Postgres export to S3

Question

I'm trying to export a snapshot to S3, but nothing actually gets exported and the export metadata file shows a PERMISSIONS_DO_NOT_EXIST skip error on every table. The docs say this is a permission error that can be resolved by granting permissions to the tables:
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ExportSnapshot.html#USER_ExportSnapshot.postgres-permissions

However, I've done just that with my master user multiple times and nothing has changed.  
  
Basically the whole export metadata file looks like this:   
  
{"perTableStatus":\[{"tableStatistics":{"extractionStartTime":"Apr 17, 2021 10:27:49 AM","partitioningInfo":{"numberOfPartitions":1,"numberOfCompletedPartitions":0}},"warningMessage":{"skippedTable":\[{"reason":"PERMISSIONS_DO_NOT_EXIST"}]},"status":"SKIPPED","sizeGB":1.8310546875E-4,"target":"mailserver.public.account"}  
  
Am I doing something wrong?  
Any help would be appreciated.

Answer

A friend has suggested that it's the permissions _at the time of backup_ that matter, so my efforts to export to S3 will remain forever fruitless. It'd be nice if the docs noted this.

Postgres export to S3

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