assertRequest(!isNullOrEmpty(query), "SQL query is empty");
assertRequest(!isNullOrEmpty(user), "User (%s) is empty", PRESTO_USER);
assertRequest(!isNullOrEmpty(catalog), "Catalog (%s) is empty", PRESTO_CATALOG);
assertRequest(!isNullOrEmpty(schema), "Schema (%s) is empty", PRESTO_SCHEMA);
ClientSession session = new ClientSession(serverUri(), user, source, catalog, schema, false);
StatementClient client = new StatementClient(httpClient, queryResultsCodec, session, query);
List<Column> columns = getColumns(client);
Iterator<List<Object>> iterator = flatten(new ResultsPageIterator(client));