Re: Index not used with IS NULL
От | Dima Tkach |
---|---|
Тема | Re: Index not used with IS NULL |
Дата | |
Msg-id | 3E50F4F6.5000704@openratings.com обсуждение исходный текст |
Ответ на | Re: Index not used with IS NULL (Stephan Szabo <sszabo@megazone23.bigpanda.com>) |
Список | pgsql-general |
> > >Yes, this solution does double index the NULLs, but if you have alot of >NULLs you probably should be doing a seqscan to find them anyway and don't >need the index. High update frequency costs you the NULL check, which is >a little annoying, and if you've got a small number of NULL rows or the >data is clustered in some fashion (so that the index is a win) that have >lots of updates this may become significant. > > Yeah... But imagine the real-life condition, when I have a *moderate* number of nulls (not enough to justify a seq.scan, but still a lot) in *several* different columns - so that, instead of creating a single multi-column index, I would have to create a whole bunch of them with different predcates - where this is null and that is not null, where this is null and tha is null etc, etc... That's what annoys me a lot here :-(
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