[postgis-devel] Strange result about spatial indexes?

[Paul Ramsey]

gist_consistent is called a great deal, and for each call it gets
handed a pointer to a geometry. the consistency check is just whether
the bounding box of the key overlaps the bounding box of the geometry.
 rather than detoast the whole geometry we detoast the front slice
that contains the box, and then run the test.

Now, here's where some expert advice would be useful: what is the
gist_consistent test for?  we end up doing the bounding-boxes-overlap
check, but perhaps we could just return true all the time and
magic-would-occur. What's the purpose of the call?

P

On Fri, Aug 14, 2009 at 8:16 PM, Tom Lane<tgl at sss.pgh.pa.us> wrote:
> Paul Ramsey <pramsey at opengeo.org> writes:
>> Incidentally, I don't think switching our storage type is the
>> solution, it is treating the symptom (time spent in gist consistent)
>> rather than the disease (so very many calls into gist consistent).
>
> As far as I can tell from the profile, the time is being spent in
> accessing index entries.  How is heap_tuple_untoast_attr_slice involved
> at all?
>
>                        regards, tom lane
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