Bug 5047758 - RMAN Performance Degradation

Posted at Monday, June 18, 2007
Upon moving to 10g, you may experience poor performance when using RMAN with a 10g recovery catalog. Resync operations, in particular will run extremely slow, increasing the overall amount of time your backup jobs take to run to fruition.

This is Bug #5047758 as documented in Metalink note 247611.1.

To remedy this, issue the following command and/or include it in any stored scripts you might be using:

sql "alter session set optimizer_mode=RULE";

Or nest in your stored script or run block:

CREATE SCRIPT SAMPLE_SCRIPT {
sql "alter session set optimizer_mode=RULE";
}

Oracle also recommends that in response you gather the fixed objects' statistics via: exec dbms_stats.gather_fixed_objects_stats() on the recovery catalog database(s) in question.

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