Db Query Tuning
- From: Sanjay Mishra <smishra_97@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 19 Feb 2007 08:52:30 -0800 (PST)
Hi
I had faced an interesting scenario yesterday when I moved some code from Dev
to QA and tried to execute the queries, they behaved very differently. QA was
newly refreshed with the data using Export/Import. I had clalcuated the Stat
using 9i DBMS_STATS and auto sample size. I had even copied the Stats from dev
to QA to make sure that stats are same but it still failed. The only difference
between Dev and QA is that QA might have few more record than Dev as Dev was
refreshed from Prod one week BAck. Anyway Data will continue to change in
Production and so I don't think that one week Data change shoudl be an issue.
There is no Hints been used and all init.ora setting including sga size are
same.
I had a script of around 15-20 query and each query is very big about 5-20
pages. Half of them are working fine while others are hanging. Trace will also
show that it is running but I appreciate if you can provide any insight as
what else can be done, Explain Plan is more or less the same except that their
sequence are different and I don't understand as why it happen when even Stats
are new or even copied using dbms_stats.export.. procedure.
TIA
Sanjay
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