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David Hueber

Oracle Basics (3) – Database startup and shutdown

By | Database management | 6 Comments

It’s already quite a while that I posted my last article on the Oracle basis, so I decided to take some times in the train to continue this small serie.
This time, I’m going to speak about one of the root of Oracle administration, starting and shutting down a database.

Startup and shutdown processes within oracle databases are splitted in different steps (for startup) and modes (for shutdown) and even if these principles are quite trivial, some confusions between these steps and/or modes can easily be done. So I’m going to give a picture of both of these processes and their variations.

Before shutting any database down, it needs first to be started, so let’s begin with the startup process…

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Stéphane Haby

A brief PowerShell 2.0 overview

By | Database management | No Comments

SQL server 2008 has PowerShell and at the end of this article, I speak of this topic but to use correctly Powershell, you must have a basic notion about this technologie.

In microsoft Techdays in Basel, Marc van Orsouw presents Powershell.
I think it was a nice opportunity to presents you an overview of Powershell based on this

presentation with adding microsoft msdn web site commentar.

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Yann Neuhaus

How to retrieve previous table statistics using Oracle dbms_stats

By | Application integration & Middleware | 4 Comments

Sometimes, you need to modify the statistics of a table. There are various reasons: either for the performance analysis or because the execution plan changed. Oracle offers two methods: statistics restore or statistics export. Both are in the dbms_stats package. 1. Statistics restore This method uses the procedure dbms_stats.restore_%_stats, where % can be table, schema, database, and fixed_objects. This is an example for a restoration of a table with definite timestamp. The starting situation is:…

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Pierre Sicot

Pourquoi mettre une base de données Oracle en force logging ?

By | Database management | One Comment

Certaines requêtes DDL offrent la possibilité de ne pas générer des enregistrements dans les redo log via la clause NOLOGGING. Le mode nologging permet donc dans certains cas d’accélérer des traitements, ceux-ci pouvant facilement être récupérables à travers des mécanismes externes à la base de données. Ce mode peut cependant avoir des conséquences fâcheuses comme nous allons le constater et ce pas uniquement dans le contexte de configurations comme Oracle DataGuard.

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Grégory Steulet

Stop looking for Oracle Fusion and Oracle Grid Control documentation: use the dbi services firefox add-ons!

By | Database management | One Comment

After my last post title “Stop looking for Oracle and MySQL documentation: use the dbi services firefox add-ons!” Some of you asked me for firefox search add-ons for Oracle Fusion Middleware (http://download.oracle.com/docs/cd/E17904_01/index.htm). This add-on will provide you a fast a reliable way to find easily what you are looking for in the official oracle documentation.

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Jérôme Witt

VMware Tools auf Oracle Enterprise Linux 5.6 Guests installieren

By | Hardware & Storage | No Comments

Wenn Sie einen Oracle Datenbank Server auf VMware ESX betreiben, sollten Sie die VMware Tools nicht unterschätzen. Sie sind nicht nur sinnvoll bei Copy-Paste-Aktionen oder für bessere Grafiken, sondern liefern ebenfalls High-Performance-Network, Storage Adapter (PVSCI), Treiber, etc. Auf Linux Guests müssen die Tools mit dem Kernel zusammen kompiliert werden. Besonders auf Oracle Enterprise Linux 5 Upgrade 6 gibt es ein Problem: OEL 5.6 und OEL 6.0 nutzen den neuen Oracle Unbreakable Kernel 2.6.32-100. Wenn Sie…

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Hervé Schweitzer

A SQL statement is slow and suddenly fast? Have a look at “Cardinality Feedback”!

By | Application integration & Middleware | 2 Comments

Discussing with some tuning gourous we were made aware about this feature. It is not so far from the adaptive cursor sharing perfectly described in  Chris’s blog : http://antognini.ch/papers/BindVariablePeeking_20090718.pdf

This feature, compares the real execution (number of returned/actual rows “A-rows”) with some expectations (number of expected rows “E-rows”) and chooses another plan for the next executions if the difference between the expectation and the actual result is too big. “Cardinality Feedback” is not well documented in the Oracle documentation.

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Grégory Steulet

Saving time and increasing service availability with MySQL Enterprise Monitor 2.3

By | Hardware & Storage | 3 Comments

Nowadays MySQL Databases are encapsulated into many mission critical software solutions. Lots of companies host one or many MySQL databases in their data center, sometimes even without knowing it except when the MySQL service is no more available. In order to increase this service availability it is mandatory to have a monitoring solution. Regardles of you are using MySQL Server, MySQL replication or cluster the Oracle/MySQL monitoring solution is called MySQL Enterprise Monitor.

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Grégory Steulet

Stop looking for Oracle and MySQL documentation: use the dbi services firefox add-ons!

By | Database management | 2 Comments

Are you often trying to find some functionalities into ORACLE 10gR2, ORACLE 11gR2 or MySQL documentation ? Of course each time you are looking for this documentation you find unofficial documentation which is never corresponding to the version you are looking for.. we have the solution, three firefox add-ons that will allow you to easily find the right official Oracle or MySQL documentation you are looking for.

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Grégory Steulet

Simulating and testing I/O performances with ORION

By | Application integration & Middleware | One Comment

Since Oracle 11.2, Oracle provides ORION in the RDBMS binaries (in ${ORACLE_HOME}/bin). ORION is an I/O calibration tool allowing to simulating and testing I/O performances an Oracle database would be confronted with.

 

ORION basically supports four kinds of database activities based on either small or large I/O. ORION can, as any respectable I/O simulation tool, generate an adapted workload using a given percentage of reads and write operations.

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Yann Neuhaus

Simulating database-like I/O activity with Flexible I/O

By | Application integration & Middleware | No Comments

You do not want to install or configure swingbench, load runner etc. – just to test the performance of your I/O system based on filesystems? Then Flexible I/O is the right tool for you. This post provides an overview. In order to simulate Oracle database I/O workload on filesystems, ORION cannot be used since it only uses raw or block devices (scratching the filesystem). To simulate Oracle database I/O behaviour on filesystems, we can use…

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