Re: Win2K Questions
От | Jean-Luc Lachance |
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Тема | Re: Win2K Questions |
Дата | |
Msg-id | 3DCFDA27.5AF840D3@nsd.ca обсуждение исходный текст |
Ответ на | Re: Win2K Questions ("scott.marlowe" <scott.marlowe@ihs.com>) |
Ответы |
Re: Win2K Questions
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Список | pgsql-general |
This explains it all. What would be involved in adding version and visibility to the index? It would allow for scanning the index instead of the whole table for many of the count() request. JLL Neil Conway wrote: > > Jean-Luc Lachance <jllachan@nsd.ca> writes: > > unless id is indexed there is nothing that can be done with > > select count(*) from table where id >10000; > > Otherwise, the index should be scanned, not the table. > > Indexes don't store heap tuple visibility information; you'd need to > scan the heap as well in order to determine which tuples your > transaction can see. > > Cheers, > > Neil > > -- > Neil Conway <neilc@samurai.com> || PGP Key ID: DB3C29FC
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