Exadata Documentation Available

Please join me in welcoming the Exadata product documentation to the internet. It’s been a long time coming, but glad it’s finally made an appearance!

Exadata X5 – A Practical Point of View of the New Hardware and Licensing

Oracle recently announced its latest iteration of Exadata – X5-2. It includes a refresh of the hardware to the most recent Xeon® E5-2699 v3 CPUs. These new CPUs boost the total cores count in a full rack to 288. This is higher than the current 8 socket “big machine” version X4-8, which has only 240 cores.

But the most exciting part is the all flash version of Exadata. In the previous generation – X4 – (more...)

Understanding enhancements to block cleanouts in Exadata part 2

In part 1 of the series I tried to explain (probably a bit too verbose when it came to session statistics) what the effect is of delayed block cleanout and buffered I/O. In the final example the “dirty” blocks on disk have been cleaned out in the buffer cache, greatly reducing the amount of work to be done when reading them.

Catching up with now, and direct path reads. You probably noticed that the migration (more...)

Understanding enhancements to block cleanouts in Exadata part 1

Travel time is writing time and I have the perfect setting for a techie post. Actually I got quite excited about the subject causing the article to get a bit longer than initially anticipated. In this part you can read about block cleanouts when using buffered I/O. The next part will show how this works using direct path reads and Smart Scans.

The article ultimately aims at describing the enhancements Exadata brings to the table (more...)

Exadata 12c New Features RMOUG Slides

I've finally gotten around to post my RMOUG Slide Deck on Slideshare. Hopefully this is helpful to folks looking at new features in Exadata.

Exadata & In-Memory Real World Performance Artikel (German)

Heute wurde auf "informatik-aktuell.de" ein aktueller Artikel von mir veröffentlicht. Es geht darin um die Analyse eines Falles bei einem meiner Kunden, der auf Exadata nicht die erwartete Performance erreicht hat.

In dem Artikel werden unterschiedliche Abfrage-Profile analysiert und erklärt, wie diese unterschiedlichen Profile die speziellen Features von Exadata und In-Memory beeinflussen.

Teil 1 des Artikels
Teil 2 des Artikels

Oracle Exadata X5: The Road To Ten Billion Dollars


Now that the dust has settled on the announcement of Oracle’s new Exadata X5 Database Machine, I’ve been doing some research in order to update my History of Exadata post (it’ll be ready soon). While reviewing the datasheets and other collateral for the X5 I was struck by the meteoric increase in one particular statistic: the number of processor cores on each database server. Oracle is riding that Moore’s Law train all the way to the bank.


How Can I Compress Thee

“You can swim all day in the Sea of Knowledge and not get wet.” 
― Norton Juster, The Phantom Tollbooth 

In previous posts compression options have been discussed, and now it’s time to see how Oracle performs basic compression. It isn’t really compression, it’e de-duplication, but it does result in space savings for data that won’t be modified after it’s ‘compressed’. Let’s look at how Oracle saves space with your data.

Oracle de-duplicates the (more...)

Changed licensing rules for Exadata X5-2 with OracleVM

On 21 January 2015, Oracle announced Exadata X5, the sixth revision of Oracle’s database management system (DBMS) engineered system.

The entire Exadata configuration no longer needs to be licensed when using OracleVM. Instead, a minimum of 40% of the cores in a server must be licensed. This information has been published in an update of the partitioning document.

Gartner wrote a blogpost about this.

The purpose of  this blogpost in front of you is just (more...)

Free Webinar "Oracle Exadata & In-Memory Real-World Performance"

It's webinar time again.

Join me on Wednesday, January 28th at AllThingsOracle.com for a session based on a real world customer experience.

The session starts at 3pm UK (16:00 Central European) time. The webinar is totally free and the recording will made available afterwards.

Here's the link to the official landing page where you can register and below is the official abstract:


After a short introduction into what the Oracle Exadata Database Machine (more...)

Want to learn Exadata ?

Many people have asked me this question that how they can learn Exadata ? It starts sounding even more difficult as a lot of people don’t have access to Exadata environments. So thought about writing a small post on the same.

It actually is not as difficult as it sounds. There are a lot of really good resources available from where you can learn about Exadata architecture and the things that work differently from any non-Exadata (more...)

