Django Haystack update index faster - django

Question

I've been using Django Haystack for a while now and it's great! I have a rather heavy site with data which needs to be updated from time to time (15 to 30 mins).
When using the python manage.py update_index it takes lots of time to update the data. Is there a way to speed this up? Or maybe update only changed data if possible..
I'm currently using Django Haystack 1.2.7 with Solr as backend and Django 1.4.
Thanks!!!
EDIT:
Yes I've tried reading that part of the documentation but what I really need is a way to speed the indexing up. Maybe update only recent data instead of updating all. I've found get_updated_field but don't know how to use it. In the documentation it's only mentioned why it's used but no real examples are shown.
EDIT 2:
start = DateTimeField(model_attr='start', null=True, faceted=True, --HERE?--)
EDIT 3:
Ok i've implemented the solution bellow but when i tried rebuild_index (with 45000 data) it almost crashed my computer. After 10 mins of waiting an error appeared:
File "manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
utility.execute()
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 382, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 196, in run_from_argv
self.execute(*args, **options.__dict__)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 232, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python2.7/dist-packages/haystack/management/commands/rebuild_index.py", line 16, in handle
call_command('update_index', **options)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 150, in call_command
return klass.execute(*args, **defaults)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 232, in execute
output = self.handle(*args, **options)
File "/usr/local/lib/python2.7/dist-packages/haystack/management/commands/update_index.py", line 193, in handle
return super(Command, self).handle(*apps, **options)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 304, in handle
app_output = self.handle_app(app, **options)
File "/usr/local/lib/python2.7/dist-packages/haystack/management/commands/update_index.py", line 229, in handle_app
do_update(index, qs, start, end, total, self.verbosity)
File "/usr/local/lib/python2.7/dist-packages/haystack/management/commands/update_index.py", line 109, in do_update
index.backend.update(index, current_qs)
File "/usr/local/lib/python2.7/dist-packages/haystack/backends/solr_backend.py", line 73, in update
self.conn.add(docs, commit=commit, boost=index.get_field_weights())
File "/usr/local/lib/python2.7/dist-packages/pysolr.py", line 686, in add
m = ET.tostring(message, encoding='utf-8')
File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 1127, in tostring
ElementTree(element).write(file, encoding, method=method)
File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 821, in write
serialize(write, self._root, encoding, qnames, namespaces)
File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 940, in _serialize_xml
_serialize_xml(write, e, encoding, qnames, None)
File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 940, in _serialize_xml
_serialize_xml(write, e, encoding, qnames, None)
File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 915, in _serialize_xml
write("<" + tag)
MemoryError

Answer 1

get_updated_field should return a string that contains the name of the attribute on the model that contains the date that the model was updated (haystack docs). A DateField with auto_now=True would be ideal for that (Django docs).
For example, my UserProfile model has a field named updated
models.py
class UserProfile(models.Model):
user = models.ForeignKey(User)
# lots of other fields snipped
updated = models.DateTimeField(auto_now=True)
search_indexes.py
class UserProfileIndex(SearchIndex):
text = CharField(document=True, use_template=True)
user = CharField(model_attr='user')
user_fullname = CharField(model_attr='user__get_full_name')
def get_model(self):
return UserProfile
def get_updated_field(self):
return "updated"
Then when I run ./manage.py update_index --age=10 it only indexes the user profiles updated in the last 10 hours.