Re: Improving count(*)
От | Zeugswetter Andreas DCP SD |
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Тема | Re: Improving count(*) |
Дата | |
Msg-id | E1539E0ED7043848906A8FF995BDA5799A53CF@m0143.s-mxs.net обсуждение исходный текст |
Ответ на | Improving count(*) (Simon Riggs <simon@2ndquadrant.com>) |
Ответы |
Re: Improving count(*)
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Список | pgsql-hackers |
> > Since that costs, I guess I would make it optional and combine it with > > materialized views that are automatically used at runtime, and can at > > the same time answer other aggregates or aggregates for groups. > > create materialized view xx_agg enable query rewrite as select > > count(*), sum (col1) from xx [group by col2]; > > > > I wonder how many times you really need a count(*) w/o where clause. > If I understand you correctly you are trying to optimize just this one case? I guess you have not read to the end. A materialized view with a group by as indicated in the example is able to answer all sorts of queries with or without where clauses ( e.g. ... where col2 = 'x'). Andreas
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