[PATCH 2/4] migrations: 0043_merge_patch_submission: do less work

Daniel Axtens dja at axtens.net
Sat Jul 17 03:19:38 AEST 2021


 - we do a lot of legwork to prevent there being a column with the same
   name in a base class and subclass. This is purely for django's benefit
   as databases don't see the class relationship and handle column names
   being the same across tables just fine. Unfortunately renaming columns
   in MySQL/MariaDB is _extremely_ expensive. So just don't do it: lie to
   django about the names of the duplicate columns.

 - This means we don't have to worry about deleting the index and the
   unique_together constraints. Let deleting the table do all of that at
   once.

 - I don't think we gain anything from deleting foreign keys out of the
   patch table before deleting it. I initially thought this might relate
   to an ON DELETE CASCADE, but the ON DELETE rules in the patches table
   relate to what happens to the row in the patches tables if you delete
   an element from the associated table, not the other way around.

Signed-off-by: Daniel Axtens <dja at axtens.net>
---
 .../migrations/0043_merge_patch_submission.py | 140 +++++++++---------
 1 file changed, 68 insertions(+), 72 deletions(-)

diff --git a/patchwork/migrations/0043_merge_patch_submission.py b/patchwork/migrations/0043_merge_patch_submission.py
index d351892ef7f2..465e527812ba 100644
--- a/patchwork/migrations/0043_merge_patch_submission.py
+++ b/patchwork/migrations/0043_merge_patch_submission.py
@@ -10,16 +10,16 @@ def migrate_data(apps, schema_editor):
         schema_editor.execute(
             """
             UPDATE patchwork_submission
-              SET archived = patchwork_patch.archived2,
-                  commit_ref = patchwork_patch.commit_ref2,
-                  delegate_id = patchwork_patch.delegate2_id,
-                  diff = patchwork_patch.diff2,
-                  hash = patchwork_patch.hash2,
-                  number = patchwork_patch.number2,
-                  pull_url = patchwork_patch.pull_url2,
-                  related_id = patchwork_patch.related2_id,
-                  series_id = patchwork_patch.series2_id,
-                  state_id = patchwork_patch.state2_id
+              SET archived = patchwork_patch.archived,
+                  commit_ref = patchwork_patch.commit_ref,
+                  delegate_id = patchwork_patch.delegate_id,
+                  diff = patchwork_patch.diff,
+                  hash = patchwork_patch.hash,
+                  number = patchwork_patch.number,
+                  pull_url = patchwork_patch.pull_url,
+                  related_id = patchwork_patch.related_id,
+                  series_id = patchwork_patch.series_id,
+                  state_id = patchwork_patch.state_id
             FROM patchwork_patch
               WHERE patchwork_submission.id = patchwork_patch.submission_ptr_id
             """
@@ -28,16 +28,16 @@ def migrate_data(apps, schema_editor):
         schema_editor.execute(
             """
             UPDATE patchwork_submission, patchwork_patch
-              SET patchwork_submission.archived = patchwork_patch.archived2,
-                  patchwork_submission.commit_ref = patchwork_patch.commit_ref2,
-                  patchwork_submission.delegate_id = patchwork_patch.delegate2_id,
-                  patchwork_submission.diff = patchwork_patch.diff2,
-                  patchwork_submission.hash = patchwork_patch.hash2,
-                  patchwork_submission.number = patchwork_patch.number2,
-                  patchwork_submission.pull_url = patchwork_patch.pull_url2,
-                  patchwork_submission.related_id = patchwork_patch.related2_id,
-                  patchwork_submission.series_id = patchwork_patch.series2_id,
-                  patchwork_submission.state_id = patchwork_patch.state2_id
+              SET patchwork_submission.archived = patchwork_patch.archived,
+                  patchwork_submission.commit_ref = patchwork_patch.commit_ref,
+                  patchwork_submission.delegate_id = patchwork_patch.delegate_id,
+                  patchwork_submission.diff = patchwork_patch.diff,
+                  patchwork_submission.hash = patchwork_patch.hash,
+                  patchwork_submission.number = patchwork_patch.number,
+                  patchwork_submission.pull_url = patchwork_patch.pull_url,
+                  patchwork_submission.related_id = patchwork_patch.related_id,
+                  patchwork_submission.series_id = patchwork_patch.series_id,
+                  patchwork_submission.state_id = patchwork_patch.state_id
             WHERE patchwork_submission.id = patchwork_patch.submission_ptr_id
             """  # noqa
         )
@@ -50,16 +50,16 @@ def migrate_data(apps, schema_editor):
                 pull_url, related_id, series_id, state_id
               ) = (
                 SELECT
-                  patchwork_patch.archived2,
-                  patchwork_patch.commit_ref2,
-                  patchwork_patch.delegate2_id,
-                  patchwork_patch.diff2,
-                  patchwork_patch.hash2,
-                  patchwork_patch.number2,
-                  patchwork_patch.pull_url2,
-                  patchwork_patch.related2_id,
-                  patchwork_patch.series2_id,
-                  patchwork_patch.state2_id
+                  patchwork_patch.archived,
+                  patchwork_patch.commit_ref,
+                  patchwork_patch.delegate_id,
+                  patchwork_patch.diff,
+                  patchwork_patch.hash,
+                  patchwork_patch.number,
+                  patchwork_patch.pull_url,
+                  patchwork_patch.related_id,
+                  patchwork_patch.series_id,
+                  patchwork_patch.state_id
                 FROM patchwork_patch
                 WHERE patchwork_patch.submission_ptr_id = patchwork_submission.id
               )
@@ -152,39 +152,44 @@ class Migration(migrations.Migration):
         # rename all the fields on 'Patch' so we don't have duplicates when we
         # add them to 'Submission'
 
