Back to Top

Wednesday, August 15, 2012

Clearing your Google App Engine datastore

Warning! This is a method to erase the data from your Google App Engine datastore. There is no way to recover your data after you go trough with this! Only use this if you're absolutely certain!

If you have a GAE account used for experimentation, you might like to clean it up sometimes (erase the contents of the datastore and blobstore associated with the application). Doing this trough the admin interface can become very tedious, so here is an alternative method:

  1. Start your Remote API shell
  2. Use the following code to delete all datastore entities:
    while True: keys=db.Query(keys_only=True).fetch(500); db.delete(keys); print "Deleted 500 entries, the last of which was %s" % keys[-1].to_path()
  3. Use the following code to delete all blobstore entities:
    from google.appengine.ext.blobstore import *
    while True: list=BlobInfo.all().fetch(500); delete([b.key() for b in list]);  print "Deleted elements, the last of which was %s" % list[-1].filename

The above method is inspired by this stackoverflow answer, but has the advantage that it does the deletion in smaller steps, meaning that the risk of the entire transaction being aborted because of deadline exceeded or over quota errors is removed.

Final caveats:

  • This can be slow
  • This consumes your quota, so you might have to do it over several days or raise your quota
  • The code is written in a very non-pythonic way (multiple statements on one line) for the ease of copy-pasting


Post a Comment

You can use some HTML tags, such as <b>, <i>, <a>. Comments are moderated, so there will be a delay until the comment appears. However if you comment, I follow.