Can you change encoding of a column on a projection without recreating the projection?

May_1

Can you change the encoding type of a column on a projection without recreating the projection? Maybe in an ALTER PROJECTION statement?

Daniel_Leybovic

Hi!

Only rename
http://my.vertica.com/docs/7.0.x/HTML/index.htm#Authoring/SQLReferenceManual/Statements/ALTERPROJECT...

Sajan_Sangraula

Your best is to create a new projection with the changed column projection, refresh it using select start_refresh(), and then drop the existing one.

/Sajan

colin_loghin

Changing the projection encoding would require reorganizing the underlying storage for the column. It is true that if sort order / segmentation is not changed then only the specific column file would be affected and hence would be more effective to reorganize just 1 column rather than all columns, but the feature does not seem to exist. The option is rebuilding the projection in its entirety.

Jim_Knicely

This is now possible starting in Vertica 10!

See: Changing Projection Column Encodings