Add support for pushing dataframes to Presto databases.

Closes #112

pyhive/sqlalchemy_hive.py

@@ -129,7 +129,7 @@ class HiveCompiler(SQLCompiler):
         return 'length{}'.format(self.function_argspec(fn, **kw))
 
 
-if StrictVersion(sqlalchemy.__version__) >= StrictVersion('0.6.0'):
+if StrictVersion(sqlalchemy.__version__) >= StrictVersion('0.7.0'):
     class HiveTypeCompiler(compiler.GenericTypeCompiler):
         def visit_INTEGER(self, type_):
             return 'INT'

pyhive/sqlalchemy_presto.py

@@ -189,6 +189,7 @@ class PrestoDialect(default.DefaultDialect):
         # requests gives back Unicode strings
         return True
 
+
 if StrictVersion(sqlalchemy.__version__) < StrictVersion('0.7.0'):
     from pyhive import sqlalchemy_backports
 
@@ -196,3 +197,24 @@ if StrictVersion(sqlalchemy.__version__) < StrictVersion('0.7.0'):
         insp = sqlalchemy_backports.Inspector.from_engine(connection)
         return insp.reflecttable(table, include_columns, exclude_columns)
     PrestoDialect.reflecttable = reflecttable
+else:
+    class PrestoTypeCompiler(compiler.GenericTypeCompiler):
+        def visit_CLOB(self, type_, **kw):
+            raise ValueError("Presto does not support the CLOB column type.")
+
+        def visit_NCLOB(self, type_, **kw):
+            raise ValueError("Presto does not support the NCLOB column type.")
+
+        def visit_DATETIME(self, type_, **kw):
+            raise ValueError("Presto does not support the DATETIME column type.")
+
+        def visit_FLOAT(self, type_, **kw):
+            return 'DOUBLE'
+
+        def visit_TEXT(self, type_, **kw):
+            if type_.length:
+                return 'VARCHAR({:d})'.format(type_.length)
+            else:
+                return 'VARCHAR'
+
+    PrestoDialect.type_compiler = PrestoTypeCompiler