How to configure Jenkins to detect SVN changes and execute a job?

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http://stackoverflow.com – I have configured Jenkins and created a job to checkout, build and run a simple project from SVN. I could configure this job to run periodically, like once every five minutes. But I'd like it to build the project only when something has changed on the SVN repository. I read the "Builds by source changes" section of this document, but could not figure out what exactly I am meant to do! Any help would be appreciated! (HowTos)