Re: hstore equality-index performance question
От | Stefan Keller |
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Тема | Re: hstore equality-index performance question |
Дата | |
Msg-id | 25bc040b1003300827r436c2534je3cad9a1f8571559@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: hstore equality-index performance question (Sergey Konoplev <gray.ru@gmail.com>) |
Ответы |
Re: hstore equality-index performance question
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Список | pgsql-general |
You are right, my negligence. I'm trying to optimize the latter query: # SELECT id, (kvp->'a') FROM mytable WHERE kvp ? 'a'; ...or something like this (which also involves the '->' operator) # SELECT id FROM mytable WHERE (kvp->'a') = 'x'; -S. 2010/3/29 Sergey Konoplev <gray.ru@gmail.com>: >> My question is, if one can get also index support for the '->' operator? > > I am not sure what do you mean. > >>>> SELECT id, (kvp->'a') FROM mytable; >>>> >>>> ... can be accelerated nevertheless by adding following where clause: >>>> >>>> SELECT id, (kvp->'a') FROM mytable WHERE kvp ? 'a'; >>>> >>>> => Is this correct? > > These queries could return completely different result sets. First > query returns all the records with the value of kvp->'a' if kvp has > 'a' key and NULL otherwise. Second one returns only those records > where kvp has 'a' key. > > -- > Sergey Konoplev > > Blog: http://gray-hemp.blogspot.com / > Linkedin: http://ru.linkedin.com/in/grayhemp / > JID/GTalk: gray.ru@gmail.com / Skype: gray-hemp / ICQ: 29353802 >
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