Re: Removing INNER JOINs

On Wed, Dec 03, 2014 at 02:08:27PM -0500, Tom Lane wrote:
> Heikki Linnakangas <hlinnakangas@vmware.com> writes:
> > Do you need to plan for every combination, where some joins are removed 
> > and some are not?
> 
> I would vote for just having two plans and one switch node.  To exploit
> any finer grain, we'd have to have infrastructure that would let us figure
> out *which* constraints pending triggers might indicate transient
> invalidity of, and that doesn't seem likely to be worth the trouble.
> 
> > I hope the same mechanism could be used to prepare a plan for a query 
> > with parameters, where the parameters might or might not allow a partial 
> > index to be used. We have some smarts nowadays to use custom plans, but 
> > this could be better.
> 
> Interesting thought, but that would be a totally different switch
> condition ...
> 
>             regards, tom lane
> 

Or between a node with a low rows count and a high rows count for those
pesky mis-estimation queries.

Regards,
Ken