Archive for February 2009

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./mysqld_safe --user=mysql --basedir=/usr/local/mysql-5.0.67-linux-x86_64-icc-glibc23
--ledir=/usr/local/mysql-5.0.67-linux-x86_64-icc-glibc23/bin --mysqld=mysqld
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./mysqladmin ext -u root -p -ri60
./mysqladmin ext -u root -p -ri60 | grep tmp

The combination of FLUSH STATUS and SHOW SESSSION STATUS can be used to see what happens while MySQL executes a query. First, run FLUSH STATUS to reset session status variables to zero.

mysql> FLUSH STATUS;

mysql> SELECT COUNT(*) FROM TABLE;

Procedure to add a swap file

You need to use dd command to create swapfile. Next you need to use mkswap command to set up a Linux swap area on a device or in a file.

a) Login as the root user

b) Type following command to create 512MB swap file (1024 * 512MB = 524288 block size):

# dd if=/dev/zero of=/swapfile1 bs=1024 count=524288

c) Set up a Linux swap area:

# mkswap /swapfile1

d) Activate /swapfile1 swap space immediately:

# swapon /swapfile1

e) To activate /swapfile1 after Linux system reboot, add entry to /etc/fstab file. Open this file using text editor such as vi:

# vi /etc/fstab

Append following line:

/swapfile1 swap swap defaults 0 0

So next time Linux comes up after reboot, it enables the new swap file for you automatically.

g) How do I verify swap is activated or not?

Simply use free command:

$ free -m