Re: BUG #17212: pg_amcheck fails on checking temporary relations

[Mark Dilger]

> On Oct 6, 2021, at 10:16 AM, Peter Geoghegan <p...@bowt.ie> wrote:
> 
> A return value of 0 cannot be said to indicate that the database is
> not corrupt;

Nor can a non-zero value be said to indicate that the database is corrupt.

These invocations will still return a non-zero exit status:

        pg_amcheck -D no_privs_database
        pg_amcheck --index="no_such_index"
        pg_amcheck --table="somebody_elses_temp_table"
        pg_amcheck --index="somebody_elses_temp_index"

but these have been modified to no longer do so:

        pg_amcheck -D my_database_in_recovery --parent-check
        pg_amcheck -D my_database_in_recovery --heapallindexed
        pg_amcheck --all

Please compare to:

        find /private || echo "FAIL"
        rm /not/my/file || echo "FAIL"

I'm not sure how the idea that pg_amcheck should never give back a failure code 
unless there is corruption got inserted into this thread, but I'm not on board 
with that as an invariant statement.  The differences in the upcoming version 
are

1) --all no longer means "all relations" but rather "all checkable relations"
2) checking options should be automatically downgraded under circumstances 
where they cannot be applied
3) unlogged relations during replication are by definition not corrupt

I think #1 and #3 are unsurprising enough that they need no documentation 
update.  #2 is slightly surprising (at least to me) so I updated the docs for 
it.


—
Mark Dilger
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