diff --git a/cloudkitty/collector/gnocchi.py b/cloudkitty/collector/gnocchi.py
index 7df254bf..da17d400 100644
--- a/cloudkitty/collector/gnocchi.py
+++ b/cloudkitty/collector/gnocchi.py
@@ -114,6 +114,21 @@ GNOCCHI_EXTRA_SCHEMA = {
             In(BASIC_AGGREGATION_METHODS),
         Required('force_granularity', default=3600): All(int, Range(min=0)),
         Required('use_all_resource_revisions', default=True): All(bool),
+        # Provide means for operators to customize the aggregation query
+        # executed against Gnocchi. By default we use the following:
+        #
+        # '(aggregate RE_AGGREGATION_METHOD
+        #   (metric METRIC_NAME AGGREGATION_METHOD))'
+        #
+        # Therefore, this option enables operators to take full advantage of
+        # operations available in Gnocchi, such as any arithmetic operations,
+        # logical operations and many others.
+        #
+        # When using a custom aggregation query, you can keep the placeholders
+        # 'RE_AGGREGATION_METHOD', 'AGGREGATION_METHOD', and 'METRIC_NAME':
+        # they will be replaced at runtime by values from the metric
+        # configuration.
+        Required('custom_query', default=''): All(str),
     },
 }
 
@@ -369,9 +384,32 @@ class GnocchiCollector(collector.BaseCollector):
     def build_operation_command(self, metric_name):
         extra_args = self.conf[metric_name]['extra_args']
 
-        re_aggregation_method = extra_args['re_aggregation_method']
+        op = self.generate_aggregation_operation(extra_args, metric_name)
+
+        LOG.debug("Aggregation operation [%s] used to retrieve metric [%s].",
+                  op, metric_name)
+        return op
+
+    @staticmethod
+    def generate_aggregation_operation(extra_args, metric_name):
+        aggregation_method = extra_args['aggregation_method']
+        re_aggregation_method = aggregation_method
+
+        if 're_aggregation_method' in extra_args:
+            re_aggregation_method = extra_args['re_aggregation_method']
+
         op = ["aggregate", re_aggregation_method,
-              ["metric", metric_name, extra_args['aggregation_method']]]
+              ["metric", metric_name, aggregation_method]]
+
+        custom_gnocchi_query = extra_args.get('custom_query')
+        if custom_gnocchi_query:
+            LOG.debug("Using custom Gnocchi query [%s] with metric [%s].",
+                      custom_gnocchi_query, metric_name)
+            op = custom_gnocchi_query.replace(
+                'RE_AGGREGATION_METHOD', re_aggregation_method).replace(
+                'AGGREGATION_METHOD', aggregation_method).replace(
+                'METRIC_NAME', metric_name)
+
         return op
 
