Content-Type: text/plain;
	charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\))
Subject: Re: BUG #17212: pg_amcheck fails on checking temporary relations
From: Mark Dilger <mark.dilger@enterprisedb.com>
In-Reply-To: 
 <CAH2-Wzkt-umhXfR1nqy=ZDXMfoN3LDK4W5VtchfWyRAuPWxtnA@mail.gmail.com>
Date: Mon, 11 Oct 2021 10:46:16 -0700
Cc: Robert Haas <robertmhaas@gmail.com>,
 Pavel Borisov <pashkin.elfe@gmail.com>,
 Alexander Lakhin <exclusion@gmail.com>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
Content-Transfer-Encoding: quoted-printable
Message-Id: <40DB088B-C96F-49B2-BC84-BDC8D35C7E97@enterprisedb.com>
References: <17212-34dd4a1d6bba98bf@postgresql.org>
 <CAH2-Wz=bw-Uk2yoOq7yevC9hyMGgZ2Ud34nd9YJJPXJ3pkVcrw@mail.gmail.com>
 <E85855BD-C063-4B24-9EAA-02DECC8F42B9@enterprisedb.com>
 <E283B45F-5745-49C9-BBC7-99876E2FABD1@enterprisedb.com>
 <f42de8ec-f219-0922-93b3-37a72bba1feb@gmail.com>
 <28B36E41-1E8F-4DC1-A924-711621BA4972@enterprisedb.com>
 <CAH2-Wz=v4py=c79J7wpdVmQMkd8rO7gj5Ur5Dp4E0y7aQUz6cg@mail.gmail.com>
 <386F66EE-DEFD-42EA-9DB2-102BF3414669@enterprisedb.com>
 <CAH2-Wzkwb+1GSONMrXByHhgkzD-N59A_kFcvsoA_+M9cNNHm5g@mail.gmail.com>
 <CA+TgmobJnZE6WMw1y+N9ts36nsbL_un0CYB_khieg8rOa86RBw@mail.gmail.com>
 <CAH2-Wzm02e=jAarpzeZGyK8JyXTvuHCfJ9KC5svosD72nROKrw@mail.gmail.com>
 <B2BDB87C-8288-436E-B3DC-8AEB92FEB8F1@enterprisedb.com>
 <CAH2-Wz=WYdmbc1k8Lr2P4eQeYkh1UYvyDigzrvukejcWc2jKOA@mail.gmail.com>
 <c422a1aa-81c0-0762-0971-9a026cf2aa79@gmail.com>
 <CAH2-WzndLb0-GZcshTJGw6u6SQrJ5puyFiFYh-DWR8ue2zQuvA@mail.gmail.com>
 <CALT9ZEGhuXiH54VgyVJ65V+ccGqPqHTduBM4saPWSD2mrD5C6Q@mail.gmail.com>
 <F824CD5F-C82F-451C-AE67-9AD31447424A@enterprisedb.com>
 <CAH2-WznaYWowxxFaGK6Hv=SUQYS2-r7dQZJFWyDT_W6GGtuCjA@mail.gmail.com>
 <63FF68F5-683D-423E-A667-9C00441101A5@enterprisedb.com>
 <CAH2-Wz=8RP6izkLF=P_bFUK-CyTsO09hQ1-ZsC9P4Qiz3CughQ@mail.gmail.com>
 <561CE3DB-5CBC-44BF-9A3E-1D7FAEB123E0@enterprisedb.com>
 <CA+TgmobtAq9sNa0Z4QNx0xiP4NAobuGOnOirTWdJajkTRFvXNw@mail.gmail.com>
 <CAH2-WzmJkVKFSqJd2_uy07jPg-LW0yCHh0fgA8rFkdyk6FZOnQ@mail.gmail.com>
 <CA+TgmoYa5exExaONEnGBWRdi7A3=FKuKzewY8DXTj6+045wiFQ@mail.gmail.com>
 <CAH2-WzkwRUayddmb3uxCadV_y--DHfY+UMmjtOokiAO2xNh5fA@mail.gmail.com>
 <CA+Tgmoat1M4MAqUQM1H+bkWR=wXmi33bB0YRR=xaFk9ADs5Jeg@mail.gmail.com>
 <CAH2-Wzk3NzXYXsUKWBFuBm6aiXTh-_L2Dm9wPqfFenUvG+VbRw@mail.gmail.com>
 <543F3BF3-EDED-4C52-AF05-623921B6C409@enterprisedb.com>
 <CAH2-WzkXphRHgbaUXqMgb7SBmc_VbwdyWGYqphV6KbOH7stfxA@mail.gmail.com>
 <55A2BFE7-AAAF-4A64-BD3A-5C98EA982267@enterprisedb.com>
 <CAH2-WzniogVqNuWzNVLOKjkd8FBcSry29hN9=wiROUPw92fmGg@mail.gmail.com>
 <07159C9A-40DA-47BF-B2F4-203F5AC00890@enterprisedb.com>
 <CAH2-Wzkt-umhXfR1nqy=ZDXMfoN3LDK4W5VtchfWyRAuPWxtnA@mail.gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Archived-At: 
 <https://www.postgresql.org/message-id/40DB088B-C96F-49B2-BC84-BDC8D35C7E97%40enterprisedb.com>
Precedence: bulk


> On Oct 11, 2021, at 10:10 AM, Peter Geoghegan <pg@bowt.ie> wrote:
>=20
> This mostly looks good to me. Just one thing occurs to me: I suspect
> that we don't need to call pg_is_in_recovery() from SQL at all. What's
> wrong with just letting verify_heapam() (the C function from amcheck
> proper) show those notice messages where appropriate?

I thought a big part of the debate upthread was over exactly this point, =
that pg_amcheck should not attempt to check (a) temporary relations, (b) =
indexes that are invalid or unready, and (c) unlogged relations during =
recovery.

> In general I don't like the idea of making the behavior of pg_amcheck
> conditioned on the state of the system (e.g., whether we're in
> recovery) -- we should just let amcheck throw "invalid option" type
> errors when that's the logical outcome (e.g., when --parent-check is
> used on a replica). To me this seems rather different than not
> checking temporary tables, because that's something that inherently
> won't work. (Also, I consider the index-is-being-built stuff to be
> very similar to the temp table stuff -- same basic situation.)

I don't like having pg_amcheck parse the error message that comes back =
from amcheck.  If amcheck throws an error, pg_amcheck considers that a =
failure and ultimately exists with a non-zero status.  So, if we're =
going to have amcheck handle these cases, it will have to be with a =
NOTICE (or perhaps a WARNING) rather than an error.  That's not what =
happens now, but if you'd rather we fixed this problem that way, I can =
go do that, or perhaps as the author of the bt_*_check functions, you =
can do that and I can just do the pg_amcheck changes.

How shall we proceed?

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