SchemaMigrator

class SchemaMigrator(driver: SqlDriver)

Automatic schema migration — called inside every generated createTable().

Decision logic:

No change → no-op
Only new columns → fast path: ALTER TABLE ADD COLUMN for each
Orphaned columns → slow path: full 12-step table recreation (drops dead columns)
Renamed column → add @Column(migrateFrom="old_name"); triggers slow path, data copied from old column into new one
Type changed → slow path; old data CAST into the new declared type

Removed columns are always cleaned up — they never linger as orphans.

Constructors

constructor(driver: SqlDriver)

fun sync(tableName: String, expectedColumns: List<ColumnDef>)