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Wie der MySQL Optimizer schummelt, wenn es um MySQL Cluster geht...

Bei einem Kunden sind wir auf ein nettes Beispiel gestossen, wie der MySQL Optimizer schummelt, wenn er mit dem MySQL Cluster zusammen arbeiten sollte. Dieser Kunde hat Abfragen, welche auf dem Entwicklungssystem nicht sonderlich langsam gelaufen sind. Aber wenn er diese Abfragen auf dem Abnahmetest-System (mit wesentlich mehr Daten) ausführt, benötigen diese viel zu viel Zeit, was für ihn nicht akzeptabel ist, da diese Abfragen mehrmals pro Sekunde abgesetzt werden können.

How the MySQL Optimizer with MySQL Cluster is cheating you...

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At a customer we had a nice example of how the MySQL Optimizer is cheating when used in combination with the MySQL Cluster. The customer had queries running not too slow in the development environment but when he tried them on the acceptance test environment (with more data) the query was running much too long which was unacceptable because this query can occur many times per second.

What has happened?

First of all we had a look at the execution plan of the query generated by the MySQL Optimizer:

We need you: MySQL DBA for FromDual Support line

FromDual is looking for professional, enthusiastic and experienced people who:

English

FromDual wird Open Database Alliance (ODBA) Silber Partner

Uster, Schweiz -- 26. April 2010 - FromDual ist eine Dienstleistungspartnerschaft mit der Open Database Alliance (ODBA) eingegangen.

FromDual ist der erste offizielle ODBA Dienstleistungspartner in Europa. Die wachsende Zahl der Downloads und die stetig zunehmende Nutzung von MariaDB, eines verbesserten und erweiterten Abkömmlings der MySQL Datenbank, erfordert zunehmend auch Beratungsdienstleistungen für MariaDB in Europa.

FromDual becomes Open Database Alliance (ODBA) Silver Partner

Uster, Switzerland -- April 26, 2010 -- FromDual has signed the Service Provider Partnership Agreement of the Open Database Alliance (ODBA).

FromDual is the first official ODBA consulting partner in Europe. The growing number of downloads and use of MariaDB, an improved and enhanced derivation of the MySQL database, also requires consultancy services for MariaDB in Europe.

FromDual wird Open Database Alliance (ODBA) Silber Partner

Uster, Schweiz -- 26. April 2010 - FromDual ist eine Dienstleistungspartnerschaft mit der Open Database Alliance (ODBA) eingegangen.

FromDual ist der erste offizielle ODBA Dienstleistungspartner in Europa. Die wachsende Zahl der Downloads und die stetig zunehmende Nutzung von MariaDB, eines verbesserten und erweiterten Abkömmlings der MySQL Datenbank, erfordert zunehmend auch Beratungsdienstleistungen für MariaDB in Europa.

German

FromDual becomes Open Database Alliance (ODBA) Silver Partner

Uster, Switzerland -- April 26, 2010 -- FromDual has signed the Service Provider Partnership Agreement of the Open Database Alliance (ODBA).

FromDual is the first official ODBA consulting partner in Europe. The growing number of downloads and use of MariaDB, an improved and enhanced derivation of the MySQL database, also requires consultancy services for MariaDB in Europe.

English

MySQL, where are you going?

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Our presentation MySQL, where are you going? of March 25 at the OpenExpo in Bern is now available in German and English.

When you have missed it, you can download it now from here...

MySQL, wohin gehst Du?

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Unsere Präsentation MySQL, wohin gehst Du? vom 25. März an der OpenExpo in Bern steht jetzt sowohl auf deutsch als auch auf englisch zur Verfügung.

Falls Sie diese verpasst haben, könne Sie sie hier herunterladen...

MySQL Architectures Overview

Database Architecture & Design

Application logic in the middle tier?

Reduce money spent on software licenses by moving logic to the middle tier. This means moving stored procedures into the application server or web server layer where it is much cheaper to scale out. Reducing or eliminating business logic running in the DB may reduce Database CPU utilisation and hence save support costs for the DB Portability is key! [1]

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Limitations of MySQL

Often asked but informations are spread around: The limitations of MySQL.

If you know any other MySQL limitations, please let us know.

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The handler_read_* status variables

Because I do a lot of Performance Tuning gigs I get often in contact with these status variables. In the beginning I had a problem to understand them and now I have a problem to memorize the relation of the name and the meaning. Therefore I wrote this little summary:

Prepare the example

To show you the effect I have worked out a little example:

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Performance Tuning Key for MySQL

This MySQL Performance Tuning Key should give you a guide how to best tune you MySQL database systematically... It should also work similar for other RDBMS.

Also check our MySQL Performance Monitor

For a database configuration tuning only please look first at our MySQL database health check.

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MySQL Monitoring solutions

Basic solutions (CLI)

Those solutions are run from the command line (CLI):

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Profiling MySQL with oprofile

Why is is data load with LOAD DATA INFILE so much faster?

Probably the answer to this question is already known. But we want to prove it and by the way learn to deal with oprofile.

For the test MySQL 5.0.28 was used and 100k rows were loaded into a table sales which looks as follows:

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MySQL Federated Storage Engine

What is a Federated Table?

A Federated Table is a table which points to a table in an other MySQL database instance (mostly on an other server). It can be seen as a view to this remote database table. Other RDBMS have similar concepts for example database links.

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FromDual consulting tool collection

The following tools we use sometimes for our consulting engagements...

Caution: These tools are NOT for production use! Use with care!

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FromDual - The MySQL consulting company goes operational today!

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Hello everybody,

One month earlier than planned we have the great pleasure to announce you that the company called FromDual goes operational today!

We are excited about this step and it is an new era in our personal evolution to get back in full-contact with customers and solve their real life day-to-day MySQL problems.

So we are happy hearing from you and to help you solving your individual MySQL problems...

Presentations

The following presentations are available:

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Logging users to the MySQL error log

Problem

A customer recently showed up with the following problem:

With your guidelines [ 1 ] I am now able to send the MySQL error log to the syslog and in particular to an external log server.
But I cannot see which user connects to the database in the error log.

How can I achieve this?

Idea

During night when I slept my brain worked independently on this problem and in the morning he had prepared a possible solution for it.

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