Snowflake Inc.
Storing database metadata in multiple levels

Abstract:

The subject technology stores database data in a table, the table comprising a plurality of micro-partitions each having rows and columns. The subject technology stores metadata for the table in a data structure, the metadata comprising a first level of the data structure comprising a column expression property comprising information about data stored in a column of a micro-partition of the table, a micro-partition expression property comprising information about data stored in the micro-partition of the table, and a second level of the data structure comprising a grouping expression property comprising information about data stored in the micro-partition and one or more additional micro-partitions of the table.