[azurelake]

Just FYI if you didn’t already know this:

  Any transaction which is run at a transaction isolation   level other than SERIALIZABLE will not be affected by SSI. If you want to enforce business rules through SSI, all transactions should be run at the SERIALIZABLE transaction isolation level, and that should probably be set as the default.

Given that running everything at SERIALIZABLE probably isn’t practical for you, I think it’s more clear code wise to use explicit locks. That way, you can grep for what queries are related synchronization wise, vs. SERIALIZABLE being implicit.

[wongarsu]

Continuing with the FYIs:

Explicit locks can mean just calling LOCK TABLE account_balances IN SHARE ROW EXCLUSIVE MODE; early in the transaction and then doing SELECT ... FOR UPDATE; or similar configurations to enforce business rules where it matters.

https://www.postgresql.org/docs/current/sql-lock.html