Re: pg_upgrade should truncate/remove its logs before running

On Thu, Dec 16, 2021 at 12:23:08PM +0100, Daniel Gustafsson wrote:
> > On 16 Dec 2021, at 12:11, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> wrote:
>
> > Could we make it write just one log file? Is having multiple log files better?
>
> Having individual <checkname>.txt files from checks with additional information
> on how to handle the error are quite convenient when writing wrappers around
> pg_upgrade (speaking from experience of having written multiple pg_upgraade
> frontends). Parsing a single logfile is more work, and will break existing
> scripts.
>
> I'm in favor of a predictable by default logpath, with a parameter to override,
> as mentioned upthread.

I put this together in the simplest way, prefixing all the filenames with the
configured path..

Another options is to chdir() into the given path. But, pg_upgrade takes (and
requires) a bunch of other paths, like -d -D -b -B, and those are traditionally
interpretted relative to CWD. I could getcwd() and prefix all the -[dDbB] with
that, but prefixing a handful of binary/data paths is hardly better than
prefixing a handful of dump/logfile paths. I suppose that openat() isn't
portable. I don't think this it's worth prohibiting relative paths, so I can't
think of any less-naive way to do this.

I didn't move the delete-old-cluster.sh, since that's intended to stay around
even after a successful upgrade, as opposed to the other logs, which are
typically removed at that point.

--
Justin