Projections

Changing Projection Column Encodings

You can now call ALTER TABLE…ALTER COLUMN to add an encoding type to a projection column, or change its current encoding type. Encoding projection columns can help reduce its storage footprint, and enhance performance. Until now, you could not add encoding types to an existing projection; instead, you had to recreate the projection and refresh its data. Doing so for very large projections was liable to incur significant overhead, which could be prohibitively expensive for a running production server.

When you add or change a column's encoding type, it has no immediate effect on existing projection data. Vertica applies the encoding only to newly loaded data, and to existing data on mergeout.