Re: Scary 10gR2 query problem

  • From: fairlie rego <fairlie_r@xxxxxxxxx>
  • To: Ian.Cary@xxxxxxxxxxxxxxxxxxxx, stellr@xxxxxxxxxx, oracle-l <oracle-l@xxxxxxxxxxxxx>
  • Date: Wed, 24 May 2006 06:28:34 -0700 (PDT)

Hi Ian,
  Assuming the problem is with the optimizer do you get correct results if you 
  set optimizer_features_enable to 10.1.0 at the session level?
"Ian Cary (C)" <Ian.Cary@xxxxxxxxxxxxxxxxxxxx> wrote:
As there seem to a few people using 10.2 ( on Solaris 9 in my
case) I thought I'd share a scary issue with you all.

Odd in the example below is a reasonably complex view that has been
working fine in 10.1 for quite a while.

MP409SH2> select count(*) from odd;


Elapsed: 00:01:15.56
MP409SH2> create table very_odd as select * from odd;

Table created.

Elapsed: 00:07:34.00
MP409SH2> select count(*) from very_odd;


Elapsed: 00:00:01.84

This is a 100% genuine case where the select statement returns the wrong
(substantially) number of rows. In 10.1 the view returns the correct
67311 rows.
There doesn't seem to be any pattern or reason for the error and I only
noticed it because I had the 10.1 results to hand. 
I'll be raising a tar as soon as Metalink sorts itself out but I thought
I'd share this as I'm not sure I can 100% trust the results of any
select statement on 10.2



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          Fairlie Rego
Senior Oracle Consultant
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