Trigger Information Data Flow for the ATLAS EventIndex

The trigger information is an important part of the ATLAS event data. In the EventIndex trigger information is collected for various use cases, including event selection and overlap counting. Decoding the trigger information from the event records, stored as a bit mask, requires additional input from condition database and Monte-Carlo trigger database, as trigger configurations evolve with time. It depends on the run number for the real data and from the simulation settings for Monte-Carlo data. We describe trigger information handling in the EventIndex and the interfaces used to access it.