Azure application insights workspace based migration related questions

Hello,

We have migrated our classic application insights instances to workspace based successfully.

After migration, I see that new data post migration is getting stored in linked log analytics workspace (which is expected) and also new data is getting stored at classic application insights as well.

As per your documentation, after migration, old data will remain in classic application insight and new data will be stored in linked log analytics workspace.

https://learn.microsoft.com/en-us/azure/azure-monitor/app/convert-classic-resource

Questions

• Why new data is still getting stored in old classic app insights after migration? This is not mentioned in https://learn.microsoft.com/en-us/azure/azure-monitor/app/convert-classic-resource.
  • Let us assume that it is getting stored to support the backward compatibility. How many days this is supported after migration?
• We have existing powerbi reports which are pulling data from classic application insights. After migration, let us suppose if I want some data from old app insights and some from new app insights, in this case, I have to write two separate queries and combine the results. Is my understanding correct?