Hi all, Now that the IRC "labels" field has merged in Iceberg Spec ([0]) and the Polaris Tag work is close ([1]), I'd like to open a thread on how Polaris should support labels.
There are two ways Polaris could do labels: A) Labels as a separate entity - their own definitions/store, parallel to Tags. B) Labels as a projection over Tags - read-only IRC view / projection of the existing tag model. I propose B. Tags already are the structured model: definitions, assignments, allowed values, inheritance, reverse lookup. IRC labels are designed as the flat read surface of such models (object-level key/values plus per-field labels by field-id). A separate labels entity would duplicate the tag model and create two sources of truth to reconcile; a projection keeps one model with two surfaces, a structured authoring API and an interoperable flat read field. Column identity already lines up: Tags use the Iceberg field-id, and IRC labels fields are keyed by field-id. Given B, a Polaris catalog plays two roles: 1. Producer. Polaris resolves a target's effective tags (inheritance applied, closest-wins) and projects them into IRC labels on loadTable/loadView. The Tag API stays the authoring/management surface and labels is the read projection for IRC compliant engines. 2. Consumer. When Polaris federates a foreign IRC catalog, it reads that catalog's labels and stores them as tags owned by the source catalog: read-only in Polaris and clearly marked as foreign. A Polaris user cannot edit them (they change only when Polaris re-syncs from the source) and they stay separate from Polaris's own natively-authored tags. That is how a foreign catalog's metadata becomes usable in Polaris without pretending it is local. Mostly I'd like the community read on whether projection-over-tags feels right, and whether the producer/consumer split is worth keeping in mind in the Tag design so the contract leaves room for it. Would like to hear if this framing is wrong, or where a separate entity would actually serve better. Thanks, Andrei [0] IRC Labels spec PR - https://github.com/apache/iceberg/pull/15750 [1] Tags discussion thread - https://lists.apache.org/thread/28h8bvg3pwwmpob2p4gcrpfs1x5cgkmn
