Github user vvysotskyi commented on the issue: https://github.com/apache/drill/pull/1104 @paul-rogers, as you know, there were some differences between the commits in the older Calcite version (1.4.0-r23) which was used by Drill and commits merged into Apache master. One of such commits was `[CALCITE-1150] Add dynamic record type and dynamic star for schema-on-read table`. In our older Calcite fork `DYNAMIC_STAR` was `*`, but after rebase onto Calcite 1.15, it became `**`. As I understand, `DYNAMIC_STAR` itself means "default column" which will be added to table row type for the case when we have `select *` query and the schema of the underlying table is not known. As for the name of constant, I think current `DYNAMIC_STAR` more suitable, since Calcite also uses a similar name for the same string: `DynamicRecordType.DYNAMIC_STAR_PREFIX`. So current name at least helps to avoid divergence in naming for Drill and Calcite.