Big Metadata: When Metadata is Big Data

The rapid emergence of cloud data warehouses like Google Big-Query has redefined the landscape of data analytics. With the growth of data volumes, such systems need to scale to hundreds of EiB of data in the near future. This growth is accompanied by an increase in the number of objects stored and the amount of metadata such systems must manage. Traditionally, Big Data systems have tried to reduce the amount of metadata in order to scale the system, often compromising query performance. In Google BigQuery, we built a metadata management system that demonstrates that massive scale can be achieved without such tradeoffs. We recognized the benefits that fine grained metadata provides for query processing and we built a metadata system to manage it effectively. We use the same distributed query processing and data management techniques that we use for managing data to handle Big metadata. Today, BigQuery uses these techniques to support queries over billions of objects and their metadata.