Referential integrity is not a big problem in analytic databases. Finding things is. ClickHouse uses primary key indexes to locate blocks of rows quickly in ver

Referential integrity is not a big problem in analytic databases. Finding things is. ClickHouse uses primary key indexes to locate blocks of rows quickly in very large tables. The indexes are sparse and by default only have 1 entry for every 8192 rows. The organization allows the index to fit in RAM even when the table is very large. This is a common design choice in analytic systems.