add metadata column

odbc/table_code_odbc.go

@@ -88,20 +88,25 @@ func tableODBC(ctx context.Context, connection *plugin.Connection) (*plugin.Tabl
 		return nil, err
 	}
 
-	// Assume all columns can be used as key columns (qualifiers)
-	keyColumns := getKeyColumns(cols)
+	// Add the _metadata column to the list of columns
+	cols = append(cols, &plugin.Column{
+		Name:        "_metadata",
+		Type:        proto.ColumnType_JSON,
+		Transform:   transform.FromField("_metadata"),
+		Description: "Metadata related to the data source",
+	})
 
 	return &plugin.Table{
 		Name:        strings.ToLower(dsn) + "_" + tablename,
 		Description: dsn + ":" + tablename,
 		List: &plugin.ListConfig{
-			Hydrate:    listODBC,
-			KeyColumns: keyColumns,
+			Hydrate: listODBC,
 		},
 		Columns: cols,
 	}, nil
 }
 
+
 // Define a function to get key columns from the list of columns
 func getKeyColumns(columns []*plugin.Column) plugin.KeyColumnSlice {
 	var keyCols plugin.KeyColumnSlice
@@ -195,6 +200,12 @@ func fetchFromDatabase(ctx context.Context, dsn string, tablename string, quals
 		}
 
 		m := make(map[string]interface{})
+
+		m["_metadata"] = map[string]interface{}{
+			"connection_name": "odbc",
+			"dsn":             dsn,
+		}
+
 		for i, colName := range columns {
 			val := colPtrs[i].(*interface{})
 			m[helpers.EscapePropertyName(colName)] = *val