Modern BigData technologies to store and access metadata for the ATLAS experiment

Structured data storage technologies evolve very rapidly in the IT world, driven by BigData projects. LHC experiments, and ATLAS in particular, select and use these technologies to store a wealth of metadata, balancing the performance for a given set of use cases with the availability, ease of use and of getting support, and stability of the product. Our community definitely and definitively moved from the "one fits all" (or "all has to fit into one") paradigm to choosing the best solution for each group of data or metadata and for the applications that use these data. This paper describes the solutions in use, or under study, for the ATLAS experiment and their selection process and performance.