Using the APM Database without APM CE (CEM ) creates large empty data partitions.

Document ID : KB000048178
Last Modified Date : 14/02/2018
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Description:

Note that this applies ONLY applies when the following three conditions are met:

  1. APM CE (CEM) is not deployed. So the APM database is only being used for triage map operations.

  2. The APM database is using Oracle version 11gR2 and later.

  3. There is a need to save disk space instead of creating empty partitions

Solution:

If wanting to save disk space instead of creating empty partitions and meeting above conditions, then do the following:

Step1: Create the Oracle User

Step2: Execute the following SQL Query: ALTER SYSTEM SET deferred_segment_creation=FALSE scope=both

Step3: Create the APM schema using the EM installer

Step4: Execute the following SQL Query: ALTER SYSTEM SET deferred_segment_creation=TRUE scope=both

Step5: Start the Cluster. There will be no empty partitions created. A partition is created only when data is inserted.

Reference:

http://oradbastuff.blogspot.in/2011/04/initial-extent-size-of-partition.html

Note:

Setting the "_partition_large_extents" property may help create smaller size extents less than 8MB. (Values can start from 64k) and save Oracle disk space by reducing the partition size. But this may turn out to increase performance overhead if enabling APM CE (CEM) in future. This is because the result would end up creating many smaller extents.