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Subject: Re: BUG #17212: pg_amcheck fails on checking temporary relations
From: Mark Dilger <mark.dilger@enterprisedb.com>
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Date: Wed, 6 Oct 2021 10:19:01 -0700
Cc: Pavel Borisov <pashkin.elfe@gmail.com>,
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To: Peter Geoghegan <pg@bowt.ie>
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> On Oct 6, 2021, at 10:16 AM, Peter Geoghegan <pg@bowt.ie> wrote:
>=20
> 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=3D"no_such_index"
	pg_amcheck --table=3D"somebody_elses_temp_table"
	pg_amcheck --index=3D"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.


=E2=80=94
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company