Cloud SQL disk size is much larger than actual database

Question

Cloud SQL reports that I've used ~4TB of SSD storage, but my database is only ~225 GB. What explains this discrepancy? Is there something I can delete to free up space? If I moved it to a different instance, would the required storage go down?

Answer 1

There are a couple of options about why your Cloud SQL storage has increase:

-Did you enable Point-in-time recovery? PITR uses write-ahead logs and if you enabled this feature, that could be the reason why of your increases.

-Have you used temporary tables and you have not deleted them?

If none of the above applies to you, I highly recommend you to open a case with GCP support team so that they take a look at your Cloud SQL instance.

On the other hand, you should open a case to decrease the disk size to a smaller one so it won’t be necessary to create a new instance and copy all the data to that new instance in addition that shrinking the disk is done at Google's end making the effort from you the lowest possible.

A maintenance window can be scheduled where Google can proceed with this task and you may want to schedule a maintenance window to minimize the impact of the downtime. For this case it is necessary to know the new disk size and when you would like to perform this operation.

Finally, if you prefer to use the migration method, you should export the DB, then create the new instance, import the DB and synchronize the old one with the new one to have all the data in both instances to which can take several hours to complete those four steps.