Re: [HACKERS] adate::Date is equiv. to adate if adate is type of Date ?
От | Oleg Bartunov |
---|---|
Тема | Re: [HACKERS] adate::Date is equiv. to adate if adate is type of Date ? |
Дата | |
Msg-id | Pine.GSO.3.96.SK.990504194233.16881B-100000@ra обсуждение исходный текст |
Ответ на | Re: [HACKERS] adate::Date is equiv. to adate if adate is type of Date ? (Thomas Lockhart <lockhart@alumni.caltech.edu>) |
Список | pgsql-hackers |
On Tue, 4 May 1999, Thomas Lockhart wrote: > Date: Tue, 04 May 1999 13:12:07 +0000 > From: Thomas Lockhart <lockhart@alumni.caltech.edu> > To: Oleg Bartunov <oleg@sai.msu.su> > Cc: Postgres Hackers List <hackers@postgreSQL.org> > Subject: Re: [HACKERS] adate::Date is equiv. to adate if adate is type of Date ? > > > > > btw, how I can find 'something' older than a month > > > select * from titles > > > where adate::date < 'today'::Date - '1 month'::timespan; > > this problem doesn't works: > > apod=> select * from titles > > apod-> where adate::date < 'today'::Date - '1 month'::timespan; > > ERROR: There is more than one possible operator '<' > > for types 'date' and 'datetime' > > but if I specify Datetime instead of Date it works, but still doesn't > > use index. > > apod=> explain select * from titles > > apod-> where adate::datetime < 'today'::Datetime > > apod-> - '1 month'::timespan; > > NOTICE: QUERY PLAN: > > Seq Scan on titles (cost=64.10 size=466 width=28) > > OK, try > > select * from titles > where adate < date('today'::Datetime - '1 month'::timespan); > > although there may (still) be problems with Postgres recognizing that > it could use an index when the "constant" is an expression. > > Let us know what you find out... No, it's doing Seq Scan. I checked with 6.4.2 and current 6.5 cvs Oleg > > - Tom > > -- > Thomas Lockhart lockhart@alumni.caltech.edu > South Pasadena, California > _____________________________________________________________ Oleg Bartunov, sci.researcher, hostmaster of AstroNet, Sternberg Astronomical Institute, Moscow University (Russia) Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/ phone: +007(095)939-16-83, +007(095)939-23-83
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