ORA-04030: out of process memory when trying to allocate NNNN bytes errors in BG Log file.

Document ID : KB000051406
Last Modified Date : 14/02/2018
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The reason that this error is present in the BG log file is due to an unpublished Oracle bug 6471770.

The scenario can be due to large data sets that cause allocated hash group-bys to allocate memory beyond internal limit for the auto-memory manager of PGA.


Please follow these steps to resolve the issue:

  1. Backup your Oracle instance and verify the integrity of the backup.

  2. Login to SQL PLUS as an administrative account.

  3. Enter the following command: alter system set "_gby_hash_aggregation_enabled"=false scope=both;

  4. As an alternative you can use "NO_USE_HASH_AGGREGATION" hint within the SQL statement to avoid this issue.

  5. This issue is resolved in the following patchsets from Oracle: Oracle or Oracle