OLTP type 64 compression and ‘enq: TX – allocate ITL entry’ on Exadata

Recently we’ve seen a strange problem with the deadlocks at the client database on Exadata, Oracle version . Wait events analysis showed that sessions were waiting for “enq: TX – allocate ITL entry” event. It was strange because there are at most two sessions making DMLs and at least two ITL slots are available in the affected tables blocks. I made some block dumps and found that affected blocks contain the OLTP-compressed (more...)

Reading Oracle memory dumps

Every DBA working with the Oracle database must have seen memory dumps in tracefiles. It is present in ORA-600 (internal error) ORA-7445 (operating system error), system state dumps, process state dumps and a lot of other dumps.

This is how it looks likes:

Dump of memory from 0x00007F06BF9A9E00 to 0x00007F06BF9ADE00
7F06BF9A9E00 0000C215 0000001F 00000CC1 0401FFFF  [................]
7F06BF9A9E10 000032F3 00010003 00000002 442B0000  [.2............+D]
7F06BF9A9E20 2F415441 31323156 4F2F3230 4E494C4E  [ATA/V12102/ONLIN]
7F06BF9A9E30 474F4C45 6F72672F 315F7075  (more...)

Oracle Bundle Patching

I’ve spent a few days playing with patching with the so called “Database Patch for Engineered Systems and Database In-Memory”. Lets skip over why these not necessarily related feature sets should be bundled together into effectively a Bundle Patch.

First I was testing going from to BP2 or Then as soon as I’d done that of course BP3 was released.

So (more...)

Oracle database operating system memory allocation management for PGA – part 4: Oracle and AMM

This is the 4th post in a series of posts on PGA behaviour of Oracle. Earlier posts are: here (PGA limiting for Oracle 12), here (PGA limiting for Oracle 11.2) and the quiz on using PGA with AMM, into which this blogpost dives deeper.

As laid out in the quiz blogpost, I have a database with the following specifics:
-Oracle Linux x86_64 6u6.
-Oracle database PSU 4
-Oracle (more...)

Oracle database operating system memory allocation management for PGA – part 3: Oracle and AMM: Quiz

This is a series of blogposts on how the Oracle database makes use of PGA. Earlier posts can be found here (PGA limiting for Oracle 12) and here (PGA limiting for Oracle 11.2).

Today a little wednesday fun: a quiz.

What do you think will happen in the following situation:

-Oracle Linux x86_64 6u6.
-Oracle database PSU 4
-Oracle database (single instance) with the following parameter set: memory_target=1G. No other (more...)

Oracle database operating system memory allocation management for PGA – part 2: Oracle 11.2

This is the second part of a series of blogpost on Oracle database PGA usage. See the first part here. The first part described SGA and PGA usage, their distinction (SGA being static, PGA being variable), the problem (no limitation for PGA allocations outside of sort, hash and bitmap memory), a resolution for Oracle 12 (PGA_AGGREGATE_LIMIT), and some specifics about that (it doesn’t look like a very hard limit).

But this leaves out Oracle version (more...)

Oracle database operating system memory allocation management for PGA

This post is about memory management on the operating system level of an Oracle database. The first question that might pop in your head is: isn’t this a solved problem? The answer is: yes, if you use Oracle’s AMM (Automatic Memory Management) feature, which let’s you set a limit for the Oracle datababase’s two main memory area’s: SGA and PGA. But in my opinion any serious, real life, usage of an Oracle database on Linux (more...)

UKOUG Tech14 slides – Exadata Security Best Practices

I think 2 years is long enough to wait between posts!

Today I delivered a session about Oracle Exadata Database Machine Best Practices and promised to post the slides for it (though no one asked about them :). I’ve also posted them to the Tech14 agenda as well.

Direct download: UKOUG Tech14 Exadata Security slides

The Importance of the In-Memory DUPLICATE Clause for a RAC System

With the INMEMORY clause you can specify 4 sub-clauses:

  • The MEMCOMPRESS clause specifies whether and how compression is used
  • The PRIORITY clause specifies the priority (“order”) in which the segments are loaded when the IMCS is populated
  • The DISTRIBUTE clause specifies how data is distributed across RAC instances
  • The DUPLICATE clause specifies whether and how data is duplicated across RAC instances

The aim of this post is not to describe these attribues in detail. Instead, (more...)