Tom Lane wrote:
> Heikki Linnakangas <[EMAIL PROTECTED]> writes:
> > Alvaro Herrera wrote:
> >> At this
> >> point I feel like the patch still needs some work and reshuffling before
> >> it is in an acceptable state. The fact that there are some API changes
> >> for which the patch needs to be adjusted makes me feel like we should
> >> put this patch on hold for 8.4. So we would first get the API changes
> >> discussed and done and then adapt this patch to them.
> > I hate to say it but I agree.
> I concur with putting this whole area off till 8.4. We do not have any
> consensus on what the API should be, which is exactly why the patch was
> never finished. All the proposals are pretty ugly.
> Another problem: frankly I'm pretty dissatisfied with the entire concept
> of not storing all the index keys, especially in the proposed way which
> would eliminate any outside control over whether keys are dropped or
> not. Two problems I can see with it are:
> 1. The performance hit for functional indexes could be really steep,
> since you'd need to recompute a potentially expensive function to
> recheck matches.
> 2. This would forever cut off any development of indexscans that make
> use of index key data beyond what btree itself knows how to do. An
> example of the sort of thing I'm thinking about is applying a LIKE or
> regex pattern match operator against the index key before visiting the
> heap --- not just a derived >= or <= condition, but the actual pattern
> match. We've discussed adding an index AM call that returns the key
> values, which'd allow the executor to apply non-btree operators to them
> before visiting the heap. But that idea is DOA if the planner can't
> tell in advance whether the entries will be available.
> So instead of pressing to try to get something into 8.3, I would rather
> we stand back and think about it some more.
I understand why you are saying hold for 8.4, but this issue came up in
the middle of the 8.3 development cycle and didn't get much attention.
I would like to know why it will get any more attention during 8.4.
Bruce Momjian <[EMAIL PROTECTED]> http://momjian.us
+ If your life is a hard drive, Christ can be your backup. +
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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