-        migrations.RemoveIndex(
-            model_name='patch', name='patch_list_covering_idx',
-        ),
-        migrations.AlterUniqueTogether(name='patch', unique_together=set([]),),
-        migrations.RenameField(
-            model_name='patch', old_name='archived', new_name='archived2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='commit_ref', new_name='commit_ref2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='delegate', new_name='delegate2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='diff', new_name='diff2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='hash', new_name='hash2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='number', new_name='number2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='pull_url', new_name='pull_url2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='related', new_name='related2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='series', new_name='series2',
-        ),
-        migrations.RenameField(
-            model_name='patch', old_name='state', new_name='state2',
+        # Again we only to rename these fields in the django view of the world (state)
+        # to avoid errors about the same fields being in the base class (Submission)
+        # and a subclass (Patch). The db doesn't care, and we migrate the data in raw
+        # SQL, so basically just lie to django here.
+        migrations.SeparateDatabaseAndState(
+            database_operations=[],
+            state_operations=[
+                migrations.RenameField(
+                    model_name='patch', old_name='archived', new_name='archived2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='commit_ref', new_name='commit_ref2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='delegate', new_name='delegate2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='diff', new_name='diff2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='hash', new_name='hash2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='number', new_name='number2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='pull_url', new_name='pull_url2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='related', new_name='related2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='series', new_name='series2',
+                ),
+                migrations.RenameField(
+                    model_name='patch', old_name='state', new_name='state2',
+                ),
+            ],
         ),
 
         # add the fields found on 'Patch' to 'Submission'
@@ -306,15 +311,6 @@ class Migration(migrations.Migration):
             ),
         ),
 
-        # remove the foreign key fields from the 'Patch' model
-
-        migrations.RemoveField(model_name='patch', name='delegate2',),
-        migrations.RemoveField(model_name='patch', name='patch_project',),
-        migrations.RemoveField(model_name='patch', name='related2',),
-        migrations.RemoveField(model_name='patch', name='series2',),
-        migrations.RemoveField(model_name='patch', name='state2',),
-        migrations.RemoveField(model_name='patch', name='submission_ptr',),
-
         # drop the 'Patch' model and rename 'Submission' to 'Patch'
 
         migrations.DeleteModel(name='Patch',),
-- 
2.30.2



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