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"Access" and "Filter" changes when upgraded to 12c

edited Nov 14, 2018 4:39AM in SQL Performance (MOSC) 7 commentsAnswered ✓


we recently upgraded the database from to and - one of the critical sql was running slow.

Upon analysis found - The reason for the slowness is the “Access” and “Filter” Part changes in the explain plan.

When OFE set to – the predicate information shows both Access and Filter – and this sql is running for more than 10 min

BTW – this table has a composite PK with this order C1,C2,C3,C4 – out of all these columns, NDV for C3 column is very high, close to the number of rows in the table, rest other columns (C1,C2,C4) has NDV < 10  and num of rows in this table is around 500M .

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