Backfill constructor

Backfill(TableSchema table, { required Map<String, String> set, String where = 'TRUE', required String doneWhen, int batchSize = 1000, })

Prepares bounded updates over an immutable, non-null historical primary key.

Assignments must be nonempty, target writable non-key columns, and use trusted SQL. batchSize must be positive; doneWhen must be a SELECT probe.

Implementation

Backfill(
  this.table, {
  required Map<String, String> set,
  this.where = 'TRUE',
  required this.doneWhen,
  this.batchSize = 1000,
}) : set = Map.unmodifiable(set) {
  SchemaSnapshot([table]);
  if (batchSize < 1 ||
      set.isEmpty ||
      where.trim().isEmpty ||
      set.entries.any(
        (e) =>
            e.value.trim().isEmpty ||
            !table.columns.any(
              (c) => c.name == e.key && !c.generated && c.computed == null,
            ) ||
            table.primaryKey.contains(e.key),
      )) {
    throw ArgumentError(
      'Backfill needs a positive batch size and assignments to existing non-key columns.',
    );
  }
  if (table.primaryKey.isEmpty ||
      table.columns
          .where((c) => table.primaryKey.contains(c.name))
          .any((c) => c.nullable || c.codec.sqlType == 'json')) {
    throw const OrmException(
      'MIGRATION.BACKFILL_KEY',
      'Backfill requires a non-null primary key with lossless cursor storage; JSON keys are unsupported.',
    );
  }
  if (sqlWords(doneWhen).firstOrNull != 'SELECT') {
    throw const OrmException(
      'MIGRATION.PROBE',
      'Backfill completion must be a SELECT returning one boolean.',
    );
  }
}