Обсуждение: Scan Direction not part of ScanState?

Hi,

I notice that the IndexScan code looks up the scan direction each
invocation by looking up the direction of the plan. Does this mean the
direction can change in the middle of a scan? Is this how MOVE
FORWARD/BACKWARD works?

I've traced the code and it *appears* this is what's happening, but can
anyone clarify?

Thanks in advance,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.

Martijn van Oosterhout <kleptog@svana.org> writes:
> I notice that the IndexScan code looks up the scan direction each
> invocation by looking up the direction of the plan. Does this mean the
> direction can change in the middle of a scan? Is this how MOVE
> FORWARD/BACKWARD works?

Yes, yes.
        regards, tom lane