How to effectively stream data from DC into cloud migration platform?

Hi,

as a vendor, we have to migrate a huge dataset from our app from Jira DC into the cloud. I noticed that my approach is too slow and memory consuming. I require a data pipeline, that reads values from custom fields in Jira issues and pumps that data into the migration platform. Is there any example how to effectively do this with least runtime and memory consume?
I came up to build a CSV and stream through the issues, but I cannot come up with a way in Java to stream the issues directly into the output stream. I only know apache beam, but is there already an existing solution in Java or Jira DC?

Hello,

To clarify you are using migration APIs to export your custom field values but it is taking too much memory?
You could try chunking your app data smaller to avoid having to read too much in memory but slowness may still be an issue, how large is your dataset?