SGA_MAX_SIZE & SGA_TARGET / MEMORY_TARGET & MEMORY_MAX_TARGET

Posted on by Osama Mustafa in Database
In this article i will discuss the Difference between these parameter and how to use them ,  MEMORY_TARGET & MEMORY_MAX_TARGET  parameters appear in 11g .

I will depend on oracle documentation to describe these parameter :

SGA_MAX_SIZE sets the overall amount of memory the SGA can consume but is not dynamic.

The SGA_MAX_SIZE parameter is the max allowable size to resize the SGA Memory area parameters. If the SGA_TARGET is set to some value then the Automatic Shared Memory Management (ASMM) is enabled, the SGA_TARGET value can be adjusted up to the SGA_MAX_SIZE parameter, not more than SGA_MAX_SIZE parameter value.

MEMORY_TARGET & MEMORY_MAX_TARGET 

you can manage SGA and PGA together rather than managing them separately.

If you set SGA_TARGET, SGA_MAX_SIZE and PGA_AGGREGATE_TARGET to 0 and set MEMORY_TARGET (and optionally MEMORY_MAX_TARGET) to non zero value, Oracle will manage both SGA components and PGA together within the limit specified by you.

If MEMORY_TARGET is set to 1024MB, Oracle will manage SGA and PGA components within itself.

If MEMORY_TARGET is set to non zero value:

  • SGA_TARGET, SGA_MAX_SIZE and PGA_AGGREGATE_TARGET are set to 0, 60% of memory mentioned in MEMORY_TARGET is allocated to SGA and rest 40% is kept for PGA.
  • SGA_TARGET and PGA_AGGREGATE_TARGET are set to non-zero values, these values will be considered minimum values.
  • SGA_TARGET is set to non zero value and PGA_AGGREGATE_TARGET is not set. Still these values will be autotuned and PGA_AGGREGATE_TARGET will be initialized with value of (MEMORY_TARGET-SGA_TARGET).
  • PGA_AGGREGATE_TARGET is set and SGA_TARGET is not set. Still both parameters will be autotunes. SGA_TARGET will be initialized to a value of (MEMORY_TARGET-PGA_AGGREGATE_TARGET).

You can have some Description  On http://support.oracle.com

 Thank you
Osama Mustafa

Published by Osama Mustafa

Osama considered as one of the leaders in Cloud technology, DevOps and database in the Middle-East. I have more than ten years of experience within the industry. moreover, certfied 4x AWS , 4x Azure and 6x OCI, have also obtained database certifications for multiple providers. In addition to having experience with Oracle database and Oracle products, such as middle-ware, OID, OAM and OIM, I have gained substantial knowledge with different databases. Currently, I am architecting and implementing Cloud and DevOps. On top of that, I'm providing solutions for companies that allow them to implement the solutions and to follow the best practices.

16 thoughts on “SGA_MAX_SIZE & SGA_TARGET / MEMORY_TARGET & MEMORY_MAX_TARGET”

  3. Excellent article, thanks for explanation, I have question on how to calculate value for MEMORY_TARGET, my S.O. is oracle linux with 64GB memory, only running is database.help me, pleaseregards[AZ]

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