Linux Admin Zone

Here is the situation: We are doing replication of only 1 table from a database (live) to other host (backup). so we expect that updates which are on others DBs/tables except on this table should not replicate. Wrong! they got replicated.

We shifted one DB say DB1 from live env to Backup DB host and then removed that DB1 from Live. Even replication was only for a single table of a particular DB say DB5, DB1 got removed from Backup host as well, living us in vaccum

MySQL stopped default inclusion of InnoDB in latest 5.1.x, so if you need InnoDB, you have to compile it from source. I have done following steps in CentOS 5.4 server to compile MySQL and optimize it later for a heavy site:

1. Remove earlier installation of MySQL, if any and download source rpm from MySQL site. I’ve also removed earlier installation of PHP here to upgrade it:

$ rpm -e php-mysql mysql-server php php-devel php-pear

Download the latest source rpm from MySQL download site, you will get source rpm like below and install it. Installation of source rpm will put it as tar file in /usr/src/redhat/SOURCES, make sure to create /usr/src/redhat/SOURCES directory before installation:

Recently I was in need to convert all databases of a MySQL server from MyISAM engine to InnoDB. They are facing severe issues due to table level locking in MyISAM and wanted move to InnoDB. This task can be a mammoth work but if you work little smarter, all you need to execute few statements and look at the progress while having cup of coffee. Also note that you can convert in both side, means from MyISAM to InnoDB and from InnoDB to MyISAM using these commands.

Sometimes in large deployments, there are cases when MySQL server, setup by you long time back which has been in use by multiple teams in your organization, needs some change or update or intrupption in its service and you are in need to know how many clients are there which connects to this server.

One way to know is to check user table in ‘mysql’ database, you might have created individual users/databases for your clients/users. But over the time, unless taking care seriously, we tend to forget the exactly how many users/scripts/machines are there making connections. May be you have used same read-only user in various scripts scattered over many machines which you’ve created just for a single client.

MySQL Cluster is used to provide high-availability, high-redundancy for the distributed computing environment. You might know that beginning with MySQL 5.1.24, support for the NDBCLUSTER storage engine was removed from the standard MySQL server binaries built by MySQL. Therefore, here I’m using MySQL Cluster edition instead of MySQL Community edition. I’m using 3 servers (1 Management and 2 data) to setup cluster in CentOS 5.4 Linux box. The steps mentioned here can be used for quickly deploying a cluster and worked out for me but no guarantee that this will work for you, So its always advisable to go through official MySQL guide as well for production environment. In case you are also riding on cloud computing wave, I’ve already blogged way to setup MySQL cluster in Amazon EC2 environment.