PGA_AGGREGATE_LIMIT

MGA Issue – and it is fixed with Oracle 19.8.0 and newer

Posted on August 20, 2020 by ASM / RAC / GI Flaws and Pitfalls 6

Where do I start? One of the customer accounts I worked the longest time with recently upgraded to Oracle 19c on Exadata. They are an Exadata customer since 2009. After going live on 19c, a few days later they hit an MGA Issue – and it is fixed with Oracle 19.8.0 and newer. But question no.1 was: Why hasn’t Oracle warned us – and how could we have learned about it?

MGA Issue - and it is fixed with Oracle 19.8.0 and newer

Photo by Scott Webb on Unsplash

What is the MGA?

OK, I have heard of SGA and PGA. But MGA? The first two hits when I search with …

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PGA_AGGREGATE_LIMIT enforces default since Oracle Database 12.2.0.1

Posted on May 4, 2017 by Behavior Change Oracle Database 12.2.0.1 Parameters 11

The init.ora/spfile parameter PGA_AGGREGATE_LIMIT got introduced in Oracle Database 12.1.0.1.

As per documentation in Oracle Database 12.1 it got defined as:

“PGA_AGGREGATE_LIMIT specifies a limit on the aggregate PGA memory consumed by the instance.“.

Furthermore the algorithm for its setting got described as:

“By default, PGA_AGGREGATE_LIMIT is set to the greater of 2 GB, 200% of PGA_AGGREGATE_TARGET, and 3 MB times the PROCESSES parameter. It will be set below 200% of PGA_AGGREGATE_TARGET if it is larger than 90% of the physical memory size minus the total SGA size, but not below 100% of PGA_AGGREGATE_TARGET.”

Default

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Mike Dietrich
Oracle Senior Director of Product Manager for Database Upgrade, Migrations and Patching writing just another blog.

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