6 files changed, 13 insertions, 106 deletions
diff --git a/lib/sqlalchemy/dialects/firebird/base.py b/lib/sqlalchemy/dialects/firebird/base.py
index 21fec6b51..86d6876a6 100644
--- a/lib/sqlalchemy/dialects/firebird/base.py
+++ b/lib/sqlalchemy/dialects/firebird/base.py
@@ -123,29 +123,7 @@ RESERVED_WORDS = set([
     ])
 
 
-class _FBBoolean(sqltypes.Boolean):
-    def result_processor(self, dialect, coltype):
-        def process(value):
-            if value is None:
-                return None
-            return value and True or False
-        return process
-
-    def bind_processor(self, dialect):
-        def process(value):
-            if value is True:
-                return 1
-            elif value is False:
-                return 0
-            elif value is None:
-                return None
-            else:
-                return value and True or False
-        return process
-
-
 colspecs = {
-    sqltypes.Boolean: _FBBoolean,
 }
 
 ischema_names = {
@@ -321,10 +299,13 @@ class FBDialect(default.DefaultDialect):
     sequences_optional = False
     supports_default_values = True
     postfetch_lastrowid = False
-
+    
+    supports_native_boolean = False
+    
     requires_name_normalize = True
     supports_empty_insert = False
 
+    
     statement_compiler = FBCompiler
     ddl_compiler = FBDDLCompiler
     preparer = FBIdentifierPreparer
diff --git a/lib/sqlalchemy/dialects/mssql/base.py b/lib/sqlalchemy/dialects/mssql/base.py
index bd275d758..1060446b2 100644
--- a/lib/sqlalchemy/dialects/mssql/base.py
+++ b/lib/sqlalchemy/dialects/mssql/base.py
@@ -604,25 +604,6 @@ class IMAGE(sqltypes.Binary):
 class BIT(sqltypes.TypeEngine):
     __visit_name__ = 'BIT'
     
-class _MSBoolean(sqltypes.Boolean):
-    def result_processor(self, dialect, coltype):
-        def process(value):
-            if value is None:
-                return None
-            return value and True or False
-        return process
-
-    def bind_processor(self, dialect):
-        def process(value):
-            if value is True:
-                return 1
-            elif value is False:
-                return 0
-            elif value is None:
-                return None
-            else:
-                return value and True or False
-        return process
 
 class MONEY(sqltypes.TypeEngine):
     __visit_name__ = 'MONEY'
@@ -640,7 +621,6 @@ class SQL_VARIANT(sqltypes.TypeEngine):
 MSNumeric = _MSNumeric
 MSDateTime = _MSDateTime
 MSDate = _MSDate
-MSBoolean = _MSBoolean
 MSReal = REAL
 MSTinyInteger = TINYINT
 MSTime = TIME
@@ -667,7 +647,6 @@ colspecs = {
     sqltypes.DateTime : _MSDateTime,
     sqltypes.Date : _MSDate,
     sqltypes.Time : TIME,
-    sqltypes.Boolean : _MSBoolean,
 }
 
 ischema_names = {
@@ -1137,6 +1116,7 @@ class MSDialect(default.DefaultDialect):
     colspecs = colspecs
     ischema_names = ischema_names
     
+    supports_native_boolean = False
     supports_unicode_binds = True
     postfetch_lastrowid = True
     
diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index 3a2773892..01f8b13a7 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -167,6 +167,13 @@ available.
 
       update(..., mysql_limit=10)
 
+Boolean Types
+-------------
+
+MySQL's BOOL type is a synonym for SMALLINT, so is actually a numeric value,
+and additionally MySQL doesn't support CHECK constraints. Therefore SQLA's
+Boolean type cannot fully constrain values to just "True" and "False" the way it does for most other backends.
+
 Troubleshooting
 ---------------
 
@@ -1080,32 +1087,7 @@ class SET(_StringType):
                 return value
         return process
 
-class _MSBoolean(sqltypes.Boolean):
-    """MySQL BOOLEAN type."""
-
-    __visit_name__ = 'BOOLEAN'
-
-    def result_processor(self, dialect, coltype):
-        def process(value):
-            if value is None:
-                return None
-            return value and True or False
-        return process
-
-    def bind_processor(self, dialect):
-        def process(value):
-            if value is True:
-                return 1
-            elif value is False:
-                return 0
-            elif value is None:
-                return None
-            else:
-                return value and True or False
-        return process
-
 # old names
-MSBoolean = _MSBoolean
 MSTime = _MSTime
 MSSet = SET
 MSEnum = ENUM
@@ -1141,7 +1123,6 @@ colspecs = {
     sqltypes.Numeric: NUMERIC,
     sqltypes.Float: FLOAT,
     sqltypes.Binary: _BinaryType,
-    sqltypes.Boolean: _MSBoolean,
     sqltypes.Time: _MSTime,
     sqltypes.Enum: ENUM,
 }
@@ -1656,7 +1637,6 @@ class MySQLDialect(default.DefaultDialect):
     max_identifier_length = 255
     
     supports_native_enum = True
-    supports_native_boolean = True
     
     supports_sane_rowcount = True
     supports_sane_multi_rowcount = False
diff --git a/lib/sqlalchemy/dialects/oracle/base.py b/lib/sqlalchemy/dialects/oracle/base.py
index d13e37d60..ddcc9f460 100644
--- a/lib/sqlalchemy/dialects/oracle/base.py
+++ b/lib/sqlalchemy/dialects/oracle/base.py
@@ -158,25 +158,6 @@ class LONG(sqltypes.Text):
 class _OracleBoolean(sqltypes.Boolean):
     def get_dbapi_type(self, dbapi):
         return dbapi.NUMBER
-    
-    def result_processor(self, dialect, coltype):
-        def process(value):
-            if value is None:
-                return None
-            return value and True or False
-        return process
-
-    def bind_processor(self, dialect):
-        def process(value):
-            if value is True:
-                return 1
-            elif value is False:
-                return 0
-            elif value is None:
-                return None
-            else:
-                return value and True or False
-        return process
 
 colspecs = {
     sqltypes.Boolean : _OracleBoolean,
diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index d0a87d282..7a9e2e710 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -525,6 +525,7 @@ class PGDialect(default.DefaultDialect):
     supports_sane_rowcount = True
     
     supports_native_enum = True
+    supports_native_boolean = True
     
     supports_sequences = True
     sequences_optional = True
diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index 2b929331a..d83eb4b86 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -146,23 +146,7 @@ class TIME(_DateTimeMixin, sqltypes.Time):
     def result_processor(self, dialect, coltype):
         return self._result_processor(datetime.time)
 
-class _SLBoolean(sqltypes.Boolean):
-    def bind_processor(self, dialect):
-        def process(value):
-            if value is None:
-                return None
-            return value and 1 or 0
-        return process
-
-    def result_processor(self, dialect, coltype):
-        def process(value):
-            if value is None:
-                return None
-            return value == 1
-        return process
-
 colspecs = {
-    sqltypes.Boolean: _SLBoolean,
     sqltypes.Date: DATE,
     sqltypes.DateTime: DATETIME,
     sqltypes.Float: _SLFloat,