Re: Further thoughts about warning for costly FK checks

Fabien COELHO wrote:
> 
> > > Or maybe some new "ADVICE" or "ODDITY" level next to "DEBUG NOTICE
> > > WARNING ERROR PANIC...", that would be hidden by default and triggered
> > > by an option?
> >
> > But that doesn't really solve the problem, which is that there are
> > conditions that it's difficult to test for on-the-fly while a schema is
> > being constructed.
> 
> Ok, I was off my shoes again, sorry.
> 
> > A pg_advisor tool would look at the completed schema and would not have
> > that problem.
> 
> Ok.
> 
> As a more interesting contribution to the issue, I would suggest that such
> checks could be triggered by "ANALYSE".
> 
> 1/ it is the first thing to be done on performance problems.
> 
> 2/ it is not done too often.
> 
> 3/ checking this stuff seems to belong to the analyse phase.
>    warnings about costly foreign key checks could also be repeated
>    on these occasions.
> 
> Also, because of the opposition by some DBA, these checks could be disable
> by some options, but I would suggest the option to be on by default.

I was thinking of a GUC variable called PERFORMANCE_HINTS, which would
throw a message if a lookup from the primary to the foreign key didn't
have an index.

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