fix failing pg tests

Author: vvkh

data_diff/databases/postgresql.py

@@ -190,21 +190,23 @@ def select_table_schema(self, path: DbPath) -> str:
         if database:
             info_schema_path.insert(0, database)
 
-        return f"""
-            SELECT column_name, data_type, datetime_precision,
-                CASE
-                    WHEN data_type = 'numeric'
-                        THEN coalesce(numeric_precision, 131072 + 16383)
-                    ELSE numeric_precision
-                END AS numeric_precision,
-                CASE
-                    WHEN data_type = 'numeric'
-                        THEN coalesce(numeric_scale, 16383)
-                    ELSE numeric_scale
-                END AS numeric_scale
-                FROM {'.'.join(info_schema_path)}
-            WHERE table_name = '{table}' AND table_schema = '{schema}'
+        return (
+            f"""SELECT column_name, data_type, datetime_precision,
+                    -- see comment for DEFAULT_NUMERIC_PRECISION
+                    CASE
+                        WHEN data_type = 'numeric'
+                            THEN coalesce(numeric_precision, 131072 + {self.dialect.DEFAULT_NUMERIC_PRECISION})
+                        ELSE numeric_precision
+                    END AS numeric_precision,
+                    CASE
+                        WHEN data_type = 'numeric'
+                            THEN coalesce(numeric_scale, {self.dialect.DEFAULT_NUMERIC_PRECISION})
+                        ELSE numeric_scale
+                    END AS numeric_scale
+                    FROM {'.'.join(info_schema_path)}
+                    WHERE table_name = '{table}' AND table_schema = '{schema}'
             """
+        )
 
     def select_table_unique_columns(self, path: DbPath) -> str:
         database, schema, table = self._normalize_table_path(path)