diff options
Diffstat (limited to 'django')
| -rw-r--r-- | django/db/migrations/optimizer.py | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/django/db/migrations/optimizer.py b/django/db/migrations/optimizer.py index 26ac88a221..7974dba66b 100644 --- a/django/db/migrations/optimizer.py +++ b/django/db/migrations/optimizer.py @@ -42,21 +42,29 @@ class MigrationOptimizer: """Inner optimization loop.""" new_operations = [] for i, operation in enumerate(operations): + right = True # Should we reduce on the right or on the left. # Compare it to each operation after it for j, other in enumerate(operations[i + 1:]): in_between = operations[i + 1:i + j + 1] result = operation.reduce(other, in_between, app_label) if isinstance(result, list): - # Add operations optimized through, optimized operations, - # and the remaining ones. - new_operations.extend(in_between) - new_operations.extend(result) + if right: + new_operations.extend(in_between) + new_operations.extend(result) + elif all(op.reduce(other, [], app_label) is True for op in in_between): + # Perform a left reduction if all of the in-between + # operations can optimize through other. + new_operations.extend(result) + new_operations.extend(in_between) + else: + # Otherwise keep trying. + new_operations.append(operation) + break new_operations.extend(operations[i + j + 2:]) return new_operations - if not result: - # We can't optimize across `other`. - new_operations.append(operation) - break + elif not result: + # Can't perform a right reduction. + right = False else: new_operations.append(operation) return new_operations |