diff --git a/pydruid/utils/dimensions.py b/pydruid/utils/dimensions.py
new file mode 100644
index 00000000..13ed4c4b
--- /dev/null
+++ b/pydruid/utils/dimensions.py
@@ -0,0 +1,114 @@
+def build_dimension(dim):
+    if isinstance(dim, DimensionSpec):
+        dim = dim.build()
+
+    return dim
+
+
+class DimensionSpec(object):
+
+    def __init__(self, dimension, output_name, extraction_function=None):
+        self._dimension = dimension
+        self._output_name = output_name
+        self._extraction_function = extraction_function
+
+    def build(self):
+        dimension_spec = {
+            'type': 'default',
+            'dimension': self._dimension,
+            'outputName': self._output_name
+        }
+
+        if self._extraction_function is not None:
+            dimension_spec['type'] = 'extraction'
+            dimension_spec['extractionFn'] = self._extraction_function.build()
+
+        return dimension_spec
+
+
+class ExtractionFunction(object):
+
+    extraction_type = None
+
+    def build(self):
+        return {'type': self.extraction_type}
+
+
+class BaseRegexExtraction(ExtractionFunction):
+
+    def __init__(self, expr):
+        super(BaseRegexExtraction, self).__init__()
+        self._expr = expr
+
+    def build(self):
+        extractor = super(BaseRegexExtraction, self).build()
+        extractor['expr'] = self._expr
+
+        return extractor
+
+
+class RegexExtraction(BaseRegexExtraction):
+
+    extraction_type = 'regex'
+
+
+class PartialExtraction(BaseRegexExtraction):
+
+    extraction_type = 'partial'
+
+
+class JavascriptExtraction(ExtractionFunction):
+
+    extraction_type = 'javascript'
+
+    def __init__(self, func, injective=False):
+        super(JavascriptExtraction, self).__init__()
+        self._func = func
+        self._injective = injective
+
+    def build(self):
+        extractor = super(JavascriptExtraction, self).build()
+        extractor['function'] = self._func
+        extractor['injective'] = self._injective
+
+        return extractor
+
+
+class LookupExtraction(ExtractionFunction):
+
+    extraction_type = 'lookup'
+    lookup_type = None
+
+    def __init__(self, retain_missing_values=False,
+                 replace_missing_values=None, injective=False):
+        super(LookupExtraction, self).__init__()
+        self._retain_missing_values = retain_missing_values
+        self._replace_missing_values = replace_missing_values
+        self._injective = injective
+
+    def build(self):
+        extractor = super(LookupExtraction, self).build()
+        extractor['lookup'] = self.build_lookup()
+        extractor['retainMissingValue'] = self._retain_missing_values
+        extractor['replaceMissingValueWith'] = self._replace_missing_values
+        extractor['injective'] = self._injective
+
+        return extractor
+
+    def build_lookup(self):
+        return {'type': self.lookup_type}
+
+
+class MapLookupExtraction(LookupExtraction):
+
+    lookup_type = 'map'
+
+    def __init__(self, mapping, **kwargs):
+        super(MapLookupExtraction, self).__init__(**kwargs)
+        self._mapping = mapping
+
+    def build_lookup(self):
+        lookup = super(MapLookupExtraction, self).build_lookup()
+        lookup['map'] = self._mapping
+
+        return lookup