Adjusting Segment Growth with MAXEXTENTS in Oracle Database

calendar Feb 1, 2024 / · 2 min read · database-administration oracle tablespace segments dba_segments  ·
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Alters The MAXEXTENTS Parameter For A Specific Database Segment

Sample SQL Command

1alter <segment_type> <segment_name> storage(maxextents 150);
2/

Purpose:

  • To define the maximum number of extents the segment can occupy, controlling its potential growth and space allocation behavior.

Breakdown:

  1. alter <segment_type> <segment_name>: This clause initiates the alteration process, specifying the type (e.g.,TABLE,INDEX) and name of the segment.
  2. storage(maxextents 150): This subclause defines the new maxextents value to 150. You can replace this with your desired number of extents.

Key Points:

  • This code requires DBA or SYSDBA privileges to execute.
  • Ensure the specified segment exists and the new maxextents value is valid (positive integer) and aligns with available space and growth expectations.
  • Increasing maxextents allows more space for growth but doesn't automatically allocate it. Monitor space usage to avoid exhaustion even with higher limits.
  • Reducing maxextents can limit growth but might lead to errors if the segment already exceeds the new limit. Analyze usage carefully before lowering it.
  • Consider using UNLIMITED for maxextents to allow automatic growth, but be aware of potential performance or space management implications.

Insights and Explanations:

  • Adjusting maxextents is a manual space management technique. Regularly review and adjust segment extents based on data volume, growth patterns, and performance considerations.
  • Alternative space management options like automatic segment space management (ASSM) can automate extent allocation and simplify management.
  • Understanding the interplay between maxextents, allocated space, and segment growth is crucial for effective space optimization and preventing unexpected issues.

Remember to use this code responsibly, assess potential impacts, and adjust the segment name and maxextents value according to your specific database needs and space management strategy.

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