Re: pg_amcheck contrib application

> On Mar 11, 2021, at 3:36 AM, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
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>> 11 марта 2021 г., в 13:12, Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> написал(а):
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>> client-side tools whose sole task is to execute server-side functionality in a slightly filtered way
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> By the way, can we teach pg_amcheck to verify database without creating local PGDATA and using bare minimum of file system quota?

pg_amcheck does not need a local data directory to check a remote database server, though it does need to connect to that server. The local file system quota should not be a problem, as pg_amcheck does not download and save any data to disk. I am uncertain if this answers your question. If you are imagining pg_amcheck running on the same server as the database cluster, then of course running pg_amcheck puts a burden on the server to read all the relation files necessary, much as running queries over the same relations would do.

> We can implement a way for a pg_amcheck to ask for some specific file, which will be downloaded by backup tool and streamed to pg_amcheck.
> E.g. pg_amcheck could have a restore_file_command = 'backup-tool bring-my-file %backup_id %file_name' and probably list_files_command='backup-tool list-files %backup_id'. And pg_amcheck could then fetch bare minimum of what is needed.
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> I see that this is somewhat orthogonal idea, but from my POV interesting one.

pg_amcheck is not designed to detect corruption directly, but rather to open one or more connections to the database and execute sql queries which employ the contrib/amcheck sql functions.

—
Mark Dilger
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