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By default, for every client connection the MySQL server spawns a separate thread which will process all statements for this connection. This is the ‘one-thread-per-connection’ model. 
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One of the common tasks requested by our support customers is to optimize slow queries.
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In this tutorial, you will learn how to use MySQL SIGNAL and RESIGNAL statements to raise error conditions inside stored procedures.
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This tutorial shows you how to use LOAD DATA INFILE statement to import CSV file into MySQL table.
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Connection strings for MySQL. Connect using MySqlConnection, MySQLDriverCS, SevenObjects MySqlClient, Devarts MySqlConnection, MySQLProv.
Mickael Ruau's insight:
.NET libraries OLE DB providers Wrappers and others
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Every so often people ask me the question how should they estimate memory consumption by MySQL Server in given configuration. What is the formula they could use. The reasons to worry about memory usage are quite understandable. If you configure MySQL Server so it uses too small amount of memory it will likey perform suboptimally. …
Mickael Ruau's insight:
Each thread connecting to MySQL server will needs its own buffers. About 256K is allocated at once even if thread is idle – they are used by default thread stack, net buffer etc. If transaction is started some more space can add up. Running small queries might only barely increase memory consumption for given thread, however if table will perform complex operations such as full table scans, sorts, or need temporary tables as much as read_buffer_size, sort_buffer_size, read_rnd_buffer_size, tmp_table_size of memory might be allocated.
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In this post I will be looking at PHP Sessions, why you need them, how you should store them and I’ll give you a complete class for handling Sessions within a database.
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Can Elasticsearch be used as a "NoSQL"-database? NoSQL means different things in different contexts, and interestingly it's not really about SQL. We will start out with a "Maybe!", and look into the various properties of Elasticsearch as well as those it has sacrificed, in order to become one of the most flexible, scalable and performant search and analytics engines yet.
Mickael Ruau's insight:
via
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Contrairement à la requête insert, la requête delete a une clause where qui peut utiliser toutes les méthodes décrites dans le Chapitre 2, « La clause Where » pour bénéficier directement des index. En fait, la requête delete fonctionne comme une requête selectsuivie d’une étape supplémentaire de suppression des lignes identifiées.
Mickael Ruau's insight:
La suppression réelle d’une ligne suit un traitement similaire à l’insertion d’une ligne, tout spécialement la suppression des références enregistrées dans les index et la conservation de la propriété balancée des index.
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The latest incarnation of this talk as presented on Jan, 31st at FOSDEM PgDay in Brussles
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In his November 24 article Database Thaw Martin Fowler wrote about the lock-in of relational/SQL databases and some possible alternatives. I was with him until he wrote that “you can’t get [a] bigger breach of encapsulation than that,” referring to a central database shared by multiple applications.
Mickael Ruau's insight:
It isn’t the database engine, or the concept of relational databases, or SQL that is the breach of encapsulation. It’s that far too many programmers are either unaware of how to use a database to promote encapsulation, or they don’t see the problem. My own experience is that a lot of programmers learned relational databases from MySQL, which until recently didn’t support things like transactions, stored procedures, views, and triggers, which are required to make a database into something more than a convenient backing store.
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You need to make all new code as independent of the legacy system as possible, just in case the legacy system is replaced. Even if you don’t care about planning that far ahead, you probably don’t want to just tack your new code onto the legacy system.
Mickael Ruau's insight:
The best approach is to write a software layer to isolate the legacy system, a library of functions that can get data in and out and invoke business logic in the old system.
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I've blogged before about how complicated setting up SSL with MySQL can be. Since then many bugs have been fixed related to SSL.
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We just published results with improvements in Thread Pool in Percona Server: Percona Server: Thread Pool Improvements for Transactional Workloads Percona Server: Improve Scalability with Thread Pool What I am happy to see is that Percona Server...
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In this tutorial, you will learn various techniques of how to export MySQL table to CSV file.
