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Don Burleson Blog 







Oracle9i Upgrade and Migration Support

Migration to Oracle9i is tricky.  One of the most common performance problems after migrating to Oracle9i is poor performance precipitated by changes to the Oracle SQL optimizer.  The Oracle9i optimizer can switch to CPU-based costing (from I/O costing in Oracle8i) when you gather CBO statistics with dbms_stats.

We also have the Oracle9i bug 2820066 where CPU cost is computed whenever optimizer_index_cost_adj is set to a non-default value.  Unless you have applied the server patch set, your Oracle9i database may be generating CPU statistics, regardless of your CBO stats collection method.

After an Oracle9i migration you can turn-off CPU costing (and re-set costing to the Oracleu8i default with this hidden parm:  _optimizer_cost_model=io;

Need Oracle9i Migration Support?

B.C. provides Oracle9i Migration upgrades and Oracle9i upgrade support for all Oracle shops.  We have Oracle9i migration tools, Oracle9i upgrade training and Oracle9i support consulting.

Call Now for Oracle9i migration support!

Click here for a list of Oracle Consulting Services

BC provides world-class Oracle9i migration support and Oracle9i training and migration assistance.



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Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

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