Friday Aug 28, 2015

Popular Statistics with Database In-Memory

Throughout our previous posts we have mentioned various session level statistics that are available to help identify what is actually going on with Database In-Memory. Since these statistic definitions didn't make it into the Reference manual I was asked recently if there is a list anywhere that defines what these statistics are. Since there isn't I thought I'd post a summary of the popular statistics that we've mentioned in the blog and that you might want to know about.

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Friday Aug 21, 2015

Understanding new In-Memory notes in an execution plan

If you have started to play around with Database In-Memory, chances are you have been examining execution plans to see if the optimizer has chosen to use the In-Memory column store (IM column store) or not. In addition to the execution plan itself, you should also check out the NOTE section under the plan, which contains more information about how a query was executed, such as if dynamic sampling was used during the query optimization.

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Friday Aug 14, 2015

Star Schema Challenge - Part 3.1

In my previous post (Star Schema Challenge – Part 3) I revealed the first of the Database In-Memory results, 25 users querying a 500 million row star schema with tables in the In-Memory column store(IM column store) on a commodity Intel-based server with 60 cores and 1TB of DRAM.

In this post I will reveal the first of the in-memory results for the de-normalized version of the fact table.

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Wednesday Aug 05, 2015

New White Paper on using Database In-Memory with the E-Business Suite Released!

We would like to draw your attention to a new white paper has just been released titled "Using Oracle Database In-Memory with Oracle E-Business Suite".

The white paper details how Database In-Memory works, what the requirements are to use it with the E-Business Suite and works through some use cases and examples.  More details can be found in the My Oracle Support (MOS) Note 2025309.1.

The EBS team worked on hard on this paper and we think it's a great source of information for E-Business customers who want to take advantage of Oracle Database In-Memory. Enjoy the read!

Tuesday Aug 04, 2015

Oracle Database In-Memory on RAC - Part 4

Setting Up Independent In-Memory Column Stores

In previous posts we've talked about how to use RAC services to enable the IM column store to be run on a subset of nodes in a RAC environment. We also mentioned that it is possible, using RAC services and the DUPLICATE sub-clause on engineered systems, to enable rolling patches and upgrades when running the IM column store on a subset of nodes.

In this article we're going to talk about how to set up independent IM column stores on a RAC cluster using services and some database initialization parameters.

But first let's ask and answer the question, why would you want to do this? This might be a good idea if you are trying to enforce application affinity at the node level and don't want to allow inter-instance parallelism.

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Friday Jul 24, 2015

What to do with optimizer statistics when upgrading to 12c to take advantage of Database In-Memory

Before most customers can take advantage of Database In-Memory they will need to navigate the tricky terrain of a database upgrade. One of the most challenging aspects of an upgrade is figuring out how to minimize performance regressions due to execution plan changes.

And if that wasn’t enough to handle, the introduction of Database In-Memory into a 12c environment has the potential to change even more of the execution plans. So, what should you do?

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Tuesday Jul 21, 2015

Oracle Database In-Memory Bundle Patch 10 Released

The latest Bundle Patch for Database In-Memory has been released. The Bundle Patch is 21188742 or 12.1.0.2 Bundle Patch 10 for Engineered Systems and DB In-Memory (July2015)). This Bundle Patch improves the performance of mixed workload environments (OLTP & DW workloads), as well as enhancing the performance of analytic queries with aggregation. More information on the latest Bundle Patch can be found in the MOS note 21188742.8 or in the Mos note: 12.1.0.2 Bundle Patches for Engineered Systems and DB In-Memory (Doc ID 1937782.1).

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Friday Jul 17, 2015

Star Schema Challenge - Part 3

In my previous posts on the Star Schema Challenge, I established baseline results for query performance with row store tables (that is, without using Database In-Memory). A 9 dimensional, 500 million row star schema supported 25 users with a median query time of 16.9 seconds. (With a median of 16.9 seconds, there was not much point in increasing the number of users with the row store tables). The same data in a 500 million row de-normalized table supported 25 users with a median query time of 33.5 seconds per query.

Remember all of these tests are being conducted on a 60 core Intel server with commodity disk and 1 TB of DRAM.

Row Store Query

Median query performance (in seconds) of the query workload with 25 users on row store tables.

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Friday Jul 10, 2015

Star Schema Challenge - Part 2.1

In Star Schema Challenge – Part 2 I revealed baseline results for my query workload running on a 500 million row star schema with all tables marked NO INMEMORY and In-Memory Aggregation prevented using the NO_VECTOR_TRANSFORM hint. With a median of 16.9 seconds per query (allowing for an average think time between queries of 5 seconds), I decided that 25 users were enough for a baseline.

After my first post in this series someone suggested that the best implementation might be a de-normalized table. I decided to satisfy this user’s curiosity and test a de-normalized table also, starting with NO INMEMORY test. (Vector Transform is not applicable to the de-normalized table because it does not join to another table.)

[Read More]

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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Thursday Apr 30, 2015

When to use Oracle Database In-Memory?

At this stage you've probably heard a lot about how Oracle Database In-Memory is an unprecedented breakthrough in Oracle database performance, offering incredible performance gains for a wide range of workloads. What you might not know is when and where it would be best to take advantage of this exciting new technology.

So, we've put together a new whitepaper to share some of the high-level use cases, and explain the scenarios under which Database In-Memory provides a performance benefit. The purpose of this paper is to give you some general guidelines so that you can determine whether your use case is a good match.

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Tuesday Apr 28, 2015

Discussing In-Memory Databases at The HIVE event in Palo Alto on May 6, 2015

If you happen to be in the San Francisco Bay Area on May 6th, you might be interested in checking out a panel discussion on In-Memory Databases brought to you by The HIVE. The discussion is intended to explore use cases for In-Memory Database technologies and the impact of technologies and trends such as flash memory and cloud computing.

The panel will be made up of industry experts from all of the leading In-Memory Database providers including Oracle, IBM, Aerospike, MemSQL and Pivotal. The session will be moderated by Nik Rouda and my boss, Tim Shetler will be representing Oracle. Noticeably absent are SAP (The SAP Sapphire conference is taking place) and Microsoft. Dozens of other smaller vendors no doubt would like to take part, if you buy into their definition of "In-Memory Database". 

So what does it take to qualify as an "In-Memory database"?

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Friday Apr 24, 2015

In-Memory Priority

I'd like to thank everyone who attended our two Hands On Lab sessions at Collaborate last week. We had a great time presenting them and we received some really good feedback. One of the questions that came up, and gets asked periodically, is how does In-Memory priority really work?

Many times people have the misconception that the In-Memory priority attribute affects more than just the order of population but that’s not the case. The only thing the priority affects is the order of population at database startup. We discussed population briefly some time ago, but I think it's worth a quick review.

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Friday Apr 17, 2015

CPU Efficient Query Processing with Database In-Memory

In my last post I talked about In-Memory Aggregation and mentioned that the vector transformation plan is more CPU efficient than alternative plans. In this post I’ll provide a few examples to illustrate just how effective a vector transformation plan can be.

Let’s consider a star schema, with one fact table and 9 dimension tables (time, customer, product, channel and demographic attributes such as age and income).

9 Dimensional Star

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Thursday Apr 09, 2015

Push-Down: Part 2

In our previous post we introduced the concept of push down. The ability to push predicates, aggregations and group-bys down into the scan of a column or columns, allowing Oracle to take full advantage of all the scan performance features of the In-Memory column store. We also illustrated how you could monitor the benefits of push down via session level statistics (v$mystat). What you might not have realized is that we can also see what where clause predicates get push via the execution plan.

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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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