You could say: what could be the reason for having really big number of tables? Just design the application properly! It’s not always that easy. And this post isn’t really about arguing whether having many tables is good or not, it’s about what happens in terms of memory usage if you already reached that point.
Btw what do I mean by *many*? From my experience it’s tens of thousends or even millions rather than hundreds.
The inspiration for me to write this post was strong desire to try out the latest declared improvements in that area announced to be done in MySQL 5.6. _1
What I did was a very simple test where I loaded sql dump of databases and tables definitions only into different versions of MySQL. During the load time I was monitoring memory usage of mysqld process (RSS …[Read more]