Bw Extraction query

Dear All,

can someone please explain this .During extraction process of Data from Ecc6.0 to BI , will the Databse size of ecc6.0 will increase ?? As far as i understood from BI consultant that there will be no changes in ECC6.0 database size , but during the extraction process it will need space in virtual memory and once the extraction process completed the virtual memory will be freed.But i noticed that the partion in which oracle database resides almost getting full,once the extraction process is started.

Regards.