Re: Recursive Left Joins Causing Trouble in 8.2.3 RESOLVED (kind of)

On 2/21/07, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Ian Harding" <harding.ian@gmail.com> writes:
> > I had views that used syntax like
> > WHERE datecol < current_date and (otherdatecol is null or otherdatecol
> > > current_date)
> > Suddenly, this is ungodly inefficient in 8.2.3.  It worked just fine in 8.1.3.
>
> This complaint is pretty much content-free (especially with the oblique
> implication that it's got something to do with left joins).  Please
> provide a self-contained test case.
>
>                         regards, tom lane
>

True.  Yesterday was my last day at that employer, today is my first
at my new one.  I needed to get things going and was just happy to be
able to turn enable_nestloop back on and have things work.

I will see if I can get the problem recreated without too much
extraneous junk, it was buried pretty deep in views referencing views
referencing views which took what may be a minor change in query
timing and planning complexity and blowing it out.  The odd query
structure (I thought) was a series of self left-joins but that may
have been smoke.

I was just surprised that basically my entire system came to a halt
with a minor version upgrade, and that nobody else had seen anything
similar.  I know I write careless SQL from time to time, but again, I
didn't think I was THAT unique!

- Ian