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Subject: Re: [PATCH] