Problem : Sir, More and more spam comments are using much of database memory. I am unable to review all the comments because i don’t have much time to review all these comments. Please suggest me a way to prevent these spam attack and to lower down the database size while managing comments.

Suggestion :

Way 1 : Premium Plugin for Spam Protection (Akismet)

1. Firstly you need to activate plugin called akismet which will prevent spam to great extend so that you would be able to review all the valid comments.
2. Akismet is paid version and still your comments will be stored in your database which will grow your database eventually.
3. In the WordPress all the comments are maintained in the following two tables -

4. As blog grows in terms of visitors many more comments will be stored inside these two tables and your database will grow day by day.

Way 2 : 3rd Party WordPress Comment System

1. Instead of using default commenting system of WordPress we can use 3rd party comment systems such as Disqus [Disqus – The Web’s Community of Communities] It will divide load on your database.
2. All the comments will be stored in the Disqus database and you will divide your load significantly. Only ping backs and trackbacks will be stored inside your default WP commenting system.
3. Disqus will handle all the user entered comments and also provide you spam protection.
4. Important thing about Disqus is that it is available to us free of cost and we can earn some revenue by using Disqus Revenue Program (Optional) .