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Oracle database operating system memory allocation management for PGA

This post is about memory management on the operating system level of an Oracle database. The first question that might pop in your head is: isn’t this a solved problem? The answer is: yes, if you use Oracle’s AMM (Automatic Memory Management) feature, which let’s you set a limit for the Oracle datababase’s two main memory area’s: SGA and PGA. But in my opinion any serious, real life, usage of an Oracle database on Linux will be (severely) constrained in performance because of the lack of huge pages with AMM, and I personally witnessed very strange behaviour and process deaths with the AMM feature and high demand for memory.


There is a new default in town. Mark my words, you will encounter the following during your 12c life-cycle… From the Oracle 12c Reference manual PGA_AGGREGATE_LIMIT: PGA_AGGREGATE_LIMIT PGA_AGGREGATE_LIMIT specifies a limit on the aggregate PGA memory consumed by the instance. There is no difference in behavior between PGA_AGGREGATE_LIMIT being explicitly set or being set to