Re: Hot standby and synchronous replication status

Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> That was proposed and rejected quite a long time ago. We don't *want*
>> people to be able to "just change a GUC" and have their xlog go
>> somewhere else, because of the foot-gun potential. You need to be sure
>> that the existing WAL files get moved over when you do something like
>> that, and the GUC infrastructure isn't up to ensuring that.

> Doesn't the same argument apply to data_directory?

No. Changing data_directory might result in failure to start (if
you didn't move the actual data over there) but it's unlikely to result
in irretrievable corruption of your data. The key issue here is the
need to keep data and xlog in sync, and moving the whole data directory
doesn't create risks of that sort.

Now admittedly it's not hard to screw yourself with a careless manual
move of xlog, either. But at least the database didn't hand you a knob
that invites clueless frobbing.

regards, tom lane