Support for Presto decimals (dropbox#430)

* Support for Presto decimals

* lower

pyhive/presto.py

@@ -9,6 +9,8 @@
 from __future__ import unicode_literals
 
 from builtins import object
+from decimal import Decimal
+
 from pyhive import common
 from pyhive.common import DBAPITypeObject
 # Make all exceptions visible in this module per DB-API
@@ -34,6 +36,11 @@
 
 _logger = logging.getLogger(__name__)
 
+TYPES_CONVERTER = {
+    "decimal": Decimal,
+    # As of Presto 0.69, binary data is returned as the varbinary type in base64 format
+    "varbinary": base64.b64decode
+}
 
 class PrestoParamEscaper(common.ParamEscaper):
     def escape_datetime(self, item, format):
@@ -307,14 +314,13 @@ def _fetch_more(self):
         """Fetch the next URI and update state"""
         self._process_response(self._requests_session.get(self._nextUri, **self._requests_kwargs))
 
-    def _decode_binary(self, rows):
-        # As of Presto 0.69, binary data is returned as the varbinary type in base64 format
-        # This function decodes base64 data in place
+    def _process_data(self, rows):
         for i, col in enumerate(self.description):
-            if col[1] == 'varbinary':
+            col_type = col[1].split("(")[0].lower()
+            if col_type in TYPES_CONVERTER:
                 for row in rows:
                     if row[i] is not None:
-                        row[i] = base64.b64decode(row[i])
+                        row[i] = TYPES_CONVERTER[col_type](row[i])
 
     def _process_response(self, response):
         """Given the JSON response from Presto's REST API, update the internal state with the next
@@ -341,7 +347,7 @@ def _process_response(self, response):
         if 'data' in response_json:
             assert self._columns
             new_data = response_json['data']
-            self._decode_binary(new_data)
+            self._process_data(new_data)
             self._data += map(tuple, new_data)
         if 'nextUri' not in response_json:
             self._state = self._STATE_FINISHED

pyhive/tests/test_presto.py

@@ -9,6 +9,8 @@
 
 import contextlib
 import os
+from decimal import Decimal
+
 import requests
 
 from pyhive import exc
@@ -93,7 +95,7 @@ def test_complex(self, cursor):
             {"1": 2, "3": 4},  # Presto converts all keys to strings so that they're valid JSON
             [1, 2],  # struct is returned as a list of elements
             # '{0:1}',
-            '0.1',
+            Decimal('0.1'),
         )]
         self.assertEqual(rows, expected)
         # catch unicode/str

pyhive/tests/test_trino.py

@@ -9,6 +9,8 @@
 
 import contextlib
 import os
+from decimal import Decimal
+
 import requests
 
 from pyhive import exc
@@ -89,7 +91,7 @@ def test_complex(self, cursor):
             {"1": 2, "3": 4},  # Trino converts all keys to strings so that they're valid JSON
             [1, 2],  # struct is returned as a list of elements
             # '{0:1}',
-            '0.1',
+            Decimal('0.1'),
         )]
         self.assertEqual(rows, expected)
         # catch unicode/str

pyhive/trino.py

@@ -124,7 +124,7 @@ def _process_response(self, response):
         if 'data' in response_json:
             assert self._columns
             new_data = response_json['data']
-            self._decode_binary(new_data)
+            self._process_data(new_data)
             self._data += map(tuple, new_data)
         if 'nextUri' not in response_json:
             self._state = self._STATE_FINISHED