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Code Issues 32 Releases Wiki Activity

[1.8.x] Fixed #24757 -- Recreated MySQL index when needed during combined index removal

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Thanks Thomas Recouvreux for the report and Tim Graham for the tests and
review.
Backport of ae635cc36 from master.
This commit is contained in:
Claude Paroz
2015-05-13 17:40:57 +02:00
parent 30e5703844
commit 6a0d9f068f
4 changed files with 70 additions and 18 deletions
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31
django/db/backends/base/schema.py
View File

@@ -317,15 +317,7 @@ class BaseDatabaseSchemaEditor(object):
news = set(tuple(fields) for fields in new_unique_together)
# Deleted uniques
for fields in olds.difference(news):
columns = [model._meta.get_field(field).column for field in fields]
constraint_names = self._constraint_names(model, columns, unique=True)
if len(constraint_names) != 1:
raise ValueError("Found wrong number (%s) of constraints for %s(%s)" % (
len(constraint_names),
model._meta.db_table,
", ".join(columns),
))
self.execute(self._delete_constraint_sql(self.sql_delete_unique, model, constraint_names[0]))
self._delete_composed_index(model, fields, {'unique': True}, self.sql_delete_unique)
# Created uniques
for fields in news.difference(olds):
columns = [model._meta.get_field(field).column for field in fields]
@@ -341,20 +333,23 @@ class BaseDatabaseSchemaEditor(object):
news = set(tuple(fields) for fields in new_index_together)
# Deleted indexes
for fields in olds.difference(news):
columns = [model._meta.get_field(field).column for field in fields]
constraint_names = self._constraint_names(model, list(columns), index=True)
if len(constraint_names) != 1:
raise ValueError("Found wrong number (%s) of constraints for %s(%s)" % (
len(constraint_names),
model._meta.db_table,
", ".join(columns),
))
self.execute(self._delete_constraint_sql(self.sql_delete_index, model, constraint_names[0]))
self._delete_composed_index(model, fields, {'index': True}, self.sql_delete_index)
# Created indexes
for field_names in news.difference(olds):
fields = [model._meta.get_field(field) for field in field_names]
self.execute(self._create_index_sql(model, fields, suffix="_idx"))
def _delete_composed_index(self, model, fields, constraint_kwargs, sql):
columns = [model._meta.get_field(field).column for field in fields]
constraint_names = self._constraint_names(model, columns, **constraint_kwargs)
if len(constraint_names) != 1:
raise ValueError("Found wrong number (%s) of constraints for %s(%s)" % (
len(constraint_names),
model._meta.db_table,
", ".join(columns),
))
self.execute(self._delete_constraint_sql(sql, model, constraint_names[0]))
def alter_db_table(self, model, old_db_table, new_db_table):
"""
Renames the table a model points to.

18
django/db/backends/mysql/schema.py
View File

@@ -62,6 +62,24 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
field.db_index = False
return super(DatabaseSchemaEditor, self)._model_indexes_sql(model)
def _delete_composed_index(self, model, fields, *args):
"""
MySQL can remove an implicit FK index on a field when that field is
covered by another index like a unique_together. "covered" here means
that the more complex index starts like the simpler one.
http://bugs.mysql.com/bug.php?id=37910 / Django ticket #24757
We check here before removing the [unique|index]_together if we have to
recreate a FK index.
"""
first_field = model._meta.get_field(fields[0])
if first_field.get_internal_type() == 'ForeignKey':
constraint_names = self._constraint_names(model, fields[0], index=True)
if not constraint_names:
self.execute(
self._create_index_sql(model, [model._meta.get_field(fields[0])], suffix="")
)
return super(DatabaseSchemaEditor, self)._delete_composed_index(model, fields, *args)
def _alter_column_type_sql(self, table, old_field, new_field, new_type):
# Keep null property of old field, if it has changed, it will be handled separately
if old_field.null: