Great question. So the issue that triggered this was a bug caused by an unrepeatable read. We changed the global level and it solved the problem. However, to s

Great question. So the issue that triggered this was a bug caused by an unrepeatable read. We changed the global level and it solved the problem. However, to stop this from affecting performance too much we targeted this isolation change to only the transaction in question. We've also rarely touched it; it was the first time we actually messed with isolation. For the 1-5% of times, we figured it would be useful to know.