Author: russellm
Date: 2009-06-09 07:59:41 -0500 (Tue, 09 Jun 2009)
New Revision: 10966
Modified:
django/trunk/django/db/backends/creation.py
Log:
Fixed #9253 -- Modified the method used to generate constraint names so that it
is consistent regardless of machine word size.
NOTE: This change is backwards incompatible for some users.
If you are using a 32-bit platform, you will observe no differences as a
result of this change. However, users on 64-bit platforms may experience
some problems using the `reset` management command.
Prior to this change, 64-bit platforms would generate a 64-bit, 16 character
digest in the constraint name; for example:
ALTER TABLE `myapp_sometable` ADD CONSTRAINT
`object_id_refs_id_5e8f10c132091d1e` FOREIGN KEY ...
Following this change, all platforms, regardless of word size, will
generate a 32-bit, 8 character digest in the constraint name; for example:
ALTER TABLE `myapp_sometable` ADD CONSTRAINT `object_id_refs_id_32091d1e`
FOREIGN KEY ...
As a result of this change, you will not be able to use the `reset`
management command on any table created with 64-bit constraints. This
is because the the new generated name will not match the historically
generated name; as a result, the SQL constructed by the `reset` command
will be invalid.
If you need to reset an application that was created with 64-bit
constraints, you will need to manually drop the old constraint prior
to invoking `reset`.
Modified: django/trunk/django/db/backends/creation.py
===================================================================
--- django/trunk/django/db/backends/creation.py 2009-06-09 11:31:27 UTC (rev
10965)
+++ django/trunk/django/db/backends/creation.py 2009-06-09 12:59:41 UTC (rev
10966)
@@ -25,6 +25,10 @@
def __init__(self, connection):
self.connection = connection
+ def _digest(self, *args):
+ "Generate a 32 bit digest of a set of arguments that can be used to
shorten identifying names"
+ return '%x' % (abs(hash(args)) % (1<<32))
+
def sql_create_model(self, model, style, known_models=set()):
"""
Returns the SQL required to create a single model, as a tuple of:
@@ -128,7 +132,7 @@
col = opts.get_field(f.rel.field_name).column
# For MySQL, r_name must be unique in the first 64 characters.
# So we are careful with character usage here.
- r_name = '%s_refs_%s_%x' % (r_col, col, abs(hash((r_table,
table))))
+ r_name = '%s_refs_%s_%s' % (r_col, col, self._digest(r_table,
table))
final_output.append(style.SQL_KEYWORD('ALTER TABLE') + ' %s
ADD CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s)%s;' % \
(qn(r_table), qn(truncate_name(r_name,
self.connection.ops.max_name_length())),
qn(r_col), qn(table), qn(col),
@@ -187,8 +191,7 @@
output.append('\n'.join(table_output))
for r_table, r_col, table, col in deferred:
- r_name = '%s_refs_%s_%x' % (r_col, col,
- abs(hash((r_table, table))))
+ r_name = '%s_refs_%s_%s' % (r_col, col, self._digest(r_table,
table))
output.append(style.SQL_KEYWORD('ALTER TABLE') + ' %s ADD
CONSTRAINT %s FOREIGN KEY (%s) REFERENCES %s (%s)%s;' %
(qn(r_table),
qn(truncate_name(r_name,
self.connection.ops.max_name_length())),
@@ -289,7 +292,7 @@
col = f.column
r_table = model._meta.db_table
r_col = model._meta.get_field(f.rel.field_name).column
- r_name = '%s_refs_%s_%x' % (col, r_col, abs(hash((table,
r_table))))
+ r_name = '%s_refs_%s_%s' % (col, r_col, self._digest(table,
r_table))
output.append('%s %s %s %s;' % \
(style.SQL_KEYWORD('ALTER TABLE'),
style.SQL_TABLE(qn(table)),
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/django-updates?hl=en
-~----------~----~----~----~------~----~------~--~---
