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Grégory Steulet

MySQL Data High Availability with semi-synchronous replication

By | Hardware & Storage | No Comments

Starting with MySQL 5.5 it is possible to configure semi-synchronous replication. As you probably know, by default, MySQL replication is asynchronous.  Asynchronous replication means that events/transactions applied on one server are not immediately applied on the other one. In the specific context of MySQL such behavior means that the MySQL Master writes transactions/events to the local binary logs, however it has no idea when the slave(s) will get and process them. Of course such configuration can lead, in case of failover, to some transaction loss since there is no guaranty that the transactions have been transmitted on the standby server(s).

 
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Stéphane Haby

SQL Server 2012 ‘Denali’: a new panel of DMVs

By | Database management | One Comment

Dynamic management views (DMVs) return server state information that can be used to monitor the health of a server instance, diagnose problems and tune performance.
Since few months, I test the future new version SQL Server 2012 codename Denali and I was very surprised form the news DMVs from this version.
I will just explain some DMVs very interesting for a DBA.
My article is based on msdn web site reference and you find in the end from each chapter a msdn reference for more details of the DMV.

 
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Stéphane Haby

SQL Server Tuning: Detect SPARSE columns candidate

By | Application integration & Middleware | 6 Comments

dbi services search and test all tools or functions possible to optimize or to win something to propose the best tuning possible in their client.
The property of Spare columns is not the most used in client environment that we have seen.
This article present a script to find the potential columns that can have the sparse property with the usage restrictions to make a space tuning in your database and especially for Data Warehouse (DWH).

The database example that we used, is AdventureWorksDW2008R2.

 
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Oracle Team

LOB : « enq : HW contention » 

By | Hardware & Storage | No Comments

Aprés le post sur « Utilisons les securefile », revenons sur le sujet LOB avec une approche performance, stockage.

 Nous rencontrons parfois des modèles de données étranges, nous aurions envies en tant que DBA de tout reprendre à zéro pour refaire un modele relationnel en 3em forme normal (3NF), plus efficace et mieux conçu dans notre « RDBMS » favori, mais la réalité étant ce qu’elle est nous devons faire avec et au mieux.

De plus Oracle n’est pas qu’une base de données relationnelle :-) on l’oublie trop souvent.

 
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Yann Neuhaus

Oracle space management & recycle bin

By | Database management | One Comment

This post describes some basic Oracle database management issues database administrators might be confronted with. It is about space management and differences observed while monitoring the available space from several point of views (tablespace/datafile) in Grid Control 11g. It also relates and explains an issue (ORA-01652) observed on pre 11.2 Oracle releases (targets) concerning the tablespace/datafile space management and the recycle bin. First of all, a simple example: let’s check the used and available space…

 
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Oracle Team

SQL Developer 3.0 : prêt pour les DBA

By | Technology Survey | No Comments

La nouvelle version d’Oracle SQL Developer (version 3.0.03.45) est prête pour les administrateurs de base de données/DBA (voici une vidéo sur cette version). Elle s’est vue agrémentée d’outils nécessaires aux tâches d’administration. Les tests ci-dessous vous présentent, à travers quelques copies d’écrans, les fonctionnalités de l’outil,  en espérant vous donner l’envie de l’adopter.

 
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