diff --git a/README.rst b/README.rst
index 1660254..0a6466b 100644
--- a/README.rst
+++ b/README.rst
@@ -151,6 +151,11 @@ field. The currently supported configuration options are:
     created from this harvesting source. Logged in users and visitors will be
     only able to read them.
 
+*   force_all: By default, after the first harvesting, the harvester will gather
+    only the modified packages from the remote site since the last harvesting.
+    Setting this property to true will force the harvester to gather all remote
+    packages regardless of the modification date. Default is False.
+
 Here is an example of a configuration object (the one that must be entered in
 the configuration field)::
 
diff --git a/ckanext/harvest/harvesters/ckanharvester.py b/ckanext/harvest/harvesters/ckanharvester.py
index 7e293e4..8a3c5fc 100644
--- a/ckanext/harvest/harvesters/ckanharvester.py
+++ b/ckanext/harvest/harvesters/ckanharvester.py
@@ -99,6 +99,11 @@ class CKANHarvester(HarvesterBase):
                 except NotFound,e:
                     raise ValueError('User not found')
 
+            for key in ('read_only','force_all'):
+                if key in config_obj:
+                    if not isinstance(config_obj[key],bool):
+                        raise ValueError('%s must be boolean' % key)
+
         except ValueError,e:
             raise e
 
@@ -125,7 +130,8 @@ class CKANHarvester(HarvesterBase):
         base_rest_url = base_url + self._get_rest_api_offset()
         base_search_url = base_url + self._get_search_api_offset()
 
-        if previous_job and not previous_job.gather_errors and not len(previous_job.objects) == 0:
+        if (previous_job and not previous_job.gather_errors and not len(previous_job.objects) == 0) \
+           or not self.config.get('force_all',False):
             get_all_packages = False
 
             # Request only the packages modified since last harvest job