Friday Jul 22, 2016

New In-Memory Advisor Version Available

A new version of the Oracle Database In-Memory Advisor has been released. The In-Memory Advisor is designed to help identify analytic processing that may benefit from the use of Oracle Database In-Memory. It supports Oracle Database 11.2.0.3 and later so you don't have to upgrade to Oracle Database 12c to try it out. The new version includes a number of enhancements including an enhanced and simplified script to run the Advisor and get recommendations.

You can get more information about the In-Memory Advisor here.


Friday Jun 17, 2016

Questions You Asked: Can I force a query to use the IM column store?

I was recently asked by a customer, "is it possible to force a query to use the In-Memory column store?" and I thought it would be a good idea to share the answer here on the blog.

The first thing that comes to mind when you starting thinking about forcing how the Oracle Database will execute a query is Optimizer hints. There is an INMEMORY hint available, but that hint just enables the use of the In-Memory column store (IM column store) if the INMEMORY_QUERY parameter has been set to DISABLE (default is ENABLE). If we look closer at the documentation for the hint, we see that it says "This hint does not instruct the optimizer to perform a full table scan. If a full table scan is desired, then also specify the "FULL hint".

So it appears that the answer is that you have to use the FULL hint to ensure that the access method is a full table scan which is a requirement for accessing the IM column store. If the INMEMORY_QUERY has been set to DISABLE then you would also need to use the INMEMORY hint. Of course this also assumes that the IM column store has been enabled and that the object has been enabled for in-memory.


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Friday May 08, 2015

Getting started with Oracle Database In-Memory Part V - Controlling Access

I’m finally going to make good on a promise I made way back in part 3 of our getting started with In-Memory series, to explain how you could control which queries use the In-Memory column store (IM column store) and which don't.

As with all new query performances enhancing features in the Oracle Database, a number of initialization parameters and hints have been introduce that enable you to control when and how the IM column store will be used. This post provides information on the initialization parameter, while the details on the Optimizer hint that control the use of the IM column store can be found on the Optimizer blog.

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Monday Feb 16, 2015

Getting started with Oracle Database In-Memory Part V - Aggregation

When most people think about Oracle Database In-Memory (Database In-Memory), the first thing that comes to mind is super fast scanning and filtering operations. But what you may not know is Database In-Memory also includes many SQL optimizations designed to accelerate star and snowflake type queries. We refer to this collection of SQL optimizations as In-Memory Aggregation (IMA). IMA is typically 3-10x faster than ‘conventional’ plans, and that’s in addition to the improvements provided by scanning and filtering the data via the In-Memory column store (IM column store).

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The Oracle Database In-Memory blog is written by the Oracle product management team and sheds light on all things In-Memory.

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