On Thu, Aug 22, 2019 at 08:07:53 -0700, Quanah Gibson-Mount wrote:
As you noted, overlays can intercept write operations. The problem is
when an overlay intercepts a write op, where the write op occurs in the
primary DB, but returns before accesslog is called, meaning that
accesslog does not record the write op. This then breaks consistency
between the servers. Since you're logging failures, you hit a different
case, which generally underscores why this entire processing stack needs
rewriting for 2.5.
Can that really happen between unique and accesslog overlays? The unique
overlay doesn't write any data itself, it will only reject certain writes?
The actual write to the underlying mdb database will only occur after it
passed through the entire overlay chain, or am I misunderstanding how it
works?