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 EnterpriseDB http://www.enterprisedb.com + If your life is a hard drive, Christ can be your backup. + ---------------------------(end of broadcast)--------------------------- 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
