Larger instances with effective_cache_size configured don't support --offload for serverless exports

[Jeroen Visser]

When creating an export using `--offload`, for serverless exports, on an instance that has `effective_cache_size` set to the maximum allowed for the instance size, an error occurs with reason `invalidFlagValue`. When removing the flag, the export can be started.

Is this expected behaviour? Is there a way to avoid this flag being applied to the temporary serverless instance?

[Elliott (Google Cloud Platform Support)]

Hello Jeroen,

I understand that for larger Cloud SQL instances with effective_cache_size set to the maximum results in an error, “invalidFlagValue” when trying to perform a Serverless Export.

The Serverless exports feature lets you export data from your MySQL or PostgreSQL database instances without affecting performance or risk to your production workloads.

I noticed that you have opened a public issue tracker for this and the analyst was able to reproduce the error when trying to perform a serverless export with the effective_cache_size flag set to 4500000.

From that Issue Tracker for the benefit of the community, I am posting your steps here:

1- Create a Postgres instance with effective_cache_size configured to the maximum allowed for a given instance size (8vCPUs, 52GiB, configured to 4500000, but larger instance and same size also triggers this issue).

2- Attempt to start serverless export (SQL, single DB, to GCS bucket in same region).

3- Observe described error

4- Remove flag value

5- Repeat step 2

6- Confirm that export works without flag

Other information (workarounds you have tried, documentation consulted, etc):

Removing effective_cache_size flag works.

Non-serverless exports work regardless of flag config.

She advised that the Cloud SQL Specialists are aware of this issue and are working towards a resolution but there is no ETA right now but you may follow the progress here.

We apologize for the inconvenience and thank you for reporting it.

Thank you.