| Summary: | Beijing Spectrometer (BESIII) experiment has produced hundreds of billions of events. The traditional event-wise accessing of BESIII Offline Software System is not effective for the selective accessing with low rate during a physics analysis. In this paper, an event-based data management system (EventDB) is introduced, which can effectively alleviate the problems of low efficiency of data processing and low utilization of resources. Firstly, an indexing system based on NoSQL database is designed. By extracting specified attributes of events, the events interested to the physicists are selected and stored into the database, whilst the real data of event is still stored in ROOT files. For those hot events, the real event data can also be cached into EventDB to improve the access performance. The data analysis workflow of HEP experiments is needed to change if the EventDB system is applied. The analysis program queries the corresponding event index from database, then get event data from database if the event is cached, or get data from ROOT files if it is not cached. Finally, the test on more than one hundred billion physics events shows the query speed was greatly improved over traditional file-based data management systems.
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