presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/metadata/DatabaseMetadataModule.java/DatabaseMetadataModule/configure
class DatabaseMetadataModule:        @Override
        public void configure(Binder binder)
        {
            configBinder(binder).bindConfig(JdbcDatabaseConfig.class);
            configBinder(binder).bindConfig(MySqlDataSourceConfig.class, ForMetadata.class, "metadata");
            configBinder(binder).bindConfigDefaults(MySqlDataSourceConfig.class, ForMetadata.class, config -> {
                config.setMaxConnections(100);
                config.setDefaultFetchSize(1000);
            });
        }