Hi All,

I currently have an open Issue with Ingres Corp. where the performance
of several queries has degraded significantly since upgrading to 9.2 +
Patch 13556.

The culprit is the fix for bug 122556 which has solved someone else’s
performance but has degraded mine!

The work-around is to use SET NOFLATTEN before executing a ‘bad’
query, until Ingres Corp. produce a fix that generates a good
flattened plan.

Whilst waiting for Ingres to fix the Issue, I remembered a
conversation I had with an Ingres engineer at, IIRC the UKIUA at
Blackpoll.

His idea was that in extreme conditions where Ingres can’t help but
produce a ‘bad’ plan, a method could be employed to make Ingres
evaluate the best flattened plan AND the best un-flattened plan and
choose the best overall plan i.e. compile two plans and pick the best
one.

I have raised an Enhancement Request (142141) to see if this idea can
be added to Ingres.

If you think that this idea has merit, can you please contact Ingres
Tech. Support and/or your Ingres A/C Mgr. and add weight in support to
this enhancement?

TIA

On Jan 15, 2010, at 8:06 AM, rthdavid wrote:

That might have been me ... I suggested something like this
to Doug back in the early 90's. It's not as easy as it
sounds; you'd have to make a duplicate copy of the entire
parser output first, because OPF likes to muck with the
parse tree as it operates. You're also relying on good
optimizer estimates, so it probably shouldn't even try
the two-plan trick unless good stats are available.
It's probably doable, if not easy.

Karl

On 15 Jan, 13:43, Karl Schendel <schen... (AT) kbcomputer (DOT) com> wrote:
Yes. It was you. :-)

The Blackpool UKIUA was one of the best jolly's ever.

Only CA World 1999 beats it...

rthdavid wrote:

I can only assume you weren't at CA Worlds 1995/6/7 then... (But I think
you *were* at one of those, weren't you?) Then there was the
Engineering Summit in 2008, which set a new highwater mark IMO.

Sadly I missed Blackpool, but if anyone (such as yourself) would like to
help make IUA 2010 (vide infra) the "best jolly ever" feel free to get
in touch with me.

--
Roy

UK Ingres User Association Conference 2010 will be on Tuesday June 8 2010
Go to http://www.iua.org.uk/join to get on the mailing list.