Make adding idempotent and add to relations.

Author: marianogappa

schema/table.go

@@ -130,7 +130,12 @@ func AddCqIDs(table *Table) {
 // AddCqClientID adds the cq_client_id column to the table,
 // which is used to identify the multiplexed client that fetched the resource
 func AddCqClientID(t *Table) {
-	t.Columns = append(ColumnList{CqClientIDColumn}, t.Columns...)
+	if t.Columns.Get(CqClientIDColumn.Name) == nil {
+		t.Columns = append(ColumnList{CqClientIDColumn}, t.Columns...)
+	}
+	for _, rel := range t.Relations {
+		AddCqClientID(rel)
+	}
 }
 
 // CqIDAsPK sets the cq_id column as primary key if it exists