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Why does a hard parse for a complex sql query using some views take longer after upgrade to 12.1.0.2

edited Feb 6, 2015 10:09AM in SQL Performance (MOSC) 5 commentsAnswered

Hello,

we have an complex SQL query which uses a with block and some views. In Oracle 11.2.0.x it takes 8 seconds for parsing the statement for the first time. After upgrading to Oracle 12.1.0.1/2 parsing the same query takes 45 seconds.

If we use the hint /*+ optimizer_features_enable('11.2.0.2') */ the parse time is already 8 seconds again.

We would prefer that we do not need this hint.

What can cause this long parse time in Oracle 12?

Any idea?


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