Even Rouault wrote:
Martin,
I take the liberty to CC the list, as it is an interesting issue and it's better
to go public if we want to make progress on that.
In a few words, this is about how we could speed up GetFeature() on the layers
returned when issuing a SQL request on OGR drivers that rely on databases : PG
driver, MySQL driver, SQLite driver (... ?). For people wanting to take part,
you might be interested in the below email exchange first.
After examining Martin's patches and reading its explanations, I cann see 2
possibilities if we want to implement such optimization :
Even,
I haven't seen Martin's patches, but the normal way to provide indexed
access to resultsets is the OGRLayer::SetNextByIndex() method. You
pass the index into the current result set and then GetNextFeature()
should read the indicated feature.
Currently only very few providers implement this in a customized way,
but it seems it would be better to expand that rather than introduce
a new mechanism.
Does this make sense?
PS. there are reasonably good reasons why we want the FID to be the
primary key where practical. I would hate to break that.
Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, [email protected]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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