feat: create an instance of the dialect instead of class object

Author: pik94

data_diff/databases/base.py

@@ -906,13 +906,16 @@ class Database(abc.ABC):
     Instanciated using :meth:`~data_diff.connect`
     """
 
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = BaseDialect
+
     SUPPORTS_ALPHANUMS: ClassVar[bool] = True
     SUPPORTS_UNIQUE_CONSTAINT: ClassVar[bool] = False
     CONNECT_URI_KWPARAMS: ClassVar[List[str]] = []
 
     default_schema: Optional[str] = None
     _interactive: bool = False
     is_closed: bool = False
+    _dialect: BaseDialect = None
 
     @property
     def name(self):
@@ -1141,10 +1144,13 @@ def close(self):
         return super().close()
 
     @property
-    @abstractmethod
     def dialect(self) -> BaseDialect:
         "The dialect of the database. Used internally by Database, and also available publicly."
 
+        if not self._dialect:
+            self._dialect = self.DIALECT_CLASS()
+        return self._dialect
+
     @property
     @abstractmethod
     def CONNECT_URI_HELP(self) -> str:

data_diff/databases/bigquery.py

@@ -1,5 +1,5 @@
 import re
-from typing import Any, List, Union
+from typing import Any, ClassVar, List, Union, Type
 
 import attrs
 
@@ -182,9 +182,9 @@ def normalize_struct(self, value: str, _coltype: Struct) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class BigQuery(Database):
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     CONNECT_URI_HELP = "bigquery://<project>/<dataset>"
     CONNECT_URI_PARAMS = ["dataset"]
-    dialect = Dialect()
 
     project: str
     dataset: str

data_diff/databases/clickhouse.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Optional, Type
+from typing import Any, ClassVar, Dict, Optional, Type
 
 import attrs
 
@@ -167,7 +167,7 @@ def normalize_timestamp(self, value: str, coltype: TemporalType) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class Clickhouse(ThreadedDatabase):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     CONNECT_URI_HELP = "clickhouse://<user>:<password>@<host>/<database>"
     CONNECT_URI_PARAMS = ["database?"]
 

data_diff/databases/databricks.py

@@ -1,5 +1,5 @@
 import math
-from typing import Any, Dict, Sequence
+from typing import Any, ClassVar, Dict, Sequence, Type
 import logging
 
 import attrs
@@ -107,7 +107,7 @@ def normalize_boolean(self, value: str, _coltype: Boolean) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class Databricks(ThreadedDatabase):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     CONNECT_URI_HELP = "databricks://:<access_token>@<server_hostname>/<http_path>"
     CONNECT_URI_PARAMS = ["catalog", "schema"]
 

data_diff/databases/duckdb.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Union
+from typing import Any, ClassVar, Dict, Union, Type
 
 import attrs
 
@@ -119,7 +119,7 @@ def normalize_boolean(self, value: str, _coltype: Boolean) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class DuckDB(Database):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     SUPPORTS_UNIQUE_CONSTAINT = False  # Temporary, until we implement it
     CONNECT_URI_HELP = "duckdb://<dbname>@<filepath>"
     CONNECT_URI_PARAMS = ["database", "dbpath"]

data_diff/databases/mssql.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, Optional
+from typing import Any, ClassVar, Dict, Optional, Type
 
 import attrs
 
@@ -157,7 +157,7 @@ def to_md5(self, s: str) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class MsSQL(ThreadedDatabase):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     CONNECT_URI_HELP = "mssql://<user>:<password>@<host>/<database>/<schema>"
     CONNECT_URI_PARAMS = ["database", "schema"]
 

data_diff/databases/mysql.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict
+from typing import Any, ClassVar, Dict, Type
 
 import attrs
 
@@ -120,7 +120,7 @@ def normalize_uuid(self, value: str, coltype: ColType_UUID) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class MySQL(ThreadedDatabase):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     SUPPORTS_ALPHANUMS = False
     SUPPORTS_UNIQUE_CONSTAINT = True
     CONNECT_URI_HELP = "mysql://<user>:<password>@<host>/<database>"

data_diff/databases/oracle.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Optional
+from typing import Any, ClassVar, Dict, List, Optional, Type
 
 import attrs
 
@@ -164,7 +164,7 @@ def normalize_number(self, value: str, coltype: FractionalType) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class Oracle(ThreadedDatabase):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     CONNECT_URI_HELP = "oracle://<user>:<password>@<host>/<database>"
     CONNECT_URI_PARAMS = ["database?"]
 

data_diff/databases/postgresql.py

@@ -122,7 +122,7 @@ def normalize_json(self, value: str, _coltype: JSON) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class PostgreSQL(ThreadedDatabase):
-    dialect = PostgresqlDialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = PostgresqlDialect
     SUPPORTS_UNIQUE_CONSTAINT = True
     CONNECT_URI_HELP = "postgresql://<user>:<password>@<host>/<database>"
     CONNECT_URI_PARAMS = ["database?"]

data_diff/databases/presto.py

@@ -1,6 +1,6 @@
 from functools import partial
 import re
-from typing import Any
+from typing import Any, ClassVar, Type
 
 import attrs
 
@@ -153,7 +153,7 @@ def normalize_boolean(self, value: str, _coltype: Boolean) -> str:
 
 @attrs.define(frozen=False, init=False, kw_only=True)
 class Presto(Database):
-    dialect = Dialect()
+    DIALECT_CLASS: ClassVar[Type[BaseDialect]] = Dialect
     CONNECT_URI_HELP = "presto://<user>@<host>/<catalog>/<schema>"
     CONNECT_URI_PARAMS = ["catalog", "schema"]