MIME-Version: 1.0
References: <20260324151133.7940a5c1f2ebd594d54da481@sraoss.co.jp>
 <CAA5RZ0snnePNW1NKGKh+NyJ1CY26T5F_6-tTq+BHWM2kj1fN1g@mail.gmail.com>
 <20260325012847.e026ba1860c07288efe3e97d@sraoss.co.jp>
 <20260326192203.e6dbb8d80f8d27dc15ceee59@sraoss.co.jp>
 <acW8MW-Gb8Aj_TH2@paquier.xyz>
 <20260327163549.b5df519c0099970ddbb3412d@sraoss.co.jp>
 <CAA5RZ0tNh03LLgJVMA=PXSdY8YVoui4_GyfbfTrYK5cka3Q9Rw@mail.gmail.com>
 <20260328161802.f35b5a3e739566ffd7c1053b@sraoss.co.jp>
 <20260413170551.5ec43ba5a2c848f0d46c6a0b@sraoss.co.jp>
 <CAA5RZ0tUHU-r=Tc47P2DZyytF7x5h5OwBiRABe_dZt+zWNqe9g@mail.gmail.com>
 <20260427203207.32aa6ca37f2a18a05508dfda@sraoss.co.jp>
 <CAA5RZ0vwgXZ5kF2GvYBR+Ma1LPSbDjE9pjANzSiUw3wmpv51PQ@mail.gmail.com>
In-Reply-To: 
 <CAA5RZ0vwgXZ5kF2GvYBR+Ma1LPSbDjE9pjANzSiUw3wmpv51PQ@mail.gmail.com>
From: Zsolt Parragi <zsolt.parragi@percona.com>
Date: Thu, 14 May 2026 22:46:47 +0100
Message-ID: 
 <CAN4CZFO5BAr2uP=2CDDyX5ydFw8Ku=wtJ0ZtfLTKuWvXH6J2yQ@mail.gmail.com>
Subject: Re: Track skipped tables during autovacuum and autoanalyze
To: Sami Imseih <samimseih@gmail.com>
Cc: Yugo Nagata <nagata@sraoss.co.jp>, Michael Paquier <michael@paquier.xyz>,
	Pgsql Hackers <pgsql-hackers@postgresql.org>
Content-Type: multipart/mixed; boundary="00000000000036b9af0651ce0902"
Archived-At: 
 <https://www.postgresql.org/message-id/CAN4CZFO5BAr2uP%3D2CDDyX5ydFw8Ku%3DwtJ0ZtfLTKuWvXH6J2yQ%40mail.gmail.com>
Precedence: bulk

--00000000000036b9af0651ce0902
Content-Type: text/plain; charset="UTF-8"

Hello!

+ TimestampTz last_skipped_vacuum_time; /* user initiated vacuum */
+ PgStat_Counter skipped_vacuum_count;
+ TimestampTz last_skipped_autovacuum_time; /* autovacuum initiated */
+ PgStat_Counter skipped_autovacuum_count;
+ TimestampTz last_skipped_analyze_time; /* user initiated */
+ PgStat_Counter skipped_analyze_count;
+ TimestampTz last_skipped_autoanalyze_time; /* autovacuum initiated */
+ PgStat_Counter skipped_autoanalyze_count;
+

Doesn't these also require a PGSTAT_FILE_FORMAT_ID change?


There's also an asymmetric case for the skipped counters, is that intentional?

| Command                                 | `skipped_vacuum_count` |
`skipped_analyze_count` |
|-----------------------------------------|------------------------|-------------------------|
| `VACUUM (FULL, ANALYZE, SKIP_LOCKED) t` | 0                      | 1
                      |
| `VACUUM (ANALYZE, SKIP_LOCKED) t`       | 1                      | 1
                      |
| `VACUUM (FULL, SKIP_LOCKED) t`          | 0                      | 0
                      |


> Initially, I was concerned that something might go wrong if a concurrent
> session performed DROP TABLE or ALTER TABLE RENAME between RangeVarGetRelidExtended()
> and RangeVarGetRelid(), but I could not find any actual issue. Even when the table
> name is changed, the correct statistics entry is updated correctly.

A DROP TABLE can cause a missed skip in statistics, which is
reproducible with a custom injection point and tap test, see the
attached patch. The race window is quite minimal, but it exists.

--00000000000036b9af0651ce0902
Content-Type: application/octet-stream;
	name="0001-DROP-TABLE-race-in-expand_vacuum_rel-skip-lock-path.patch.nocfbot"
Content-Disposition: attachment;
	filename="0001-DROP-TABLE-race-in-expand_vacuum_rel-skip-lock-path.patch.nocfbot"
Content-Transfer-Encoding: base64
Content-ID: <f_mp60pwie0>
X-Attachment-Id: f_mp60pwie0
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=
--00000000000036b9af0651ce0902--