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SMON - Temporary Segment Cleanup and Free Space Coalescing (Doc ID 61997.1)

Last updated on JANUARY 09, 2023

Applies to:

Oracle Database - Enterprise Edition - Version and later
Information in this document applies to any platform.


SMON - Temporary Segment Cleanup and Free Space Coalescing in Oracle 7.3 and Higher


  Since the introduction of the unlimited extents feature in Oracle 7.3, it is
  possible for SMON to have to either clean up a large number of temporary
  extents, or to coalesce a large number of free extents. This can manifest
  itself by SMON appearing to spin, consuming a high percentage of CPU for
  long periods. This article explains what is happening, and what (if
  anything) can be done.

  The discussion concentrates mainly on non-TEMPORARY type tablespaces. There
  is however a section at the end of the article which discusses possible
  issues with tablespaces of type TEMPORARY.

Coalescing free space is not necessary for locally managed tablespaces because bitmaps automatically track adjacent free space.
Please refer to:
  Oracle9i Database Administrator's Guide
  Release 2 (9.2)
  Part Number A96521-01
  Chapter 11 - Managing Tablespaces

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