Re: Optimizer & boolean syntax
От | Christopher Kings-Lynne |
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Тема | Re: Optimizer & boolean syntax |
Дата | |
Msg-id | 003101c291a9$525b4950$6600a8c0@internal обсуждение исходный текст |
Ответ на | Re: Optimizer & boolean syntax (Stephan Szabo <sszabo@megazone23.bigpanda.com>) |
Ответы |
Re: Optimizer & boolean syntax
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Список | pgsql-hackers |
> > Are those two syntaxes eqivalent ? > > > > select * from users where monitored; > > select * from users where monitored=true; > > > > If the answer is yes, the optimimer probably doesn't agree with you :) > > That depends on the definition of equivalent. They presumably give the > same answer (I'm assuming monitored is a boolean), but the latter has > something that's considered an indexable condition and I believe the > former does not (even with enable_seqscan=off the former syntax > appears to give a sequence scan, usually a good sign it's not considered > indexable). I think his point is that they _should_ be equivalent. Surely there's something in the optimiser that discards '=true' stuff, like 'a=a' should be discarded? Chris
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