Re-enable parent id backfill, use new backfill style

util/migrate/backfill_parent_id.py

@@ -1,46 +1,38 @@
 import logging
-from data.database import Image, ImageStorage, db
+
+from data.database import Image, ImageStorage, db, db_for_update
 from app import app
+from util.migrate import yield_random_entries
+
 
 logger = logging.getLogger(__name__)
 
+
 def backfill_parent_id():
   logger.setLevel(logging.DEBUG)
 
   logger.debug('backfill_parent_id: Starting')
   logger.debug('backfill_parent_id: This can be a LONG RUNNING OPERATION. Please wait!')
 
-  # Check for any images without parent
-  has_images = bool(list(Image
-                         .select(Image.id)
-                         .join(ImageStorage)
-                         .where(Image.parent >> None, Image.ancestors != '/', ImageStorage.uploading == False)
-                         .limit(1)))
+  def fetch_batch():
+    return (Image
+            .select(Image.id, Image.ancestors)
+            .join(ImageStorage)
+            .where(Image.parent >> None, Image.ancestors != '/',
+                   ImageStorage.uploading == False))
 
-  if not has_images:
-    logger.debug('backfill_parent_id: No migration needed')
-    return
+  for to_backfill in yield_random_entries(fetch_batch, 10000, 0.3):
+    with app.config['DB_TRANSACTION_FACTORY'](db):
+      try:
+        image = db_for_update(Image
+                              .select()
+                              .where(Image.id == to_backfill.id)).get()
+        image.parent = to_backfill.ancestors.split('/')[-2]
+        image.save()
+      except Image.DoesNotExist:
+        pass
 
-  while True:
-    # Load the record from the DB.
-    batch_images_ids = list(Image
-                            .select(Image.id)
-                            .join(ImageStorage)
-                            .where(Image.parent >> None, Image.ancestors != '/', ImageStorage.uploading == False)
-                            .limit(100))
-
-    if len(batch_images_ids) == 0:
-      logger.debug('backfill_parent_id: Completed')
-      return
-
-    for image_id in batch_images_ids:
-      with app.config['DB_TRANSACTION_FACTORY'](db):
-        try:
-          image = Image.select(Image.id, Image.ancestors).where(Image.id == image_id).get()
-          image.parent = image.ancestors.split('/')[-2]
-          image.save()
-        except Image.DoesNotExist:
-          pass
+  logger.debug('backfill_parent_id: Completed')
 
 if __name__ == "__main__":
   logging.basicConfig(level=logging.DEBUG)