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Oracle 9i Upgrade and Migration Support

Migration from Oracle 8i to Oracle 9i is tricky.  Foremost after migrating to Oracle 9i is poor performance from changes to the Oracle SQL optimizer.  The Oracle 9i CBO can switch to CPU-based costing (from I/O costing in Oracle 8i) when you gather statistics with dbms_stats.

Oracle 9i bug 2820066 is an Oracle9i migration issue because 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 Oracle 9i database may be generating CPU statistics, regardless of your CBO stats collection method.

After an Oracle 9i migration you can turn-off CPU costing (and re-set costing to the Oracleu8i default with this hidden parm:  _optimizer_cost_model=io;

Need Oracle 9i Migration Support?

B.C. provides Oracle 9i Migration upgrades and Oracle 9i upgrade support for all Oracle shops.  We have Oracle 9i migration tools, Oracle 9i upgrade training and Oracle 9i support consulting.

Call Now for Oracle 9i migration support!

Click here for a list of Oracle Consulting Services

BC provides world-class Oracle 9i migration support and Oracle 9i 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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Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

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