It is generally well known that indices help a lot to speed up database queries (especially SELECT but also UPDATE and DELETE). It is less known, that indices also have some disadvantages.
One of these disadvantages is, that indices require space in memory and on disk. An other disadvantage of indices is, that they slow down DML statements like INSERT and DELETE.

We often see at our customers that they do not realized this behaviour. Now I found the time to show the impact of (too) many indices graphically.

In the following test scenario we created a simple table:

Controlling developers is like herding cats.
Kevin Loney, Oracle DBA Handbook

Oh no, it's not. It's much harder than that!
Bruce Pihlamae, long-term Oracle DBA

Do not assume!
Unknown IT specialist

Backups ist was für Warmduscher!
(engl. Backup is for sissies!)
Unkown DBA

Yesterday (the DBA version)

This MySQL Performance Tuning Key should give you a guide how to best tune you MySQL or MariaDB database systematically... It should also work similar for other RDBMS.

Also check our MySQL Performance Monitor

For a database configuration tuning only please look first at our MySQL/MariaDB database health check.

Release v0.27

• On this page you can check the health of your MySQL/MariaDB database.
• If you want to find out how the MySQL Health Check works try out the examples.
• If you are logged in, our CMS remembers your entry for your next visit.
• If we should send you some advices about the findings please fill in the following form:

mysql> SHOW /*!50000 GLOBAL */ STATUS;

mysql> SHOW GLOBAL VARIABLES;

shell> grep -c processor /proc/cpuinfo

shell> free -m | grep Mem | awk '{ print $2 }'

shell> uname -m