Oracle Exadata Statement of Direction

There is a very interesting paper about the way of direction of the Exadata Database Machine.


Thanks a lot Günther Stürner.

GTT and Smart Scan – the importance of the append hint

While writing the previous two posts about GTTs and Smart Scan, I stumbled across an interesting observation. When I started putting my thoughts to (virtual) paper, I thought it was going to be a short post. Well, it wasn’t to be, again. Anyway, you might find this interesting.

Initial Situation

If you read the previous posts this code example I used to populate the GTT might look familiar:

insert /*+ append */ into gtt select  (more...)

Exadata GI Upgrade to + PSU Jul2016


Recently I did a upgrade to Grid Infrastructure on a few Exadata Clusters

Here my summary of the installation

Before you start please read the following MOS note 1681467.1. This note is very helpful and describes the whole procedure in a Exadata environment

It’s not only the Upgrade to In the same „session“ I also install the GI PSU Jul 2016 and the Oneoff Patch (more...)

Smart Scanning GTTs – what about Flash Cache?

Continuing the example of the previous blog post (is it possible to Smart Scan GTTs?), I am investigating if Smart Scans against GTTs can benefit from Flash Cache, or “optimised reads”. The easiest way to see this in your session is to calculate the change in session counters based on v$mystat or v$sesstat. Other tools might also provide information about the amount of data read from Flash Cache, but there are quite often extra (more...)

Exadata migration

Had a wonderful Sangam16 conference in India, and received much applaud for the two presentations delivered,  Oracle 12c multitenancy and Exadata migration best practices.

After a very short trip to India, life started to be business as usual again, and become busy. Was fully occupied with multiple assignments: Oracle EBS database health check assessment at a client for 2 days, GI/RDBMS/PSU deployments on Oracle Sun Super Cluster M7, Exadata configuration preparation and 9 databases migration (more...)

Little things worth knowing: Can I Smart Scan a Global Temporary Table?

A question that has come up while preparing to deliver another Exadata Optimisation Class is whether you can offload queries against Global Temporary Tables (GTT) or not. There are subtle differences between heap tables and GTTs such as how statistics are handled and where they are stored that merit a little investigation.

I have used the lab environment on the X3-2 (Exadata, RDBMS) to test (more...)

Advanced Oracle memory profiling using pin tool ‘pinatrace’

In my previous post, I introduced Intel Pin. If you are new to pin, please follow this link to my previous post on how to set it up and how to run it.

One of the things you can do with Pin, is profile memory access. Profiling memory access using the pin tool ‘pinatrace’ is done in the following way:

$ cd ~/pin/pin-3.0-76991-gcc-linux
$ ./pin -pid 12284 -t source/tools/SimpleExamples/obj-intel64/

The pid is (more...)

Introduction to Intel Pin

This blogpost is an introduction to Intel’s Pin dynamic instrumentation framework. Pin and the pintools were brought to my attention by Mahmoud Hatem in his blogpost Tracing Memory access of an oracle process: Intel PinTools. The Pin framework provides an API that abstracts instruction-set specifics (on the CPU layer). Because this is a dynamic binary instrumentation tool, it requires no recompiling of source code. This means we can use it with programs like the Oracle (more...)

Redo a blogpost

This blogpost is about the Oracle redo log structures and redo efficiency in modern Oracle databases. Actually, a lot of subtle things changed surrounding redo (starting from Oracle 10 actually) which have gone fairly unnoticed. One thing the changes have gone unnoticed for is the Oracle documentation, the description of redo in it is an accurate description for Oracle 9, not how it is working in Oracle 10 or today in Oracle 12.1.0. (more...)

Smart Scans efficiency chart for Oracle Engineered Systems

If you manage an Oracle Engineered System you may wonder how well your Smart Scans are performing. Are you taking full advantage of Exadata Optimizations? If so, how do you measure them?

Uwe Hesse explains well some important statistics on Exadata. For some time now, eDB360 includes a report on Smart Scan efficiency, which is nothing but a Google Chart on top of relevant statistics.

Sample chart below is from a data warehouse DW application. It (more...)

DOAG Konferenz 2016

| Nov 5, 2016


Noch eine Woche und ein paar Tage dann startet die DOAG Konferenz 2016.

Es warten viele Interessante Themen rund um das Thema Oracle.

