Re: Trying to break online checksums with LLMs

On 9/10/26 22:37, Tom Lane wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> But much more seriously, Claude also noticed this: In general, if
>> PostgreSQL creates a relation and then crashes before commit, the
>> relation files are left on disk and not removed, but there's no
>> catalog entry pointing to them any more. If checksums are enabled
>> using pg_checksums, such files are updated to have checksums as well.
>> But this feature enables checksums by working through the catalog, so
>> it won't update those files. That means that if, at any point in the
>> history of the cluster, there's ever been a crash that left a relation
>> file behind on disk, and then you use this feature to enable
>> checksums, and then after that you take a base backup, checksum
>> verification will fail, and thus the backup will fail. I don't quite
>> see how we can actually fix this, and it seems like a serious problem.
> Don't we have logic somewhere to clean up orphaned relation files?
>
> regards, tom lane
>
There is an item [1] on the TODO list, and a thread [2]:

[1] https://wiki.postgresql.org/wiki/Todo#Administration

[2]
https://www.postgresql.org/message-id/flat/200606081508.k58F85m29270%40candle.pha.pa.us