Re: BUG #17735: Uninstall of one version wipes out logs for all versions

A few small typos in the original text are corrected below:

"wanted to wipe and data directory" should read "wanted to wipe *the* data
directory"
"make use log_filename" should read "make use *of* log_filename"
"should parse to postgresql.conf file" should read "should parse *the*
postgresql.conf file"

__________________
S. Bortman
n'eNow

On Mon, Jan 2, 2023 at 3:33 PM PG Bug reporting form <noreply(at)postgresql(dot)org>
wrote:

> The following bug has been logged on the website:
>
> Bug reference: 17735
> Logged by: Sam Bortman
> Email address: sam(dot)bortman(at)gmail(dot)com
> PostgreSQL version: 15.1
> Operating system: Linux (Debian-based)
> Description:
>
> Hello,
>
> The following is likely only an issue with the Devian-based distributions
> and should be passed along to the package maintainer. I have no access to
> other Linux systems to try this on. It may be a common issue, but I have
> no
> way to verify this, currently.
>
> I discovered an issue while having two versions of PostgreSQL (namely 14.x
> and 15.1) installed side-by-side on an Ubuntu-based server. There were
> absolutely no issues, or conflicts, nor were there any sort of negative
> interaction between the versions at run-time. It worked like a charm!
>
> When I issued an "sudo apt purge postgresql-14" command I was presented
> with
> the familiar prompt of whether I wanted to wipe and data directory
> associated with my PG 14 cluster. I replied in the affirmative. As
> expected /var/lib/postgresql/14 was gone. So, far so good.
>
> However, the /var/log/postgresql directory was also wiped in its entirety.
> The directory has previously hosted both postgresql-14-main.log* log files,
> as well as postgresql-15-main.log* files.
>
> Expected behavior:
> Since PG allows different versions to be installed concurrently, ideally
> only the logs which embed the version number of the product being
> uninstalled should be purged. In my case, postgresql-14-main.log* should
> have been removed, to the exclusion of all other installed versions.
>
> I realize that Debina-based installations do not make use log_filename,
> which makes it possible to infer the product version from the log filename
> (as mentioned above), whereas on other distributions it may be impossible
> to
> tell which log file was created with which version.
>
> So perhaps you want to consider excluding all log files from deletion when
> such version-determination is impossible. Or perhaps the uninstallation
> script on such distributions should parse to postgresql.conf file to
> determine the value of log_filename is so that it knows what pattern to
> delete. Nothing is fool-proof, but perhaps this is better than nothing?)
>
>