     def _format_data(self, metconf, data, resources_info=None):
diff --git a/cloudkitty/tests/collectors/test_gnocchi.py b/cloudkitty/tests/collectors/test_gnocchi.py
index 6600ae82..9f16382e 100644
--- a/cloudkitty/tests/collectors/test_gnocchi.py
+++ b/cloudkitty/tests/collectors/test_gnocchi.py
@@ -262,3 +262,41 @@ class GnocchiCollectorAggregationOperationTest(tests.TestCase):
         data_filtered = list(data_filtered)
         self.assertEqual(1, len(data_filtered))
         self.assertEqual(expected_data, data_filtered[0])
+
+    def test_generate_aggregation_operation_same_reaggregation(self):
+        metric_name = "test"
+        extra_args = {"aggregation_method": 'mean'}
+
+        expected_op = ["aggregate", 'mean', ["metric", "test", 'mean']]
+
+        op = gnocchi.GnocchiCollector.generate_aggregation_operation(
+            extra_args, metric_name)
+
+        self.assertEqual(expected_op, op)
+
+    def test_generate_aggregation_operation_different_reaggregation(self):
+        metric_name = "test"
+        extra_args = {"aggregation_method": 'mean',
+                      "re_aggregation_method": 'max'}
+
+        expected_op = ["aggregate", 'max', ["metric", "test", 'mean']]
+
+        op = gnocchi.GnocchiCollector.generate_aggregation_operation(
+            extra_args, metric_name)
+
+        self.assertEqual(expected_op, op)
+
+    def test_generate_aggregation_operation_custom_query(self):
+        metric_name = "test"
+        extra_args = {"aggregation_method": 'mean',
+                      "re_aggregation_method": 'max',
+                      "custom_query":
+                          "(* (aggregate RE_AGGREGATION_METHOD (metric "
+                          "METRIC_NAME AGGREGATION_METHOD)) -1)"}
+
+        expected_op = "(* (aggregate max (metric test mean)) -1)"
+
+        op = gnocchi.GnocchiCollector.generate_aggregation_operation(
+            extra_args, metric_name)
+
+        self.assertEqual(expected_op, op)
diff --git a/cloudkitty/tests/collectors/test_validation.py b/cloudkitty/tests/collectors/test_validation.py
index c62974f3..bd08526d 100644
--- a/cloudkitty/tests/collectors/test_validation.py
+++ b/cloudkitty/tests/collectors/test_validation.py
@@ -69,9 +69,13 @@ class MetricConfigValidationTest(tests.TestCase):
         expected_output = copy.deepcopy(self.base_output)
         expected_output['metric_one']['groupby'] += ['project_id', 'id']
         expected_output['metric_one']['extra_args'] = {
-            'aggregation_method': 'max', 're_aggregation_method': 'max',
-            'force_granularity': 3600, 'resource_type': 'res',
-            'resource_key': 'id', 'use_all_resource_revisions': True}
+            'aggregation_method': 'max',
+            're_aggregation_method': 'max',
+            'force_granularity': 3600,
+            'resource_type': 'res',
+            'resource_key': 'id',
+            'use_all_resource_revisions': True,
+            'custom_query': ''}
 
         self.assertEqual(
             collector.gnocchi.GnocchiCollector.check_configuration(data),
diff --git a/doc/source/admin/configuration/collector.rst b/doc/source/admin/configuration/collector.rst
index e77c1c27..9291b631 100644
--- a/doc/source/admin/configuration/collector.rst
+++ b/doc/source/admin/configuration/collector.rst
@@ -1,3 +1,4 @@
+
 =========================
  Collector configuration
 =========================
@@ -307,6 +308,24 @@ Gnocchi
   CloudKitty for a resource id. The default behavior is maintained, which
   means, CloudKitty always use all of the data points returned.
 
+* ``custom_query``: Provide means for operators to customize the aggregation
+  query executed against Gnocchi. By default we use the following ``(aggregate
+  RE_AGGREGATION_METHOD (metric METRIC_NAME AGGREGATION_METHOD))``. Therefore,
+  this option enables operators to take full advantage of operations available
+  in Gnocchi such as any arithmetic operations, logical operations and many
+  others. When using a custom aggregation query, you can keep the placeholders
+  ``RE_AGGREGATION_METHOD``, ``AGGREGATION_METHOD``, and ``METRIC_NAME``: they
+  will be replaced at runtime by values from the metric configuration.
+
+  One example use case is metrics that are supposed to be always growing
+  values, such as RadosGW usage data. The usage data is affected by usage data
+  trimming on RadosGW, which can lead to swaps (meaning, that the right side
+  value of the series is smaller than the left side value) in the data series
+  in Gnocchi. Therefore, to handle this situation one could, for instance, use
+  the following custom query: ``(div (+ (aggregate RE_AGGREGATION_METHOD
+  (metric METRIC_NAME AGGREGATION_METHOD)) (abs (aggregate
+  RE_AGGREGATION_METHOD (metric METRIC_NAME AGGREGATION_METHOD)))) 2)``: this
+  custom query would return ``0`` when the value of the series swap.
 
 Monasca
 ~~~~~~~
diff --git a/releasenotes/notes/custom-gnocchi-query-a391f5e83d55d771.yaml b/releasenotes/notes/custom-gnocchi-query-a391f5e83d55d771.yaml
new file mode 100644
index 00000000..beb4a0d2
--- /dev/null
+++ b/releasenotes/notes/custom-gnocchi-query-a391f5e83d55d771.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Enable using custom queries with the Gnocchi collector. This option enables
+    operators to take full advantage of the operations that are available on
+    Gnocchi such as any arithmetic operation, logical operation and many
+    others.