05 14:24, Amit Langote wrote:
> On 2016/04/05 0:23, Tom Lane wrote:
>> Amit Langote <amitlangote09@gmail.com> writes:
>>> Hm, some kind of PlanInvalItem-based solution could work maybe?
>>
>> Hm, so we'd expect that whenever an FDW consulted the options while
>> making a plan, it'd have to record a plan dependency on them?  That
>> would be a clean fix maybe, but I'm worried that third-party FDWs
>> would fail to get the word about needing to do this.
> 
> I would imagine that that level of granularity may be a little too much; I
> mean tracking dependencies at the level of individual FDW/foreign
> table/foreign server options.  I think it should really be possible to do
> the entire thing in core instead of requiring this to be made a concern of
> FDW authors.  How about the attached that teaches
> extract_query_dependencies() to add a foreign table and associated foreign
> data wrapper and foreign server to invalItems.  Also, it adds plan cache
> callbacks for respective caches.
> 
> One thing that I observed that may not be all that surprising is that we
> may need a similar mechanism for postgres_fdw's connection cache, which
> doesn't drop connections using older server connection info after I alter
> them.  I was trying to test my patch by altering dbaname option of a
> foreign server but that was silly, ;).  Although, I did confirm that the
> patch works by altering use_remote_estimates server option. I could not
> really test for FDW options though.
> 
> Thoughts?

I added this to next CF, just in case:
https://commitfest.postgresql.org/10/609/

Thanks,
Amit