SELECT from DBA_EXTENTS is Slow With OPTIMIZER_MODE=FIRST_ROWS
(Doc ID 1471558.1)
Last updated on OCTOBER 30, 2019
Applies to:Oracle Database - Enterprise Edition - Version 184.108.40.206 to 220.127.116.11 [Release 11.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.
A tkprof on a produced 10046 trace file shows a full table scan on X$KTFBUE with many "db file sequential reads" as the main contributor to the query response time:
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