Normalize generated-column expressions during sync({ alter: true }) drift detection #18320

Summary

Model.sync({ alter: true }) compares a formatted model generated-column expression with a formatted expression returned by schema introspection.

Databases can normalize generated-column expressions by adding parentheses, casts, identifier quoting, or whitespace. These formatting-only differences can make equivalent expressions compare as different.

Required changes

Update generated-column drift detection to avoid treating formatting-only expression differences as a schema mismatch.

Use the established SQL-expression formatting API for BaseSqlExpression values where appropriate. Normalize equivalent dialect-specific expression formatting before comparison, or classify an unverified text difference as requiring a migration without reporting it as a definite mismatch.

Preserve the current safety behavior for dialects that cannot inspect generated columns. Preserve the SQLite changeColumn path for actual generated-column changes.

Rationale

A semantically unchanged generated column can currently make sync({ alter: true }) fail on dialects that return generated expressions through introspection. SQLite can also rebuild the table repeatedly for an unchanged expression.

Affected area

• packages/core/src/model.js
• Generated-column expression formatting and schema introspection utilities

Acceptance criteria

• Equivalent generated-column expressions with dialect formatting differences do not cause false drift detection.
• Actual expression or generated-column mode changes remain detected.
• Dialects without generated-column introspection retain the existing migration-required safety behavior.
• SQLite does not rebuild a table solely for formatting-only expression differences.
• Tests cover normalized database expressions such as added parentheses, casts, quoting, or whitespace.

Backlinks

• Pull request: feat(core): add generated column support #18303
• Review comment: feat(core): add generated column support #18303 (comment)
• Requested by: @SippieCup