Re: [GENERAL] indexed regex select optimisation missing?
От | Peter Eisentraut |
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Тема | Re: [GENERAL] indexed regex select optimisation missing? |
Дата | |
Msg-id | Pine.GSO.4.02A.9911041037050.1524-100000@Hund.DoCS.UU.SE обсуждение исходный текст |
Ответ на | Re: [GENERAL] indexed regex select optimisation missing? (Stuart Woolford <stuartw@newmail.net>) |
Ответы |
Re: [GENERAL] indexed regex select optimisation missing?
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Список | pgsql-general |
On Thu, 4 Nov 1999, Stuart Woolford wrote: > unfortunately '^whatever.*' is what I'm trying to locate (ie: all words > starting with whatever, but with nay trailing text), the problem seems to be in > the termination of the index scan, not in the actual regex match (which actually > seems very good, speed wise..) otherwise I could just use ='whatever', which > runs very very fast. Isn't "all words that start with whatever but without trailing text" the same as = 'whatever'? From a regex point of view '^whatever' and '^whatever.*' are exactly equivalent, but I can see where one could fail to optimize properly. But that could even be a problem in the regex library, which is not any of the PostgreSQL developers' domain and which is used in other products as well. -Peter -- Peter Eisentraut Sernanders vaeg 10:115 peter_e@gmx.net 75262 Uppsala http://yi.org/peter-e/ Sweden
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