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This tutorial shows you how to use MySQL handler to handle exceptions or errors encountered in stored procedures.
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MySQL, like a lot of other software, has many knobs you can tweak. Most of these knobs may affect behaviour, but more importantly most affect the memory usage of the server, so getting these settings right is very important.
Mickael Ruau's insight:
Most of MySQL’s memory is really used just as a cache, in one form or another, information that otherwise is on disk. So ensuring you have as large a cache as possible is important. However, making these memory sizes too large will trigger the server to start swapping and possibly can cause it to crash or cause the kernel to kill the process when it runs out of memory. So that’s something we want to avoid.
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The following list indicates some of the ways that the mysqld server uses memory.
Mickael Ruau's insight:
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Si vous avez besoin de plus de connexion que par défaut (100), vous devez redémarrer mysqld avec une plus grande valeur pour la variable max_connections.
Mickael Ruau's insight:
Le nombre maximal de connexion MySQL dépend de la qualité de la bibliothèque des threads sur une plate-forme donnée. Linux et Solaris devraient être capables de supporter jusqu'à 500-1000 connexion simultanées, cela dépend évidemment de la quantité de RAM que vous avez et de ce que font les clients.
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Par Florent Beranger - Directeur de projet Décisionnel
Mickael Ruau's insight:
Qu'est-ce que le Big Data ? Quels sont les cas d'usages couverts par les solutions de valorisation et d’analyse massive de données ? Quelles sont les meilleures solutions open source dans ce domaine ? Avec ce nouveau livre blanc, Smile vous donne toutes les clés pour décrypter le concept du Big Data et découvrir les solutions qui permettent d'optimiser les processus d'analyse et de prise de décision : Hadoop, ETL Talend for Big Data, ETL Pentaho Data Integration, MongoDB, Elastic Search...
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It is one of the most common questions about indexing: is it better to have one index for each column or a single index for all columns of a where clause?
Mickael Ruau's insight:
The answer is very simple in most cases: one index with multiple columns is better—that is, a concatenated or compound index.
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My most recent experience with an ORM layer was on a free lance project which used Subsonic. To add just one query against existing tables I had to add two new files to the project and change four others. Why? Why do women inflict on themselves the torture of wearing pantyhose and high heels? Why do software developers inflict on themselves the torture of an ORM layers? The answer: Lipstick. No, wait, wrong joke. (And who will understand a couple years from now?). The answer: Fashion. And crowd behavior.
Mickael Ruau's insight:
So, at work Monday I'm expecting we'll be discussing the ORM question and so this weekend I've been doing research. Nah, that's not true. "Research" would imply that my mind is open. I'm not doing research; I'm stockpiling ammunition. Below are some snippets from web pages that I'll be using to support my point of view. If you are interested in this topic, I encourage you to follow the links to the original sources and read the entire articles, especially if you DISAGREE with them, so that you can follow how the author has developed his argument rather than base your reaction on my taken-out-of-context snippets.
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SQL indexing and tuning tutorial for developers covering Oracle, SQL Server, MySQL and others.
Mickael Ruau's insight:
Use The Index, Luke est un tutoriel libre et est fourni sous la licence Creative Commons. La lecture en ligne est possible sur tout périphérique doté d'un navigateur web. Vous pouvez aussi acheter l'édition imprimée ou PDF.
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Most serious software applications store and retrieve data from databases. Relational databases are widely used to reliably manage large amounts of related data. Here are some database design and programming techniques that work well with Abject-Oriented Programming.
Mickael Ruau's insight:
Relational databases are pervasive. Understanding the concepts and learning to use SQL is a requirement for many programming jobs. Although some of the ideas are old and SQL is not as powerful as modern languages such as PHP or Visual Basic, a working knowledge of databases should be part of every professional programmer’s toolbox.
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I've registered for the MySQL 5.6 beta exams, just like many more on Planet MySQL have done.
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