Querying of materialized views for time-series database analytics

摘要

Materialized views are maintained for time-series databases, to enable faster analytics over large data sets and to downsample data for storage savings. These materialized views are the result of computations on existing tables, such as aggregation, approximation, sampling, filtering, statistical estimates, and more. A materialized view is created on a base table, and continuously maintained, such that as changes are made to the base table, the materialized view is correspondingly updated, either synchronously or asynchronously. The database system records metadata identifying regions of the base table that have already been materialized. Subsequently, these invalidated regions are rematerialized. Queries ensure up-to-date results by combining data from the materialized view with results calculated at query time on the base table. Invalidation records and completion thresholds are used to determine which results should use records from the materialized table and which from records from the base table. Hierarchical materializations are also maintained.