Simplify double-inheritance of Redshift dialect from Postgres dialect

All the Postgres mixins are already inherited into the Redshift dialect via its base class, so there is no need to duplicate the mixins.

Author: Sergey Vasilyev

data_diff/databases/redshift.py

@@ -11,27 +11,42 @@
     DbPath,
     TimestampTZ,
 )
-from data_diff.abcs.mixins import AbstractMixin_MD5, AbstractMixin_NormalizeValue
 from data_diff.databases.postgresql import (
     PostgreSQL,
     MD5_HEXDIGITS,
     CHECKSUM_HEXDIGITS,
     CHECKSUM_OFFSET,
     TIMESTAMP_PRECISION_POS,
     PostgresqlDialect,
-    Mixin_NormalizeValue,
-    Mixin_MD5,
 )
 
 
 @attrs.define(frozen=False)
-class Mixin_MD5(Mixin_MD5):
+class Dialect(PostgresqlDialect):
+    name = "Redshift"
+    TYPE_CLASSES: ClassVar[Dict[str, Type[ColType]]] = {
+        **PostgresqlDialect.TYPE_CLASSES,
+        "double": Float,
+        "real": Float,
+        "super": JSON,
+    }
+    SUPPORTS_INDEXES = False
+
+    def concat(self, items: List[str]) -> str:
+        joined_exprs = " || ".join(items)
+        return f"({joined_exprs})"
+
+    def is_distinct_from(self, a: str, b: str) -> str:
+        return f"({a} IS NULL != {b} IS NULL) OR ({a}!={b})"
+
+    def type_repr(self, t) -> str:
+        if isinstance(t, TimestampTZ):
+            return f"timestamptz"
+        return super().type_repr(t)
+
     def md5_as_int(self, s: str) -> str:
         return f"strtol(substring(md5({s}), {1+MD5_HEXDIGITS-CHECKSUM_HEXDIGITS}), 16)::decimal(38) - {CHECKSUM_OFFSET}"
 
-
-@attrs.define(frozen=False)
-class Mixin_NormalizeValue(Mixin_NormalizeValue):
     def normalize_timestamp(self, value: str, coltype: TemporalType) -> str:
         if coltype.rounds:
             timestamp = f"{value}::timestamp(6)"
@@ -59,30 +74,6 @@ def normalize_json(self, value: str, _coltype: JSON) -> str:
         return f"nvl2({value}, json_serialize({value}), NULL)"
 
 
-@attrs.define(frozen=False)
-class Dialect(PostgresqlDialect, Mixin_MD5, Mixin_NormalizeValue, AbstractMixin_MD5, AbstractMixin_NormalizeValue):
-    name = "Redshift"
-    TYPE_CLASSES: ClassVar[Dict[str, Type[ColType]]] = {
-        **PostgresqlDialect.TYPE_CLASSES,
-        "double": Float,
-        "real": Float,
-        "super": JSON,
-    }
-    SUPPORTS_INDEXES = False
-
-    def concat(self, items: List[str]) -> str:
-        joined_exprs = " || ".join(items)
-        return f"({joined_exprs})"
-
-    def is_distinct_from(self, a: str, b: str) -> str:
-        return f"({a} IS NULL != {b} IS NULL) OR ({a}!={b})"
-
-    def type_repr(self, t) -> str:
-        if isinstance(t, TimestampTZ):
-            return f"timestamptz"
-        return super().type_repr(t)
-
-
 @attrs.define(frozen=False, init=False, kw_only=True)
 class Redshift(PostgreSQL):
     dialect = Dialect()