Re: [HACKERS] 6.5 beta and ORDER BY patch

Hannu Krosing wrote:
>
> Jan Wieck wrote:
> > >
> > > Is the patch by Jan that eliminated the duplicate sort node in case it
> > > was redundant included in 6.5 ?
> >
> > Sorry,
> >
> > I missed to put it into after v6.4 release. And since it
> > wasn't there during v6.5 development, I would not put it in

...

> But if it is not relesed it will _never_ be tested enough ...
>
> As we are just going into beta, not relese, I would suggest to put
> it in now, and back out if it relly breaks anything.

I will download the latest snapshot tonight and test the patch there.

Does anyone know if something introduced in 6.5 can break by omitting
the top sort node ?

Perhaps any of the following:

* MVCC

* temp tables

* Some exotic use of rules

* SELECT FOR UPDATE

I myself can't see how it could break, as the only thing the patch does
is omitting a top sort node if the query is already in the right
order. So it should be equivalent of just not including the ORDER BY
in the SELECT in the first place.

Jan - I often feel the same about some of my code that are part of some
larger complex project (ie. if it aint broke, don't fix it), but this
time
I think the patch is quite safe, and very very useful for at least two
occasions: getting the start of some table out to users web and for
processing
huge tables in predictable/repeatable order.

I somewhat understand your hesitation, because I can't either think of
any test
in regression that could be broken by the patch, but instead of making
me
uneasy it makes me happy ;)

-----------------
Hannu