Administrating the MySQL Server - Mastering phpMyAdmin 3.4 for Effective MySQL Management - page 331

We also see an Enable Statistics link. By default, statistics are not enabled because
computing the size of data and indexes for all the tables in all the databases may
consume valuable MySQL server resources.
Enabling statistics
If we click on the Enable Statistics link, a modified page appears. For each database,
we get the default collation for tables in this database, along with the number of
tables in the database and the total number of rows for all tables. Next, information
about the space used by the data portion of the tables is given, followed by the space
taken by all indexes, and total space for all tables. Next, the space that could be
reclaimed by optimizing some tables in this database is presented under Overhead
column header. Finally, we can see replication information, followed by Check
Privileges links:
Sorting the statistics
By default, the statistics list is sorted by database name in ascending order. If we
need to find the database with the most tables or the database that takes the most
space, a simple click on the Tables or Total column header sorts the list accordingly.
A second click reverses the sort order.