Optimizing Table in database is just like the doing Disk Defragmentation in your PC.
Optimize Table should be used if you have deleted a large part of a table or if you have made many changes to a table with variable length rows, such as VARCHAR, TEXT, BLOB or VARBINARY columns. Deleted rows are maintained in the linked list and insert operations reuse the old row positions. You can use “Optimize Table” to reclaim unused space and defragment the data file for optimal performance. If a lot of changes have been made to a table, optimizing the table can sometimes significantly improve performance.
Here are the steps to optimize a table using phpMyAdmin:
Step 1: Login to phpMyAdmin
Open phpMyAdmin in web browser and enter the login details. If you access phpMyAdmin through CPanel/Plesk then login to it and open phpMyAdmin.
Step 2: Select the Database
Select the database you want to optimize from the list in the left column, which should take you to the “structure” tab for the database.
Step 3: Select the Tables
Select the tables you wish to optimize by checking the check box in front of each one, or clicking on “Check All” if you want to optimize all of them.
Step 4: Optimize Tables
On the drop down box that says “With selected: ” select “Optimize Table.” This will optimize the table and take you to a new screen.