Working with Projections
Unlike traditional databases that store data in tables, Vertica physically stores table data in projections, which are collections of table columns.
Projections store data in a format that optimizes query execution. Similar to materialized views, they store result sets on disk rather than compute them each time they are used in a query. Vertica automatically refreshes these result sets with updated or new data.
Projections can be generally classified in two ways:
- How projection data is distributed on the cluster. A projection can be defined to divide its data into multiple segments, or maintain all projection data as a single unsegmented unit.
- How much data a projection contains, and the nature of that data. For example, each table Vertica requires a superprojection, which contains all table columns. You can also create query-specific projections, which contain only the subset of table columns to process a given query.
For more general information about Vertica projections, see Physical Schema in Vertica Concepts.