ETL Purging on a large DB

Hello,

I am trying to understand the ETL Purging process in order so that we know it is ok to start on a large database.
We have recently realised the purge process was not enabled, therefore not working (missing value in the ETL Service Starter option).
The issue is that the database is now over 400 GB, so the first purge is expected to cover a large amount of data.
We want to determine how the purging will affect the DB, which although it is set to purge out of operational hours, whether there is a risk it could carry over to opening hours.
Is there an indication to how much data is set to purge prior to the process?
The etl assistant has a variation of purging rules, with the highest being 2 years at quarter and year, and minute level ones being 3 months. We think there will be 3/4 years of data needing purging…

Thanks.

I would do it little by little - do it in 3 month chunks.

I think that even doing it by small time periods will have a huge impact as it will read ALL records to find out those oldies you want to delete.
I would talk to a DB guy (oracle? Informix? Mssql?..) to see how to maybe run an indexation and attack it in that way…hard work indeed