Einfach mal über den Link ins Vortragsprogramm schauen.



Exadata memory configuration

Read this post if your Exadata compute nodes have 512/768GB of RAM or you plan to upgrade to the same.

There has been a lot of information about hugepages and I wouldn’t go into too much details. For efficiency, the (x86) CPU allocates RAM by chunks (pages) of 4K bytes and those pages can be swapped to disk. For example, if your SGA allocates 32GB this will take 8388608 pages and given that Page Table (more...)

A technical security analysis of the snmp daemon on Exadata

Recently I was asked to analyse the security impact of the snmp daemon on a recent Exadata. This system was running Exadata image version This blog article gives you an overview of a lot of the things that surround snmp and security.

First of all what packages are installed doing something with snmp? A list can be obtained the following way:

# rpm -qa | grep snmp
net-snmp-utils-5.5-54.0. (more...)

Conjuctive Normal Form

I recently tweeted about a comment I’d picked up at the Trivadis performance days regarding tablescans and performance.

“If you can write your SQL in conjunctive normal form it can help the optimizer to offload more predicates”

Inevitably someone asked me if I had an example to demonstrate this – I didn’t, and still don’t really, but here’s an interesting demo based on an example from the Oracle In-Memory blog showing how the optimizer will (more...)

OTN Appreciation Day:

In the wake of the great hospitality shown by the OTN crew at Open World, Tim Hall thought that getting the community together for a series of “OTN appreciation” blogs would be a good way to show our thanks back.

Thinking about tools provided by Oracle that make my life easier, my mind went to  This tool helps automate many of the tedious tasks that must be performed when performing an OS update on an Exadata compute (more...)

How to enable Exadata Write-Back Flash Cache

Yes, this is well-known and the process has been described in Exadata Write-Back Flash Cache – FAQ (Doc ID 1500257.1) but what the note fails to make clear is that you do NOT have to restart cell services anymore hence resync the griddisks!

I had to enable the WBFC many times before and every time I’d restart the cell services, as note suggests. Well, this is not required anymore, starting with 11.2.3. (more...)

Extending an Exadata Eighth Rack to a Quarter Rack

In the past year I’ve done a lot of Exadata deployments and probably half of them were eighth racks. It’s one of those temporary things – let’s do it now but we’ll change it later. It’s the same with the upgrades – I’ve never seen anyone doing an upgrade from an eighth rack to a quarter. However, a month ago one of our customers asked me to upgrade their three X5-2 HC 4TB units from (more...)

OOW 2016 fünfter und letzter Tag

| Sep 22, 2016

Die Zeit geht schneller vorbei als man denkt. Heute ist bereits der letzte Tag der OOW 2016.

Auf der Agenda stand ein Meeting mit Gurmeet Goindi vom Exadata Produktmanagement.

Wir haben die Topics für die DOAG Konferenz besprochen:

  • Treffen mit der Arbeitsgruppe Engineered Systems in Nürnberg am Vorabend der Konferenz
  • Präsentation von Gurmeet
  • Unconference Session

Gurneet legt besonderen Wert darauf, die offenen Fragen der Community in Deutschland zu beantworten. Ich freue mich sehr Ihn im (more...)

OOW 2016 zweiter Tag

| Sep 19, 2016


Tag zwei auf der OpenWorld in San Francisco. Es beginnt mit dem Vortrag von Andy Mendelsohn

The World’s #1 Database for the Cloud

Die wesentlichen Aussagen des Vortrags zur Oracle Release 12.2

  • In Memory Technologie wird die Zukunft sein, also die Datenbank verlagert sich „from Disk to Memory“
    • Ein Highlight In-Memory läuft mit Active Data Guard auf einer Standby Datenbank
  • Transformation
    • Data Warehouse Technologie „bewegt“ sich in Richtung BigData (Plattform)
  • From OnPremise in „Richtung“ (more...)

Upgrade yourself from DBA to DMA

In any profession, learning never ends. From my very personal perspective and own exprience, I strongly beleinv in one who upgrade his skills always stays a step ahead from the rest. To stay competitive, it is necessary to upgrade our skills according the market demand.

For DBA folks who aim and dream to learn and upgrade their knwoledge with Oracle Exadata technologies, I wrote a 5 series article to Toad, below are the links to (more...)