Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 







inmemory_size tips

Oracle Database Tips by Donald BurlesonNovember 7, 2015

I need to understand how the inmemory_size parameter woks in Oracle 12c.  Can you describe the inmemory_size parameter?  How does the inmemory_size parameter work in Oracle?  How does the inmemory_size server as an alternative to the KEEP pool?


Answer:  The inmemory_size parameter is used to define the RAM region available for caching tables in Oracle 12c release 1 and beyond.



There are other inmemory parameters:

SQL> show parameter inmemory

NAME                                TYPE                             VALUE
------------------------------------ --------------------------------- -----
inmemory_clause_default              string
inmemory_force                       string                           DEFAULT
inmemory_max_populate_servers        integer                          1
inmemory_query                       string                           ENABLE
inmemory_size                        big integer                      256G
inmemory_trickle_repopulate_servers_ integer                          1
optimizer_inmemory_aware             boolean                          TRUE


The inmemory_size parameter sets the size of the IM column store in a database instance. The default for inmemory_size =0, which means that IM column storage is not used. This initialization parameter must be set to a non-zero value to enable the IM column store. If the parameter is set to a non-zero value, then the minimum setting is 100M.

In a 12c multitenant environment, the setting for inmemory_size in the root is the setting for the entire multitenant container database (CDB).

The inmemory_size can also be set in each pluggable database (PDB) to limit the maximum size of the IM column store for each PDB. The sum of the PDB values can be less than, equal to, or greater than the CDB value. However, the CDB value is the maximum amount of memory available in the IM column store for the entire CDB, including the root and all of the PDBs.

Unless the inmemory_size is specifically set for a PDB, the PDB inherits the CDB value, which means that the PDB can use all of the available IM column store for the CDB.

Also see  my inmemory tips

Oracle Training from Don Burleson 

The best on site "Oracle training classes" are just a phone call away! You can get personalized Oracle training by Donald Burleson, right at your shop!

Oracle training



Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2020

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster