Archive for MySQL
I’m working on building an ideal server setup that allows for both PHP 4 and PHP 5 on Apache with suPHP (I’ll blog about this later). While testing my PHP 4 build, I got the following error:
Warning: mysql_connect() [function.mysql-connect]: Client does not support authentication protocol requested by server; consider upgrading MySQL client in /var/www/test-php.php on line 3
Couldn’t authenticate with MySQL
The code I used to test this is quite simple:
<?php
if ( false === ( $db = mysql_connect( 'localhost', 'username', 'password' ) ) )
die( "Couldn't authenticate with MySQL" );
if ( false === mysql_select_db( 'database' ) )
die( "Couldn't connect to database" );
echo "Yay!";
?>
After digging around for a bit, I found that mixing PHP 4 with a MySQL version greater than or equal to 4.1 causes this problem. MySQL 4.1 introduced a new password caching scheme that PHP 4 can’t work with.
The solution is to update the database user’s password using the OLD_PASSWORD function of MySQL. For example:
[chris@office ~]$ mysql -u root -p mysql Enter password: Reading table information for completion of table and column names You can turn off this feature to get a quicker startup with -A Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 267 Server version: 5.1.41-3ubuntu12.1 (Ubuntu) Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> update user set Password=OLD_PASSWORD('password') WHERE User='username'; Query OK, 0 rows affected (0.02 sec) Rows matched: 0 Changed: 0 Warnings: 0 mysql> flush privileges; Query OK, 0 rows affected (0.00 sec) mysql>
Note the underlined areas. That is where you’ll want to provide your own username and password.
Once you’ve followed these steps, both PHP 4 and PHP 5 will be able to communite with the database.
Thanks to digitalpeer for providing the answer to my issue.
I recently had a issue getting MySQL to read a specific database. Each time I tried to manually query a table in the database, I received the following error message:
ERROR 1018 (HY000): Can't read dir of './default/' (errno: 13)
I’ve seen this message before as it means that there is a permissions issue. I checked the ownerships and permissions, and everything seemed to be in order.
The only thing special about this database is that I have it symlinked to another partition. This has always worked in the past, so I was stumped.
The problem turned out to be that Ubuntu has AppArmor. This software sets up rules that prevent software from gaining access to different areas of the file system. In my case, AppArmor was preventing read and write access to the actual location of my database files.
The solution was quite easy: First, I added the path that I wanted MySQL to have access to in the AppArmor configuration file for MySQL. Second, I restarted the apparmor service. Here’s the technical details:
- On my system, the configuration file that controls MySQL permissions through AppArmor are located at /etc/apparmor.d/usr.sbin.mysqld. The following shows the contents of the file as it now exists:
# vim:syntax=apparmor # Last Modified: Tue Jun 19 17:37:30 2007 #include /usr/sbin/mysqld { #include #include #include #include #include capability dac_override, capability sys_resource, capability setgid, capability setuid, network tcp, /etc/hosts.allow r, /etc/hosts.deny r, /etc/mysql/*.pem r, /etc/mysql/conf.d/ r, /etc/mysql/conf.d/* r, /etc/mysql/my.cnf r, /usr/sbin/mysqld mr, /usr/share/mysql/** r, /var/log/mysql.log rw, /var/log/mysql.err rw, /var/lib/mysql/ r, /var/lib/mysql/** rwk, /var/log/mysql/ r, /var/log/mysql/* rw, /var/run/mysqld/mysqld.pid w, /var/run/mysqld/mysqld.sock w, /home/sites/default/mysql/ rw, /home/sites/default/mysql/* rw, /sys/devices/system/cpu/ r, }The two lines in bold show what I added to the configuation. The first line gives read and write access to the directory itself while the second gives read and write access to the files contained in the directory.
- After saving the configuration changes, I simply needed to restart the AppArmor daemon. I did this with the following command:
[chris@rommie ~]$ sudo service apparmor restart * Reloading AppArmor profiles Skipping profile in /etc/apparmor.d/disable: usr.bin.firefox
I recently worked on a project where I had to sort a set of rows returned from a MySQL query. The problem is that most of the data in the field being sorted is numeric yet the field type is varchar since some of the entries contained characters.
The reason that this is a problem is that MySQL sorts character fields using a method that will produce undesirable results with numeric data. For example, sorting 4, 10, and 50 as character data produces 10, 4, and 50. In most applications, this is highly undesirable.
The solution to this is to force a sorting order that is commonly referred to as a natural sort. Natural sort is just a term that refers to how humans would commonly sort a set of information (numbers as numbers and non-numeric characters alphabetically). Fortunately, this isn’t difficult to achieve in MySQL.
Continue reading “MySQL Natural Sort Order By on Non-Numeric Field Type”
Web applications developers such as myself often have a hard time keeping up with everything that’s going on. There’s always some new programming or scripting language, new standards, new browsers, new technologies, new paradigms, new social networks, and on and on. Every day, something new happens. The end result of all of this always ends up being very similar: people demand faster applications that deal with ever-increasing amounts of data which end up putting massive stress on the server architecture.
As we toil to improve the performance of the applications and their snappy response times, it becomes easy to forget about how we can tweak settings on a low level to provide massive speed improvements on the front-end. For example, most people don’t know that you can configure MySQL to take better advantage of the resources that the server has available.
By default, MySQL is configured to consume a relatively limited amount of memory resources. Start giving MySQL more memory to work with, and your application’s performance can improve greatly.
Continue reading “Tool to Optimize MySQL Configuration and Performance”