Re: report generation from table.
От | A. Kretschmer |
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Тема | Re: report generation from table. |
Дата | |
Msg-id | 20091021121607.GA1086@a-kretschmer.de обсуждение исходный текст |
Ответ на | report generation from table. (sathiya psql <sathiya.psql@gmail.com>) |
Ответы |
Re: report generation from table.
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Список | pgsql-sql |
In response to sathiya psql : > Hi All, > > I have been searching for, Preparing report from a huge table. > > Queries am executing now are, > SELECT count(*) from HUGE_TBL where cond1, cond2; > SELECT count(*) from HUGE_TBL where cond1, cond3; > --- like this i have different conditions(10-15 different things ) and > different amount of conditions ( 2 - 5 condition ). > > As that is a very huge table, it took time to execute each query ( 2 min ). And > finally it takes 15 times that ( 30 min ). Is there anyway to do the above > report efficiently ? > > Such executing the query only once, and getting all different outputs required > ? or fetching result from some cache ? select sum(case when <cond1> and <cond2> then 1 else 0 end) as query1, sum(case when <cond1> and <cond3> then 1 else 0 end) as query2, ... from table; It forces a whole seq. scan, but only once. Regards, Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
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