HPC versus HDFS: Scientific versus Social

There have been rumblings from the HPC community indicating a general suspicion of and disdain for Big Data technology which would lead one to believe that whatever Google, Facebook and Twitter do with their supercomputers is not important enough to warrant seriousness—that social supercomputing is simply not worthy.  A little of this emotion seems to […]

Oracle Real World Performance

Great videos on Oracle Real World Performance.


RAC, 12c and Direct Path Reads

Yes, direct path reads again :) No worries I’m already a bit bored from digging in this algorithm, so I think this is going to be my last post about it. Till they change it again of course. And yes, in 12.1.0.2 they did. For introduction to DPR, you can check my previous post, because […]

Oracle OpenWorld 2014 – An OakTable World picture presentation

Oracle OpenWorld 2014 – Datatype context…?!

The native JSON database functionality presentations are done. If you want to experience first hand what you can do with those new operators during Oracle...

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Review: "Java EE 7 Performance Tuning and Optimization" by Osama Oransa

Latest Packt Publishing Java EE 7 books are all around performance and tuning. I had the pleasure to review another book, the  "Java EE 7 Performance Tuning and Optimization" by Osama Oransa.

Abstract
With the expansion of online enterprise services, the performance of an enterprise application has become a critical issue. Even the smallest change to service availability can severely impact customer satisfaction, which can cause the enterprise to incur huge losses. Performance tuning (more...)

Lies, damned lies and non production-like performance testing

Chasing cost efficiency, business often cuts back on money spent on UAT boxes used for performance testing. More often than not, this is a bad-decision, because the only thing worse than not having a UAT environment is having a UAT environment that is nothing like production. It gives a false sense of security while exposing your application to all sorts of nasty surprises. In this post I tried to summarize a few typical configuration differences (more...)

SystemTap into Oracle for Fun and Profit

Topic: This post is about using SystemTap for investigating and troubleshooting Oracle RDBMS. In particular you will learn how to probe Oracle processes and their userspace functions. These techniques aim to be useful as well as fun to learn for those keen into peeking under the hood of the technology and improve their effectiveness in troubleshooting and performance investigations.


Introduction


Userspace probing is a very powerful technique that can be used to complement the available (more...)

JDeveloper 12c ADF View Token Performance Improvement

There is known limitation in ADF 11g, related to accessing application in the same session from multiple browser tabs. While working with multiple browser tabs, eventually user is going to consume all view tokens, he will get timeout error once he returns back to the previous browser tab. Unused browser tab is producing timeout, because ADF 11g is sharing the same cache of view tokens for all browser tabs in the same session. This means (more...)

BPEL 11g threads in parallel flow

A lot has been written about the transactions, boundaries, threads etc in the Oracle SOA Suite. Clemens has written this piece years ago which explains the basics.I recently had a ‘disagreement’ with the SOA threadpool when I was using a parallel flow in a synchronous BPEL process.

The requirement was to guard the execution time of this BPEL process to a predefined maximum amount of seconds. The environment is as such that tweaking the (more...)

12c HCC Row-Level Locking

In Oracle Database 12c we can find many new and shiny things… So many that we can miss the little good things really easy. I think that this one, is one of them. Previously I made a post “All About HCC“, describing how HCC is working and some of the issues that we can hit […]

Querying trace files

SQL trace file provide the highest level of detail possible about SQL execution. The problem with that information is converting it to a convenient format for further analysis. One very good solution is parsetrc tool by Kyle Hailey written in Perl. It gives high-resolution histograms, I/O transfer rates as a function of time, and other very useful info. Unfortunately, I myself am not a Perl expert, so it’s a bit difficult for me to customize (more...)

Oracle IO wait events: db file sequential read

(the details are investigated and specific to Oracle’s database implementation on Linux x86_64)

Exadata IO: This event is not used with Exadata storage, ‘cell single block physical read’ is used instead.
Parameters:
p1: file#
p2: block#
p3: blocks

Despite p3 listing the number of blocks, I haven’t seen a db file sequential read event that read more than one block ever. Of course this could change in a newer release.

Implementation:
One of the important things (more...)

Oracle Cloud Friendly – Red Samurai ADF Performance Audit

I have deployed our tool for ADF performance monitoring to Oracle Java Cloud service. It runs perfectly on the cloud, monitors slow performance and allows to analyse collected performance data. All data is stored in Oracle Database Cloud.

You can access performance monitoring dashboard using this address. Access will be available for a month or so, until my trial account will expire. You would need to use following login credentials - user: redsam, password (more...)

Complément : Analyse des performances sur du long terme

Scaling up Cardinality Estimates in 12.1.0.2

Topic: Counting the number of distinct values (NDV) for a table column has important applications in the database domain, ranging from query optimization to optimizing reports for large data warehouses. However the legacy SQL method of using SELECT COUNT (DISTINCT <COL>) can be very slow. This is a well known problem and Oracle 12.1.0.2 provides a new function APPROX_COUNT_DISTINCT implemented with a new-generation algorithm to address this issue by providing (more...)

Being Right and Proving It

One of the great things about working in IT is that you can often win an argument simply by being right. Not because of who you are or because you are more eloquent than others, but because the facts support your position. Almost every IT person I have ever met respects facts.

In order to win arguments this way, you of course need some facts to work with. And that’s where too many people fail. (more...)

That’s … Huge!

Recently I’ve noticed the occasional thread in Oracle newsgroups and lists asking about hugepages support in Linux, including ‘best practices’ for hugepages configuration. This information is out on that ‘world-wide web’ in various places; I’d rather put a lot of that information in this article to provide an easier way to get to it. I’ll cover what hugepages are, what they do, what they can’t do and how best to allocate them for your particular (more...)

Exadata storage indexes and DML

Last week I’ve gotten a question on how storage indexes (SI) behave when the table for which the SI is holding data is changed. Based on logical reasoning, it can be two things: the SI is invalidated because the data it’s holding is changed, or the SI is updated to reflect the change. Think about this for yourself, and pick a choice. I would love to hear if you did choose the correct one.

First (more...)

New Version Of XPLAN_ASH Utility

A new version 4.1 of the XPLAN_ASH utility is available for download.

As usual the latest version can be downloaded here.

This version in particular supports now the new 12c "Adaptive" plan feature - previous versions don't cope very well with those if you don't add the "ADAPTIVE" formatting option manually.

Here are the notes from the change log:

- GV$SQL_MONITOR and GV$SQL_PLAN_MONITOR can now be customized in the
settings as table names in (more...)