Added Database.SUPPORTS_UNIQUE_CONSTAINT

Author: erezsh

data_diff/databases/base.py

@@ -110,6 +110,7 @@ class Database(AbstractDatabase):
     default_schema: str = None
     SUPPORTS_ALPHANUMS = True
     SUPPORTS_PRIMARY_KEY = False
+    SUPPORTS_UNIQUE_CONSTAINT = False
 
     _interactive = False
 
@@ -245,6 +246,8 @@ def select_table_unique_columns(self, path: DbPath) -> str:
         )
 
     def query_table_unique_columns(self, path: DbPath) -> List[str]:
+        if not self.SUPPORTS_UNIQUE_CONSTAINT:
+            raise NotImplementedError("This database doesn't support 'unique' constraints")
         res = self.query(self.select_table_unique_columns(path), List[str])
         return list(res)
 

data_diff/databases/mysql.py

@@ -40,6 +40,7 @@ class MySQL(ThreadedDatabase):
     ROUNDS_ON_PREC_LOSS = True
     SUPPORTS_ALPHANUMS = False
     SUPPORTS_PRIMARY_KEY = True
+    SUPPORTS_UNIQUE_CONSTAINT = True
 
     def __init__(self, *, thread_count, **kw):
         self._args = kw

data_diff/databases/oracle.py

@@ -40,6 +40,7 @@ class Oracle(ThreadedDatabase):
     }
     ROUNDS_ON_PREC_LOSS = True
     SUPPORTS_PRIMARY_KEY = True
+    SUPPORTS_UNIQUE_CONSTAINT = True
 
     def __init__(self, *, host, database, thread_count, **kw):
         self.kwargs = dict(dsn=f"{host}/{database}" if database else host, **kw)

data_diff/databases/postgresql.py

@@ -47,6 +47,7 @@ class PostgreSQL(ThreadedDatabase):
     }
     ROUNDS_ON_PREC_LOSS = True
     SUPPORTS_PRIMARY_KEY = True
+    SUPPORTS_UNIQUE_CONSTAINT = True
 
     default_schema = "public"
 

data_diff/joindiff_tables.py

@@ -201,7 +201,7 @@ def _test_duplicate_keys(self, table1: TableSegment, table2: TableSegment):
 
         # Test duplicate keys
         for ts in [table1, table2]:
-            unique = ts.database.query_table_unique_columns(ts.table_path)
+            unique = ts.database.query_table_unique_columns(ts.table_path) if ts.database.SUPPORTS_UNIQUE_CONSTAINT else []
 
             t = ts.make_select()
             key_columns = ts.key_columns