The VMware Tanzu Greenplum streaming server (GPSS) is an ETL (extract, transform, load) tool. An instance of the GPSS server ingests streaming data from one or more clients, using Tanzu Greenplum Database readable external tables to transform and insert the data into a target Tanzu Greenplum table. The data source and the format of the data are specific to the client. You may also unload data from Tanzu Greenplum Database to a file using writable external tables.