Tuesday May 03, 2016

New Technical Briefs

We've added a new Technical Briefs section to the blog. If you scroll down on the blog you will see a new section titled "Technical Briefs" on the right hand side.

One of the briefs is an update for Oracle Database 12c on how to create SQL Monitor active reports and the other describes how to create an Optimizer trace file. Hopefully you will find these useful quick references.

Monday Apr 18, 2016

Why does BYTES_NOT_POPULATED suddenly show a non-zero value?

I recently got a question from a customer who has just begun adopting Database In-Memory and thought it was worth answering as a blog post in case anyone else had encountered the same scenario and was wondering what was going on.

Here is the question I got:

“I've observed a scenario where a table is fully populated in the In-Memory column store with 0 in the  BYTES_NOT_POPULATED column in v$im_segments, but after some time, the BYTES_NOT_POPULATED column shows a non-zero value. Why is Oracle purging part of my table from memory?”

Let me begin to answer this by assuring you all that Oracle does not purge your data out of the In-Memory column store.

[Read More]

Monday Apr 11, 2016

Oracle OpenWorld 2016 call for papers has begun!

Believe it or not, it's time to start thinking about Oracle OpenWorld 2016!

The Oracle OpenWorld 2016 call for papers is now opens! Oracle customers and partners are encouraged to submit proposals to present at this year's Oracle OpenWorld conference, which will be held September 18 - 22, 2016 at the Moscone Center in San Francisco. Details and submission guidelines are available on the Oracle OpenWorld Call for Papers web site. The deadline for submissions is Friday,  May 9, 11:59 p.m. PDT.

We look forward to checking out your sessions on Oracle Database In-Memory and how it has changed the way you do business!

Friday Mar 25, 2016

Why didn't Database In-Memory improve the performance of my query?

After I posted last weeks blog post on identifying analytic queries that benefit from Database In-Memory, I got the following question, Why didn't Database In-Memory improve the performance of my query?"

I've simplified the query in question down to the following,

SELECT Count(DISTINCT cust_id)
FROM ssh.sales
WHERE amount_sold > 1;

So, why didn’t Database In-Memory improve the performance of this query?

[Read More]

Friday Mar 18, 2016

How do I identify analytic queries that will benefit from Database In-Memory?

Although Database In-Memory can be used in both Enterprise OLTP systems and Data Warehouses, only analytic queries will benefit from accessing data from the In-Memory column store (IM column store). Remember the IM column store enables large volumes of data to be rapidly scanned and processed using a variety of optimizations. Simpler transaction based queries, such as a primary key look up do not benefit from the IM column store and are automatically directed to the buffer cache.

But how do you identify an analytic query?

An analytic query is one where a large amount of data is scanned and filtered to return critical data that drives better business decisions. It doesn’t necessarily mean a query that contains one of Oracle’s analytical functions but they can also see benefits. A star query is a good example of such a query. By star query, I mean a query where a large fact table (center of the star) is joined to a number of smaller dimension tables (the points of the star).

If you don’t have a simple star schema (most people don’t) then you can identify a good candidate query by examining some key characteristics.

[Read More]

Friday Feb 12, 2016

How do I limit the amount of memory each PDB can use in the IM column store?

In case you aren’t familiar with what a PDB is, let me begin by explaining what a Multitenant environment is and how PDBs fit into it.

Oracle Multitenant is a new database consolidation model in Oracle Database 12c in which multiple Pluggable Databases (PDBs) are consolidated within a single Container Database (CDB). While keeping many of the isolation aspects of single databases, Oracle Multitenant allows PDBs to share the system global area (SGA) and background processes of a common CDB.

When used with Oracle Database In-Memory, PDBs also share a single In-Memory column store (IM column store) and hence the question, "How do I control how much memory each PDB can use in the IM column store?"

[Read More]

Friday Nov 20, 2015

What happens to a table In-Memory if one of my RAC nodes goes down?

We’ve written a number of blog posts on how Database In-Memory behaves in a RAC environment but recently we’ve gotten a lot of questions regarding what happens if one of the RAC nodes should fail. So, I thought I would try tackle this question and point out a couple of other interesting aspects of running Database In-Memory on RAC in this post.

Quick Recap

If you recall from part 1 of our RAC series each RAC node has it’s own In-Memory column store (IM column store). When a table is populated into memory in a RAC environment it will be distributed across all of the IM column stores in the cluster. That is to say, a piece of the table will appear in each RAC node.

Let’s take a look at an example using the LINEORDER table, which has 5 million rows in it and is approximately 550MB in size on my 3 node RAC cluster.

[Read More]

Thursday Oct 29, 2015

Day 5 of Oracle OpenWorld 2015 October 29th

It's the last day of Oracle OpenWorld and we have saved the very best for last. So hopefully you are still awake and functioning after the party!

Today, we have a fantastic line up of In-Memory sessions, so grab your coffee and start your last day at our hands-on-lab Oracle Database In-Memory Bootcamp (Session HOL10483) at the slightly later time of 9:30am in the Golden Gate room (25th Floor) at the Hotel Nikko.

If you have already attended our hands on lab, check out our last Database In-Memory technical session Introducing Analytic Views—Bringing Star Queries into the Twenty-First Century (Session CON8742) at 9:30am in Moscone South - room 309. During this session Bud Endress will introduce Analytic Views and describe how they easily transform tables into the next-generation data source for BI applications and Excel Pivot Tables.

