I have written before about using joins instead of subqueries, especially for NOT IN queries, which can usually be rewritten as exclusion joins – sometimes with huge efficiency gains. In this article I’ll look more closely at the performance characteristics of a few queries I’ve optimized in MySQL 5.0.3. I’ll also show you some tricks you can use to get MySQL to optimize queries better when you know it’s being inefficient.

There could be many reasons why a connection to MySQL server can fail, like

• Networking Problem
• Server itself could be down
• Authentication Problems
• Maximum Connection Errors allowed.

Of all the errors, this thread will discuss Maximum Connection Errors.
This particular parameter max_connect_errors defines the no. of connection errors a particular host can make before it is banned. Yes Banned! This is a feature that MySQL provides to limit erroneous clients.

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There could be many reasons why a connection to MySQL server can fail, like

• Networking Problem
• Server itself could be down
• Authentication Problems
• Maximum Connection Errors allowed.

Of all the errors, this thread will discuss Maximum Connection Errors.
This particular parameter max_connect_errors defines the no. of connection errors a particular host can make before it is banned. Yes Banned! This is a feature that MySQL provides to limit erroneous clients.

read more

MySQL will allow n number of connections at a given point of time, To find out that n no of connections run the following command.

mysql> show variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 100   |
+-----------------+-------+
1 row in set (0.00 sec)

So this server will allow max of 100 connections at any given point of time.

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MySQL will allow n number of connections at a given point of time, To find out that n no of connections run the following command.

mysql> show variables like 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 100   |
+-----------------+-------+
1 row in set (0.00 sec)

So this server will allow max of 100 connections at any given point of time.

read more

Tomorrow morning at 7:30 AM I will be leaving from Monterey for San Francisco where we (me and Michelle) will be catching a flight to Atlanta at noon. We will arrive in Atlanta around 8:00 PM EST. I believe we will have the shortest day ever due to the time difference.

I am really thankful to MySQL and especially Arjen and Jay for inviting me to speak at the MySQL Users Conference. I enjoyed it a lot and will miss everyone I met until we meet again. Thank you everyone for such a great time.

Frank

MySQLUC

or, why I find the Solaris manual pages amusing.

In this thread on the php internals list, Kevin is asking why the handling of whitespace in certain PDO DSNs is inconsistent. I go on to point out that the manual doesn't say anything about whitespace in DSNs, and that all the documented examples have no whitespace around the DSN parameters.

His response was:

   but in this example we have a space and it works
   mysql: host = localhost; dbname=test

And another that I got via private email:

Read more...

Thursday’s Keynote speaker at the MySQL Conference was Mark Shuttleworth talking on The Ubuntu Project: Improving Collaboration in the Free Software World.

Ubuntu from Canonical Ltd is fastly becoming one of the most popular Linux Distributions, based on Debian. Here were some notes from his presentation. Mark had some really powerful one or two line slides that typified both his presentation intention and the goal of Ubuntu.

Delivering on the Promise of Free Software

• MySQL levelled the playing field, individuals could use MySQL to build applications that could now compete in the …

It's hard to believe that MySQL Users Conference is over. Though each day seemed like very long, it went pretty fast.

My Applied Ruby on Rails and AJAX session was the last session at the MySQL Users Conference and was happening at the same time as Jim Starkey's Falcon storage engine. I was kinda worried about the attendance at first, but when my session started, I saw people standing in the back (full room). A lot of questions were asked at the end. Thanks to everyone who attended.


Harrison Fisk, my session buddy, presented me with a speaker's gift from MySQL, which was a very nice MySQL pen (Thanks).

At the end of the session I was told that there were about 114 people attending my session, roughly the same amount of folks that attended Jim's session, Wow!.

As I was walking out of the …

Well, the conference is now over! I had a great time, and met a lot of awesome people. It was awesome, I truly enjoyed meeting many of you, and will definitely see you next year.

I’ve uploaded my photos and presentations for your enjoyment:

• MySQL UC 2006 Gallery
• Replication for Scaling and High Availability (ppt, pdf)
• MySQL …