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ClickHouse® is an open-source, high performance columnar OLAP database management system for real-time analytics using SQL.

We internally use it to store information like:

  • event
  • person
  • person distinct id / session

and to power all our analytics queries.


  • sharding: is a method for horizontally partitioning a dataset
  • shard: holds a partition of the dataset
  • replica: is a node part of a shard
  • distributed table: is a table distributed across multiple shards