Re: So, is COUNT(*) fast now?

On Fri, Oct 21, 2011 at 3:07 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> [ oprofile results ]

*grovels through the line-by-line results*

Hmm, I guess there is a bit of a hotspot in StoreIndexTuple, which is
probably being folded into IndexOnlyNext in the per-function timings:

ExecClearTuple(slot);
for (i = 0; i < nindexatts; i++)
values[i] = index_getattr(itup, i + 1, itupdesc, &isnull[i]);
ExecStoreVirtualTuple(slot);

If I'm reading these results right, that section is about 3% of the
total number of samples.

Also, this line is kind of expensive:

if (!visibilitymap_test(scandesc->heapRelation,
ItemPointerGetBlockNumber(tid),
&node->ioss_VMBuffer))

Around 2%. But I don't see any way to avoid that, or even make it cheaper.

--
Robert Haas
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