A validation rule is a basic or integrity rule that you can apply to metadata items to check the validity of your data. It can be basic check for correct values or referential integrity check, both applicable to database tables or individual columns, file metadata or any relevant metadata item.
This feature is not shipped with your Talend Studio by default. You need to install it using the Feature Manager. For more information, see Installing features using the Feature Manager.
All your business and validation rules can now be centralized in Repository metadata which will enable you to modify, activate, deactivate and delete them according to your need.
They can be defined either from the Validation Rules metadata entry or directly from the metadata schema or columns you want to check and they are to be used in your Job designs at the component level. Data that did not pass the validation check can easily be retrieved through a reject link for a further treated, if necessary.
To see how to use a validation rule in a Job design, see Data Integration Job Examples.