Before you head for the airport, don't forget to stop by the Engineered System Showcase to check out the Database In-Memory demo and pick up both an In-Memory bumper sticker and a SQL in Silicon sticker.

We hope you have a safe trip home and we will see you all again next year, when we will have even more great session on Oracle Database In-Memory!

Wednesday Oct 28, 2015

Day 4 of Oracle OpenWorld 2015 October 28th

Thanks to all those who stopped by the demogrounds to chat with the In-Memory developers over the last two days. Remember, today is the last day of the demogrounds, so if you haven't had a chance to stop by yet, do so today. The In-Memory developers will be there from 10:00am until 4pm. This may be your last chance to snag an In-Memory bumper sticker, so don't miss out!

But before you head to the demogrounds why not start your day at our hands-on-lab Oracle Database In-Memory Bootcamp (Session HOL10483) in the Golden Gate room (25th Floor) at the Hotel Nikko. The fun begins bright and early at 8:45 am!

There are also some great technical sessions on today, including your first opportunity to ask questions of production Oracle Database In-Memory customers and see if the technology lives up to the hype. I will be hosting our first Oracle Database In-Memory Customer Panel (Session CON8657) at 1:45pm in Moscone South - room 103. The session will begin with each customer briefly sharing how they are using Oracle Database In-Memory before we dive into an open discussion. I strongly encouraged you to actively participate in this session and pose any questions you may have about Database In-Memory and other alternative solutions considered by the panelists.

Then in the afternoon we have our last customer session on Database In-Memory given by General Mills, How Exadata & Database In-Memory Power Precision Marketing at General Mills (Session CON4292) at 3:00pm in Moscone South - room 254. Mark and Josh from General Mills explain how Oracle Exadata with Oracle Database In-Memory gave them a scalable and reliable platform from which to build a consumer-first data warehouse.

Finally before you rush off to put on your dancing shoes for the appreciation event, we have another great technical session, Oracle Database In-Memory: Under the Hood (Session CON8652) at 4:15pm in Moscone South - room 103 where Tirthankar Lahiri, the VP of Database In-Memory development, will provide an insiders view of the technology underlying Oracle Database In-Memory and give you a sneak peek at what you can expect from Oracle Database In-Memory in our next generation!

Tuesday Oct 27, 2015

Day 3 of Oracle OpenWorld 2015 October 27th

Hopefully you enjoyed yesterday, the first full day of technical sessions at Oracle OpenWorld, and are ready for more today!

First thing this morning at 8:45 am is your second opportunity to attend our hands-on-lab, Oracle Database In-Memory Bootcamp (Session HOL10483) in the Golden Gate room (25th Floor) at the Hotel Nikko. I know it's early but trust me it will be a great way to start your day as it will leave you inspired and energized!

Today we will also give our first two technical sessions. First up is  Best Practices for Getting Started with Oracle Database In-Memory (Session CON6775) at 11:00am, in Moscone South - room 104.

In this session, I'll provide you with a step-by-step guide on how to get started with Oracle Database In-Memory, including advice on when and where you should take advantage of Oracle Database In-Memory. I'll also outlines strategies to help ensure that you get the promised performance boost regardless of your database environment. If you do come to this session, be sure to keep an eye out for this little fellow, as he will be on top of all of the slides with the top tips!

Later in the day we have our 3rd customer session when Dan Huls from AT&T WiFi presents, Oracle Database In-Memory: A Practical Solution (Session CON3087) at 4pm in Moscone South - room 307. Dan will share with you how they implemented Oracle Database In-Memory on a large customer-facing data warehousing system in under two months with little or no changes to their application. He will also provide details on why they chose Oracle Database In-Memory versus a more expensive SAP HANA solution.

Finally Juan Loaiza, EVP of Database Development, will present Oracle Database In-Memory—What’s New and What’s Coming (Session CON8659) at 5:15pm in Moscone South— room 103. In this session Juan will explain in detail what motivated Oracle to develop this new technology and provides a clear understanding of how this unique “dual format” architecture works. He will also give you a sneak preview of what to expect next for Database In-Memory. A definite must see session!

Saturday Sep 12, 2015

Oracle Open World 2015 Time to plan your schedule!

There are only 6 weeks to go until Oracle Open World, the largest gathering of Oracle customers, partners, developers, and technology enthusiasts, which begins on October 25th in San Francisco.

Of course the In-Memory development group will be there and you will have multiple opportunities to meet up with us, in one of our technical sessions, our hands-on-labs or at the Oracle demogrounds.

This year the In-Memory team has 4 technical sessions and there are also 5 excellent customer sessions you shouldn't miss.

[Read More]

Monday Sep 07, 2015

Star Schema Challenge - Part 4

In my previous post Star Schema Challenge - Part 3, I reported the first of the in-memory performance results with 25 users querying the star schema in the In-Memory column store (IM column store). In Star Schema Challenge - Part 3.1 I did the same for the de-normalized fact table in the IM column store.  This serves as a comparison between the row format in-memory (buffer cache) and IM column store. For this comparison I stopped at 25 users because it became clear this was enough users for the row store table.  Now it is time to start working towards 100 concurrent users.

[Read More]

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.

[Read More]

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.

[Read More]

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.

[Read More]

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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