Re: Avoid erroring out when unable to remove or parse logical rewrite files to save checkpoint work

On 1/19/22, 11:08 AM, "Andres Freund" <andres@anarazel.de> wrote:
> On 2022-01-19 13:34:21 -0500, Tom Lane wrote:
>> As far as the patch itself goes, I agree that failure to unlink
>> is noncritical, because such a file would have no further effect
>> and we can just ignore it.
>
> I don't agree. We iterate through the directory regularly on systems with
> catalog changes + logical decoding. An ever increasing list of gunk will make
> that more and more expensive.  And I haven't heard a meaningful reason why we
> would have map-* files that we can't remove.

I think the other side of this is that we don't want checkpointing to
continually fail because of a noncritical failure.  That could also
lead to problems down the road.

> Ignoring failures like this just makes problems much harder to debug and they
> tend to bite harder for it.

If such noncritical failures happened regularly, the server logs will
likely become filled with messages about it.  Perhaps users may not
notice for a while, but I don't think the proposed patch would make
debugging excessively difficult.

Nathan