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High Wait Event "Acknowledge Over PGA Limit" Though Allocated PGA Doesn't Reach PGA_AGGREGATE_LIMIT (Doc ID 2437003.1)

Last updated on FEBRUARY 02, 2021

Applies to:

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


The AWR or Statspack reports show high wait event "Acknowledge Over PGA Limit", also sessions are actually waiting for this event and performance is affected.
The "Acknowlege Over PGA limit" is a new wait event that was introduced with PGA_AGGREGATE_LIMIT in 12.1, and it will force a process that wants more PGA to wait a bit if the instance is getting close to hitting the limit.
If allocated PGA is close to PGA_AGGREGATE_LIMIT, it is an expected behavior. Reference: Doc ID 2138882.1.

The wait event can be encountered also when PGA allocation is less than PGA_AGGREGATE_LIMIT.




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