Tom Lane <[EMAIL PROTECTED]> writes:

> Greg Stark <[EMAIL PROTECTED]> writes:
> > The thing is that these opclasses you're describing are closely related. It
> > ought to be possible to use a single index to produce results in any of the
> > four orders you describe.
> 
> Wrong --- only two of them.  You can't magically swap nulls from one end
> of the index to the other (and Hannu's flight of fantasy about double
> indexscans is just a flight of fantasy; it would be solving the problem
> at entirely the wrong place).

I think that was my flight of fantasy. I didn't say it was pretty but it would
solve the problem. Whereas having a separate opclass would mean someone would
need a second index to satisfy the ordering which seems silly.

-- 
greg


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TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not
       match

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