Thread: Negative offsets

Negative offsets

From
CSN
Date:
I was playing around with negative offsets:

select * from table1 order by col1 offset -5 limit 25;
select * from table1 order by col1 offset -25 limit
25;
select * from table1 order by col1 offset -250 limit
25;

They all return the same resultset (offset 0). Is
there even any point in allowing negative offsets -
such as maybe someday they'll offset backwards?

thanks
csn

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Re: Negative offsets

From
Bruce Momjian
Date:
CSN wrote:
> I was playing around with negative offsets:
>
> select * from table1 order by col1 offset -5 limit 25;
> select * from table1 order by col1 offset -25 limit
> 25;
> select * from table1 order by col1 offset -250 limit
> 25;
>
> They all return the same resultset (offset 0). Is
> there even any point in allowing negative offsets -
> such as maybe someday they'll offset backwards?

Actually we allow negative offsets and limits.  Seems we should disallow
them.  Yes, it would be interesting if they did offsets relative to the
end of the result set.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
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Re: Negative offsets

From
"Jim C. Nasby"
Date:
On Fri, Dec 16, 2005 at 07:14:42PM -0500, Bruce Momjian wrote:
> Actually we allow negative offsets and limits.  Seems we should disallow
> them.  Yes, it would be interesting if they did offsets relative to the
> end of the result set.

Either interesting or a great way to introduce bugs... AFAIK you can
always get the same behavior just by reversing the sort order, so I'd
lean towards not allowing negative offsets.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

Re: Negative offsets

From
Bruce Momjian
Date:
Bruce Momjian wrote:
> CSN wrote:
> > I was playing around with negative offsets:
> >
> > select * from table1 order by col1 offset -5 limit 25;
> > select * from table1 order by col1 offset -25 limit
> > 25;
> > select * from table1 order by col1 offset -250 limit
> > 25;
> >
> > They all return the same resultset (offset 0). Is
> > there even any point in allowing negative offsets -
> > such as maybe someday they'll offset backwards?
>
> Actually we allow negative offsets and limits.  Seems we should disallow
> them.  Yes, it would be interesting if they did offsets relative to the
> end of the result set.

Seems most people just want to leave our current behavior unchanged.

--
  Bruce Momjian   http://candle.pha.pa.us
  SRA OSS, Inc.   http://www.sraoss.com

  + If your life is a hard drive, Christ can be your backup. +