Physical Schema Design - Projections

A projection defines how the records specified by logical tables are actually stored and distributed across the cluster nodes. The following parameters of a physical data representation can be configured using a projection:

• Columns to be included and column encoding (run-length encoding, delta encoding, and so on)

• Column ordering

• Segmentation: The rows to keep on the same node and the projections to be replicated instead of split

  Having multiple projections for the same table impedes data updates. Retain only the necessary projections in your production design.

If a superprojection is not defined for the table, it is created automatically when the first row is inserted into the table. 

Select from the following topics to get more information:

• Columns Encoding and Compression
• Columns Sort Order
• Segmentation
• Configuring the Initial Superprojection with CREATE TABLE Command
• Creating a New Projection with CREATE PROJECTION Command
• Changing Physical Schema