RE: RE: query slow in 9i, but not slow in 8i

  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Wed, 3 Mar 2004 10:50:57 -0800

and Millsap with two Ls, not one.

> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx
> [mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Bobak, Mark
> Sent: mercredi, 3. mars 2004 10:21
> To: oracle-l@xxxxxxxxxxxxx
> Subject: RE: RE: query slow in 9i, but not slow in 8i
> 
> 
> Looks like you got a reply too.  By the way, his name is 
> Cary, not Carrie. ;-)
> 
> -----Original Message-----
> From: ryan.gaffuri@xxxxxxx [mailto:ryan.gaffuri@xxxxxxx]
> Sent: Wednesday, March 03, 2004 11:47 AM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: RE: RE: query slow in 9i, but not slow in 8i
> 
> 
> i put this on asktom and did a name drop to ensure a 
> response(hope that was ok). 
> 
> http://asktom.oracle.com/pls/ask/f?p=4950:8:469012999885085128
> 6::NO::F4950_P8_DISPLAYID,F4950_P8_CRITERIA:707586567563,
> 
> my post is at the bottom of the thread. 
> > 
> > From: "Cary Millsap" <cary.millsap@xxxxxxxxxx>
> > Date: 2004/03/03 Wed AM 10:50:30 EST
> > To: <oracle-l@xxxxxxxxxxxxx>
> > Subject: RE: RE: query slow in 9i, but not slow in 8i
> > 
> > Not a big query at all. If I recall correctly, the query 
> ran in about a
> > minute and a quarter--something like 1:15.0, with 1:14.5 
> consumed in the
> > parse. It was some kind of a bug, but I can't remember 
> which. Now that I
> > think about it, I'm not even sure whether it was histograms or
> > partitions that was causing the problem. Not a lot of 
> value, this foggy
> > anecdote of mine :).
> > 
> > 
> > Cary Millsap
> > Hotsos Enterprises, Ltd.
> > http://www.hotsos.com
> > * Nullius in verba *
> > 
> > Upcoming events:
> > - Performance Diagnosis 101: 3/23 Park City, 4/6 Seattle
> > - Hotsos Symposium 2004: March 7-10 Dallas
> > - Visit www.hotsos.com for schedule details...
> > 
> > 
> > -----Original Message-----
> > From: oracle-l-bounce@xxxxxxxxxxxxx
> > [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Mladen Gogala
> > Sent: Wednesday, March 03, 2004 8:23 AM
> > To: oracle-l@xxxxxxxxxxxxx
> > Subject: Re: RE: query slow in 9i, but not slow in 8i
> > 
> > Parse time over a minute? Was it a huge query or not? I 
> find it hard to
> > believe.
> > 
> > 
> > On 03/02/2004 09:36:10 PM, Cary Millsap wrote:
> > > I don't have access to the data to back this up, but I 
> have seen PARSE
> > > call response time move from over a minute to less than a 
> second by
> > > eliminating histograms from the equation. I think when I last saw
> > this,
> > > it was an Oracle8 system.
> > > 
> > > 
> > > Cary Millsap
> > > Hotsos Enterprises, Ltd.
> > > http://www.hotsos.com
> > > * Nullius in verba *
> > > 
> > > Upcoming events:
> > > - Performance Diagnosis 101: 3/23 Park City, 4/6 Seattle
> > > - Hotsos Symposium 2004: March 7-10 Dallas
> > > - Visit www.hotsos.com for schedule details...
> > > 
> > > 
> > > -----Original Message-----
> > > From: oracle-l-bounce@xxxxxxxxxxxxx
> > > [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of 
> Wolfgang Breitling
> > > Sent: Monday, March 01, 2004 10:30 PM
> > > To: oracle-l@xxxxxxxxxxxxx
> > > Subject: Re: RE: query slow in 9i, but not slow in 8i
> > > 
> > > There surely is some "cost" involved in evaluating a 
> histogram during
> > > the 
> > > parse phase, but I doubt that it will be significant enough to be 
> > > measurable. But histograms change the estimates of the 
> CBO and it is
> > > quite 
> > > possible that the presence of a histogram on a column where the
> > content
> > > is 
> > > not skewed enough to really warrant a histogram can change the
> > estimates
> > > 
> > > enough to cause the optimizer to use a different, slower 
> access path
> > > than 
> > > without the histogram.
> > > 
> > > At 09:14 PM 3/1/2004, you wrote:
> > > 
> > > >I am unfortunately speaking from heresay, however I 
> heard once that
> > > having
> > > >histograms all over the place can slow down parsing as 
> they have to
> > be
> > > >inspected.  I was left with the impression that unless 
> the data is
> > > skewed
> > > >enough to warrant a histogram then there actually is a 
> negative cost
> > > >associated with having too many histograms.
> > > >
> > > >Surely someone on this list can either support me or 
> shoot me down on
> > > this
> > > >one?
> > > 
> > > Wolfgang Breitling
> > > Oracle7, 8, 8i, 9i OCP DBA
> > > Centrex Consulting Corporation
> > > http://www.centrexcc.com 
> > > 
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