diff --git a/rhodecode/controllers/compare.py b/rhodecode/controllers/compare.py
--- a/rhodecode/controllers/compare.py
+++ b/rhodecode/controllers/compare.py
@@ -25,7 +25,6 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 import logging
 import traceback
-import binascii
 
 from webob.exc import HTTPNotFound
 from pylons import request, response, session, tmpl_context as c, url
@@ -37,6 +36,7 @@ from rhodecode.lib.auth import LoginRequ
 from rhodecode.lib import diffs
 
 from rhodecode.model.db import Repository
+from rhodecode.model.pull_request import PullRequestModel
 
 log = logging.getLogger(__name__)
 
@@ -49,46 +49,6 @@ class CompareController(BaseRepoControll
     def __before__(self):
         super(CompareController, self).__before__()
 
-    def _get_discovery(self, org_repo, org_ref, other_repo, other_ref):
-        from mercurial import discovery
-        other = org_repo._repo
-        repo = other_repo._repo
-        tip = other[org_ref[1]]
-        log.debug('Doing discovery for %s@%s vs %s@%s' % (
-                        org_repo, org_ref, other_repo, other_ref)
-        )
-        log.debug('Filter heads are %s[%s]' % (tip, org_ref[1]))
-        tmp = discovery.findcommonincoming(
-                  repo=repo,  # other_repo we check for incoming
-                  remote=other,  # org_repo source for incoming
-                  heads=[tip.node()],
-                  force=False
-        )
-        return tmp
-
-    def _get_changesets(self, org_repo, org_ref, other_repo, other_ref, tmp):
-        changesets = []
-        #case two independent repos
-        if org_repo != other_repo:
-            common, incoming, rheads = tmp
-
-            if not incoming:
-                revs = []
-            else:
-                revs = org_repo._repo.changelog.findmissing(common, rheads)
-
-            for cs in reversed(map(binascii.hexlify, revs)):
-                changesets.append(org_repo.get_changeset(cs))
-        else:
-            revs = ['ancestors(%s) and not ancestors(%s)' % (org_ref[1],
-                                                             other_ref[1])]
-            from mercurial import scmutil
-            out = scmutil.revrange(org_repo._repo, revs)
-            for cs in reversed(out):
-                changesets.append(org_repo.get_changeset(cs))
-
-        return changesets
-
     def index(self, org_ref_type, org_ref, other_ref_type, other_ref):
 
         org_repo = c.rhodecode_db_repo.repo_name
@@ -108,15 +68,9 @@ class CompareController(BaseRepoControll
             log.error('Could not found repo %s or %s' % (org_repo, other_repo))
             raise HTTPNotFound
 
-        discovery_data = self._get_discovery(org_repo.scm_instance,
-                                           org_ref,
-                                           other_repo.scm_instance,
-                                           other_ref)
-        c.cs_ranges = self._get_changesets(org_repo.scm_instance,
-                                           org_ref,
-                                           other_repo.scm_instance,
-                                           other_ref,
-                                           discovery_data)
+        c.cs_ranges, discovery_data = PullRequestModel().get_compare_data(
+                                       org_repo, org_ref, other_repo, other_ref
+                                      )
 
         c.statuses = c.rhodecode_db_repo.statuses([x.raw_id for x in
                                                    c.cs_ranges])