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Code Issues 32 Releases Wiki Activity

Refs #29808 -- Optimized MigrationExecutor.detect_soft_applied().

Browse Source 
Use set() for iterables used only for containment checks. Simplify
column checks O(n) instead of O(2n).

Thanks Simon Charette for an idea.
This commit is contained in:
Hasan Ramezani
2019-11-14 21:19:18 +01:00
committed by Mariusz Felisiak
parent 24b9f50823
commit d0c86a1df4
1 changed files with 10 additions and 8 deletions
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18
django/db/migrations/executor.py
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@@ -330,7 +330,7 @@ class MigrationExecutor:
found_create_model_migration = False
found_add_field_migration = False
with self.connection.cursor() as cursor:
existing_table_names = self.connection.introspection.table_names(cursor)
existing_table_names = set(self.connection.introspection.table_names(cursor))
# Make sure all create model and add field operations are done
for operation in migration.operations:
if isinstance(operation, migrations.CreateModel):
@@ -363,14 +363,16 @@ class MigrationExecutor:
else:
found_add_field_migration = True
continue
column_names = [
column.name for column in
self.connection.introspection.get_table_description(self.connection.cursor(), table)
]
if field.column not in column_names:
columns = self.connection.introspection.get_table_description(
self.connection.cursor(),
table,
)
for column in columns:
if column.name == field.column:
found_add_field_migration = True
break
else:
return False, project_state
found_add_field_migration = True
# If we get this far and we found at least one CreateModel or AddField migration,
# the migration is considered implicitly applied.
return (found_create_model_migration or found_add_field_migration), after_state