fix: PK/FK constraints with an expression (e.g. RELY) dropped and re-added on every incremental run - #1552
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Integration results for PR #1552 — UC cluster ✅ success · SQL warehouse ✅ success · All-purpose cluster ✅ success · Shard coverage ✅ success |
jprakash-db
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Jun 22, 2026
…LY expression A primary/foreign key declared with an `expression` such as RELY was dropped (DROP CONSTRAINT ... CASCADE) and re-added on every incremental run: RELY/NORELY is not exposed by information_schema, so the catalog-read constraint never matched the model's. The CASCADE silently dropped dependent foreign keys and could fail with INTERNAL_ERROR on newer Unity Catalog. Constraint reconciliation now compares PK/FK on (name, columns), ignoring the un-round-trippable expression (and the expression-form FK's to/to_columns) while still detecting genuine FK target changes. Closes databricks#1513
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Description
Resolves #1513.
A contract-enforced incremental PK/FK declaring an
expressionwas dropped and re-added on every run. The catalog read-back (information_schema) never carries theexpression— noRELY/NORELY, and expression-form FKs come back asto/to_columns— so it never matched the model, andget_diffflagged the constraint as both add and drop every run (for anyexpression, not justRELY). The PK drop isDROP CONSTRAINT ... CASCADE, which silently drops dependent FKs and canINTERNAL_ERRORon newer UC.Fix
Compare PK/FK on
(type, name, columns)(dropping the un-round-trippableexpression, andto/to_columnsfor FKs), but emit the original constraints so an ADD keeps itsRELY. Explicit FK target changes (to/to_columns) are still reconciled.Behavior change (accepted regression)
Changing the
expressionon an existing PK/FK —RELY↔NORELY, or an expression-form FK's target — is no longer applied on incremental runs; use--full-refresh. It only worked before as a side effect of the every-run recreate, and the catalog can't report the current state without fragileSHOW CREATE TABLEparsing. PK/FK are informational (NOT_ENFORCED), so this is metadata-only.Tests
TestConstraintsConfig): RELY PK no-op, expression-form FK no-op, explicit FK repoint reconciled, new RELY PK keeps its expression.TestIncrementalRelyConstraintReconciliation): a dependent FK survives an incremental re-run of a RELY-PK parent (asserted viainformation_schema); fails onmain, passes here.Checklist
CHANGELOG.mdupdated.