Thanks for the question, Steve.
Asked: December 14, 2017 - 12:25 pm UTC
Last updated: December 15, 2017 - 7:21 am UTC
Version: 12.2.0.1.0
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Hi,
We are noticing this wait event (acknowledge over PGA limit) at the top after upgrade from 11g to 12c. We have already tried the workaround to set PGA_TARGET_AGGREGATE to 0 and this wait event still comes up at the top. Is this a problem to have this wait event at the top 3 foreground wait event *always* in the AWR report?
It comes under a "Scheduler" class wait event, so this is probably a problem as it means the database is doing more time scheduling related stuff rather than the useful CPU or I/O stuff, right? I am concerned if our database is performing optimally or not because of this and sometimes we face severe performance issues. Any pointer is much appreciated.
Thanks,
Steve.
and Connor said...
Check MOS note 2138882.1
"PGA_TARGET_AGGREGATE = 0" is not what you want to do. Your options are:
(1) Increasing PGA_AGGREGATE_TARGET.
(2) Increasing PROCESSES parameter.
(3) Setting underscore parameter "_pga_limit_target_perc" to a value greater than the default value.
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