On Mon, Oct 31, 2005 at 03:27:31PM -0500, Merlin Moncure wrote: > > On Mon, Oct 31, 2005 at 12:32:03PM -0500, Merlin Moncure wrote: > > > if that index is causing the problem, you may want to consider setting > > > up partial index to exclude null values. > > Hey all. > > Pardon my ignorance. :-) > > I've been trying to figure out whether null values are indexed or not from > > the documentation. I was under the impression, that null values are not > > stored in the index. Occassionally, though, I then see a suggestion such > > as the above, that seems to indicate to me that null values *are* stored > > in the index, allowing for the 'exclude null values' to have effect? > > Which is it? :-) > I think I'm the ignorant one...do explain on any lookup on an indexed > field where the field value is null and you get a seqscan.
Nahhh... I think the documentation could use more explicit or obvious explanation. Or, I could have checked the source code to see. In any case, I expect we aren't the only ones that lacked confidence. Tom was kind enough to point out that null values are stored. I expect that the seqscan is used if the null values are not selective enough, the same as any other value that isn't selective enough. Now we can both have a little more confidence! :-) Cheers, mark -- [EMAIL PROTECTED] / [EMAIL PROTECTED] / [EMAIL PROTECTED] __________________________ . . _ ._ . . .__ . . ._. .__ . . . .__ | Neighbourhood Coder |\/| |_| |_| |/ |_ |\/| | |_ | |/ |_ | | | | | | \ | \ |__ . | | .|. |__ |__ | \ |__ | Ottawa, Ontario, Canada One ring to rule them all, one ring to find them, one ring to bring them all and in the darkness bind them... http://mark.mielke.cc/ ---------------------------(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