On 10/09/2014 10:25 PM, Peter Geoghegan wrote:
> On Thu, Oct 9, 2014 at 12:14 PM, Heikki Linnakangas
> <hlinnakangas@vmware.com> wrote:
>> B-tree index build uses tuplesort.c. What's missing?
>
> I don't think that all that much is missing. Tuplesort expects to work
> with an index scankey when sorting B-Tree tuples. There needs to be
> something like a reverse lookup of the sortsupport function. It looks
> like a historical oversight, that would take time to fix, but wouldn't
> be particularly challenging. You'd need to pick out the operators from
> the scankey, so you'd have something like what tuplesort_begin_heap()
> starts off with with tuplesort_begin_index_btree().
Oh, I didn't realize we don't do that already! I'm surprised, I would've
expected index build to have been the first thing we'd use the
SortSupport stuff in.
Yeah, that seems worth doing, independently of the this patch. Can you
write a separate patch to use SortSupport for B-tree index builds,
please? Eliminating the FunctionCallInfoData overhead should shave off
some some cycles from every index build.
- Heikki
