Set default transaction level to uncommitted
Set default transaction level to uncommitted

Sacrifice a bit of transaction ordering for many less deadlocks.
As the work load is mostly append-only (updates are extremely
infrequent) this does not have any significant issues in data
consistency.

owenchen93/github-mirror,gousiosg/github-mirror,jeffmcaffer/github-mirror,pombredanne/github-mirror,jeffmcaffer/github-mirror,gousiosg/github-mirror,pombredanne/github-mirror