Tom Lane wrote:
> If I'm not mistaken, that's a DB2-ish locution
It could also be a part of the Oracle vernacular. I've seen queries like
that running against Oracle RDBMS, too.
> for a query with DISTINCT
> ON, ie, you're looking for the row with highest _revision_created for
> each value of id. It might perform well on DB2, but it's going to
> mostly suck on Postgres --- we don't optimize window-function queries
> very much at all at the moment.
Hmmm, what optimizations do you have in mind? I thought that window
functions are just clever tricks with memory? Anything that can be
expected for 9.0x?
> Try writing it with DISTINCT ON instead
> of a window function, like so:
>
Wouldn't "distinct" necessarily bring about the sort/merge?
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