Re: [HACKERS] adate::Date is equiv. to adate if adate is type of Date ?

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