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Re: Strange limit and offset behaviour....

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On Sat, 7 Feb 2009 15:49:49 -0600
"Adam Rich" <adam.r@xxxxxxxxxxxxx> wrote:

> > 
> > I have the following sql:
> > 
> > SELECT * from table order by dato asc limit 20 offset 0
> > 
> > 
> > This gives me different rows than the 20 first rows when running the
> > following sql:
> > 
> > SELECT * from table order by dato asc
> > 
> > 
> > Shouldn't the 20 first rows in the second sql statment be the same 20
> > rows that is returned in the first statement
> > or am I missing something?
> > 
> 
> Not necessarily.  In your example query, if "dato" was not a unique
> column, and there were some duplicates, the "top 20" values is not
> a defined set.  Adding the offset clause might cause a different
> query plan, resulting in a different ordering of the duplicate values.
> 
> 
I found out that if I created an index on the dato field, then I got the same 20 rows... Does that make sense or is
it just a coincedense?

BTJ

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