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Fixed #27845 -- Allowed both right and left optimizations of operations. 

Thanks Raphael Gaschignard for the suggestion.
This commit is contained in:
Simon Charette 2017-02-18 00:55:13 -05:00 committed by Tim Graham
parent 0025dd5eb4
commit 37cafbfb79
2 changed files with 17 additions and 17 deletions
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24
django/db/migrations/optimizer.py
View File

@ -42,21 +42,29 @@ class MigrationOptimizer:
"""Inner optimization loop.""" """Inner optimization loop."""
new_operations = [] new_operations = []
for i, operation in enumerate(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 # Compare it to each operation after it
for j, other in enumerate(operations[i + 1:]): for j, other in enumerate(operations[i + 1:]):
in_between = operations[i + 1:i + j + 1] in_between = operations[i + 1:i + j + 1]
result = operation.reduce(other, in_between, app_label) result = operation.reduce(other, in_between, app_label)
if isinstance(result, list): if isinstance(result, list):
# Add operations optimized through, optimized operations, if right:
# and the remaining ones. new_operations.extend(in_between)
new_operations.extend(in_between) new_operations.extend(result)
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:]) new_operations.extend(operations[i + j + 2:])
return new_operations return new_operations
if not result: elif not result:
# We can't optimize across `other`. # Can't perform a right reduction.
new_operations.append(operation) right = False
break
else: else:
new_operations.append(operation) new_operations.append(operation)
return new_operations return new_operations

10
tests/migrations/test_optimizer.py
View File

@ -270,8 +270,6 @@ class OptimizerTests(SimpleTestCase):
app_label="testapp", app_label="testapp",
) )
# This could be optimized a bit more but it generates a valid set of
# operations.
self.assertOptimizesTo( self.assertOptimizesTo(
[ [
migrations.CreateModel('Book', [('name', models.CharField(max_length=255))]), migrations.CreateModel('Book', [('name', models.CharField(max_length=255))]),
@ -284,18 +282,12 @@ class OptimizerTests(SimpleTestCase):
migrations.DeleteModel('Person'), migrations.DeleteModel('Person'),
], ],
[ [
migrations.CreateModel('Person', [('name', models.CharField(max_length=255))]), migrations.CreateModel('Book', [('name', models.CharField(max_length=255))]),
migrations.CreateModel('Book', [
('name', models.CharField(max_length=255)),
('author', models.ForeignKey('test_app.Person', models.CASCADE)),
]),
migrations.CreateModel('Reviewer', [('name', models.CharField(max_length=255))]), migrations.CreateModel('Reviewer', [('name', models.CharField(max_length=255))]),
migrations.CreateModel('Review', [ migrations.CreateModel('Review', [
('book', models.ForeignKey('test_app.Book', models.CASCADE)), ('book', models.ForeignKey('test_app.Book', models.CASCADE)),
('reviewer', models.ForeignKey('test_app.Reviewer', models.CASCADE)), ('reviewer', models.ForeignKey('test_app.Reviewer', models.CASCADE)),
]), ]),
migrations.RemoveField('book', 'author'),
migrations.DeleteModel('Person'),
], ],
) )