models: Add covering index for Patch.hash

Signed-off-by: Stephen Finucane <[email protected]>
Closes: #579
Cc: Mauro Carvalho Chehab <[email protected]>

Author: stephenfin

patchwork/migrations/0047_add_database_indexes.py

@@ -0,0 +1,18 @@
+import patchwork.fields
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('patchwork', '0046_patch_comment_events'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='patch',
+            name='hash',
+            field=patchwork.fields.HashField(
+                blank=True, db_index=True, max_length=40, null=True
+            ),
+        ),
+    ]

patchwork/models.py

@@ -501,7 +501,7 @@ class Patch(SubmissionMixin):
     )
     state = models.ForeignKey(State, null=True, on_delete=models.CASCADE)
     archived = models.BooleanField(default=False)
-    hash = HashField(null=True, blank=True)
+    hash = HashField(null=True, blank=True, db_index=True)
 
     # series metadata