Our company has a base on Greenplum with a total volume of almost 800 GB. What is the fastest way to transfer all data from Greenplum to a clean database on the SQL Server?
Well, faster in terms of data transfer would be trying to avoid ODBC / JDBC connections, if possible. If not possible, prefer JDBC (type 4) over ODBC.
It also depends on the overall scenario of your architecture, and about that, you did not provide any details by the way.
In general terms, I would try:
Unloading tables using writable external tables (https://docs.greenplum.org/6-6/admin_guide/load/topics/g-unloading-data-using-a-writable-external-table.html)
Moving files to SQL Server host, and Bulk Loading the data to target tables.
This would be my opinion of a faster way.
Migrating data from one database to another have a lot of additional considerations, about how are the source tables designed, distributed, partitioned, do you have functions/procedures, etc.