Snowflake Inc.
Multi-Level Metadata in Database Systems

Abstract:

Systems, methods, and devices for multiple level metadata organization in database systems. A system includes a plurality of shared storage devices collectively storing database data across a plurality of tables that each comprise one or more micro-partitions constituting immutable storage devices. The system includes a resource manager configured to manage the storage of database data stored in a table across one or more of the plurality of shared storage devices. The resource manager is configured to manage the storage of metadata for the table. The metadata includes a column expression property with information about data stored in a column, a micro-partition expression property with information about data stored in a micro-partition, a grouping expression property with information about data stored in two or more micro-partitions, and cumulative table metadata with global information about all micro-partitions of the table.