Surya's Blog!

Month: November 2017

  • How to get the all the database and table sizes of MySQL or MariaDB?

    How to get the all the database and table sizes of MySQL or MariaDB?

    If you are working with MySQL or MariaDB web server, sooner or later you will be asked what is the size of database or tell me the size of all the database and table sizes.

    You can get the a particular databases tables and indexes size using below mentioned SQL query.

    SELECT 
    table_name AS `Table`, 
    round(((data_length + index_length) / 1024 / 1024), 2) `Size in MB` 
FROM information_schema.TABLES 
WHERE table_schema = "$DB_NAME"
    AND table_name = "$TABLE_NAME";

    To get the size of all the databases and tables in MySQL or MariaDB use below query.

    SELECT 
     table_schema as `Database`, 
     table_name AS `Table`, 
     round(((data_length + index_length) / 1024 / 1024), 2) `Size in MB` 
FROM information_schema.TABLES 
ORDER BY (data_length + index_length) DESC;

    This is how you can get all the tables and databases sizes in MySQL. You can later pivot the records to get the cumulative sizes of all the databases in MS Excel or Libreoffice.

  • How to set or change default text editor for crontab in Linux?

    How to set or change default text editor for crontab in Linux?

    To edit the crontab entries you use crontab -e. The command will check for the environment variables $EDITOR or $VISUAL.

    So you need to set the  $EDITOR or $VISUAL variable. Let’s learn how to do that.

    To Set the default editor to (Vim) for crontab editing

    $ export VISUAL=vim

or

$ export EDITOR=vim

Then
$ crontab -e

    To set the default editor to (nano) for crontab editing

    $ export VISUAL=nano

    To set the default editor to (ed) for crontab editing

    $ export VISUAL=ed

    to exit from ed you need to type q and press enter.

    This is how you can set the default editor for crontab in linux.