database status: reduce number of rows but size still same

[natanet]

helo

when i check to database status. i can see many tables , number of rows and size of each table.

but when i perform "system cleanup", for example delete "Prune Saved Emails" 
 

tblemails 24309 664244.83 Kb

only number of rows reduced but the size still same.. why?

i check in the daily database backup yes the size decreased.. but in the "database status" seems the size still same.. 

 

 

also if we perform "optimise tables", does that method will reduce the size of database?

[natanet]

update:

after perform "optimise tables", yes the size is reduced a lot..

thanks