Re: index-only scans

On Sat, Oct 15, 2011 at 2:16 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> On Fri, Oct 7, 2011 at 11:40 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>>> Please find attached a patch implementing a basic version of
>>> index-only scans.
>>
>> I'm making some progress with this, but I notice what seems like a
>> missing feature: there needs to be a way to turn it off.  Otherwise
>> performance comparisons will be difficult to impossible.
>>
>> The most obvious solution is a planner control GUC, perhaps
>> "enable_indexonlyscan".  Anyone object, or want to bikeshed the name?
>>
>
> Currently I can't force an indexonlyscan over an indexscan, because of
> the way the enable_* variables work.

OK, scratch that. I must have been using the wrong query (for
which the index was not covering), as I can't reproduce the
behavior nor looking at the code can I see how it could have
occurred in the first place.

Cheers,

Jeff