Geek Answers Handbook

MySQL de-optimization

Is there a simple command that will allow me to configure an instance of MySQL DB to run slower than usual?

I am working on code that records and repeats interacting with databases. One of the things that it does is to keep track of how much time a given request / command needs to complete, and if it runs much slower during a replay, it will issue a warning. Of course, if you do not experience this, it does not work; I am trying to come up with an automated test for this feature. Is there something I can do with my test database that will ruin the performance? All I have to do is securely add 2+ milliseconds to any given request, and I am set up.

+7
source share
2 answers

If you just want to check long queries, do the following: SELECT SLEEP(1);

It doesn’t matter which request itself, if all you want to do is check if your duration detection works.

(I know this violates the true aspect of “replay”, but it should be trivial to add SLEEP(1) during “replay” to some select statements.)

EDIT:

A second idea that might seem better to you is to create a table lock from another connection. Run the script. Wait a bit. Remove this lock. It will not interfere with any of your playback requests.

+9
source

The basic procedure:

  • start a transaction

  • Make your sql stuff

  • 2 ms sleep in perl or sql

  • fixation

the key is part of begin / commit: it will store any locks you acquired, making things as slow as you want.

Other tests to consider:

  • start a transaction in two processes

  • Make your sql stuff in the first process

  • Make your sql stuff in the second process

  • make more sql files in each process

  • complete every process

+1
source

More articles:


All Articles