Hi all,
I'd like to discuss a minor inconsistency in the REST Catalog specification
regarding identifier uniqueness within a namespace.
*Background: Inconsistency in Conflict Descriptions*
The REST spec currently defines six write operations that return a 409
Conflict when an identifier already exists: createTable, registerTable,
renameTable, createView, renameView, and registerView.
However, the descriptions for *what* constitutes a conflict are not
consistent:
- *Enforcing cross-type uniqueness* (table or view):
- renameTable, renameView, registerView say: *"already exists as a
table or view"*
- *Only enforcing within the same type* (table or view only):
- createTable, registerTable, createView say: *"table already exists"*
/ *"view already exists"*
This ambiguity leaves it unclear whether a catalog is allowed to have a
table and a view with the same name in the same namespace.
*Proposed Change*
I believe the intent is that identifiers *must* be unique across all
catalog object types within the same namespace (otherwise the rename
operations become impossible to reason about).
The proposed change makes this explicit in two ways:
1. *New CatalogObjectType schema:* Enumerates the known catalog object
types (table, view) and states the uniqueness invariant: *"Identifiers
MUST be unique across all catalog object types within the same namespace; a
table and a view with the same name in the same namespace are not allowed."*
2. *Consistent 409 descriptions:* All six write operations will now
reference CatalogObjectType and use uniform language: *"The identifier
is already used by an existing catalog object (see CatalogObjectType)"*
This change is purely spec-clarification; it introduces no new behavior for
catalogs that already enforce cross-type uniqueness.
The proposed clarification is available here:
https://github.com/apache/iceberg/pull/15691
<https://www.google.com/url?source=gmail&sa=E&q=https://github.com/stevenzwu/iceberg/tree/rest-spec-clarify-id-conflict-requirement>
Thanks,
Steven
