Hello
In 11g and 12c, I used to disable the parameter _optimizer_use_feedback
because the re-optimization was always producing a suboptimal execution
plan. But I kept this parameter enabled while upgrading to 19c. And, after
more than 10 19c upgrades I haven’t noticed any performance issue induced
by the cardinality feedback feature. Until today, where a bunch of queries
changed their execution plan (from 1 second on average to 300 seconds)
because of cardinality feedback usage
Are you still disabling this feature in 19c?
Thanks
Mohamed Houri
--
Houri Mohamed
Oracle DBA-Developer-Performance & Tuning
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