Get started with VACUUM #407
Description
VACUUM is a SQLite-specific operation that squeezes deleted space out of database files. It's interesting for two reasons. First, it makes the files consume less disk space; second, it overwrites the deleted space so that it cannot be forensically analyzed by an attacker to recover some or all of the data that was deleted.
VACUUM is not an operation that should be performed whenever anything is deleted from the database: that would be too expensive. However, it should be performed on a reasonably frequent basis to protect the user's privacy and disk space.
Write some code to perform the VACUUM operation periodically, noting that it should not take place while the database is being used for anything else.
Suggestions: One good time to perform a VACUUM operation might be during a Graceful Shutdown (put card number in here). However, it will still be possible for the Node to crash unexpectedly, in which case the database file will be unVACUUMed. Therefore, it might be advisable to VACUUM during bootstrap as well.