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... 8 Oct 2012 | 02:52 am
Mohammed Amine BENABDALLAH Professeur de droit public, Université Mohammed V, Agdal-Rabat - Doctorat d'Etat en Droit public, Universite de Paris II; - Diplôme des Etudes supérieures en sciences admin...
MySQL Left Join 6 Jul 2011 | 09:23 pm
Even if you think you know everything about LEFT JOIN, I bet you will learn something or two in this post! A reminder about “A LEFT JOIN B ON conditional_expr” The ON condition (in the expression “A L...
As restoring a dump table into the MySQL master – you better get some sleep 4 Apr 2011 | 08:09 pm
Restoring a dump table into the MySQL master server can lead to serious replication delay. The massive inserts commands cause the Master and slaves to use most of their resources for replication. As a...
If you copy a MyISAM table with PRIMARY key, don’t forget to order the rows first 15 Mar 2011 | 06:02 am
In a case that you copy (INSERT INTO .. SELECT ..) a MyISAM table that have a PRIMARY key, it is much faster to insert the new rows in the primary key order: The insertion will be faster: because the ...
You Must Have A Killer In Your System 9 Feb 2011 | 05:10 am
Every system can have a slow query that randomly seems to emerge from nowhere. The main threat from these slow queries is that it can unexpectedly bring down your site. Even though the query is not ca...
A many to many relationship table – solving the exclude relation problem 19 Jan 2011 | 01:36 am
I will start by defining the MySQL Many to Many relationship (Experts can skip to the next paragraph) What is A MySQL many to many relationship A MySQL many to many relationship is a relationship that...
The battle between FORCE INDEX and the QUERY OPTIMIZER 26 Oct 2010 | 09:15 am
Query Optimizer is a part of the server that takes a parsed SQL query and produces a query execution plan. MySQL Query Optimizer uses (as one of its parameters) the stored key distribution (Cardinalit...
Optimizing the MySQL IN() Comparison Operations Which Include the Indexed Field 8 Oct 2010 | 12:06 am
The MySQL IN() Comparison Operator is said to be very quick if all the values are constants (the values are then evaluated and sorted first, and the search is done using a binary search). However, wha...
MySQL User Defined Variables 3 Jun 2010 | 09:04 am
When I have discovered MySQL User-defined variables at the first time, I didn’t pay much attention to them and didn’t realize their strength. At first, one can think that they are just one of the many...
Limited SELECT count(*) 14 May 2010 | 09:52 am
A SELECT statement with COUNT returns the number of rows retrieved by the SELECT statement (see mysql select count). For performance reasons, the desired result is to limit that count. Including a LIM...
