Isolation level?

[andrew222651]

What isolation level does the application use for Postgres transactions?

[abelanger5]

We use the default isolation level (read committed), instead favoring FOR UPDATE and advisory locks for concurrency control where necessary. We experimented with SERIALIZABLE early on, but it caused us too much overhead and performance issues.

[andrew222651]

Interesting... I thought SERIALIZABLE was supposed to have low overhead

[abelanger5]

I no longer have concrete data on the performance, but here's the PR from the time: #535

We would often be retrying 2-3 times per assignment under heavy load, which would add corresponding DB pressure. The entire architecture has changed quite a bit since then to avoid situations where this would even be necessary.