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Oracle Database In-Memory Option (DBIM) Basics and Interaction with Data Warehousing Features (Doc ID 1903683.1)

Last updated on JULY 27, 2022

Applies to:

Oracle Database Cloud Service - Version N/A and later
Oracle Database - Enterprise Edition - Version and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database Cloud Machine) - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Information in this document applies to any platform.


This note references some basic information from the Oracle® Database Administrator's Guide 12c Release 1 (12.1) about the Oracle Database In-Memory (IM) column store and adds some information regarding its interaction with various data warehousing features.

Questions and Answers

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In this Document
Questions and Answers
 1.  What patches are required for Database In-Memory?
 2.  Where can I find information about how the IM column store works?
 3.  How do I enable/disable the IM column store, and what is the minimum size? 
 4.  Will objects age out of the IM column store, and can I increase the size of the IM column store dynamically?
 5.  What objects can I put in the IM column store?  
 6.  When will an object benefit from being in the IM column store?
 7.  When will an object not benefit from being in the IM column store?
 8.  How do I populate the IM column store?
 9.  How should I adjust SGA_TARGET and PGA_TARGET when using the IM column store?
 10. How can I estimate how much memory I need to allocate for each object I want to put in the IM column store?
 11. Is the IM column store transactionally consistent with the buffer cache?  
 12. Is IM column store compression the same as Advanced Compression?
 13.. How is DML handled?
 12.2 New Features
 18.1 New Features
 1. I do not have a license for the DBIM option.  How do I demonstrate it is not in use in my database in case of audit?
 1. Is there an Advisor for the IM column store?
 2. How can I monitor the contents of the IM column store?
 Advanced Compression
 1. What happens if data on disk is compressed with either Basic or Advanced Compression?
 Data Pump (non-TTS)
 1. Will objects be imported with the INMEMORY attribute?
 Information Lifecycle Management - Automatic Data Optimization (ADO)
 Materialized Views
 1. Can I put my materialized view logs in the IM column store?  
 1. Should I set the INMEMORY_SIZE parameter at the PDB level, as well as at the CDB level?
 Optimizer and Plan Operations
 1. My table is in the IM column store, so why do I see primary key (PK) access instead of TABLE ACCESS IN MEMORY FULL?
 Parallel Execution
 1. Will parallel execution work with the IM column store?
 1. If only some of my partitions of a partitioned table are in the IM column store, will the IM column store be used? 
 2. If I exchange partitions with a partitioned table that is INMEMORY, will the table that was exchanged into the partition be in the IM column store?
 3. If you want to be able to define at the partition level what columns will or won't be in the column store, how can this be done?  For example, column1 in partition 1 might be INMEMORY, but column1 might not be INMEMORY for partition 2.
 Query Rewrite
 1. If I have my primary (source) tables in the IM column store, will my query still rewrite using my materialized views?
 1. How is the IM column store distributed in a RAC environment?
 Transportable Tablespaces (TTS)
 1.  Is there anything special that needs to be done to use TTS when a tablespace or its objects have the physical attribute of INMEMORY?
 Wrong Results
 1. If have wrong results, how can I narrow down the problem to confirm or eliminate the IM column store as a factor?
  Automatic In-Memory, External Table Support and Greater Performance in Oracle Database 18c
 In-Memory Dynamic Scans

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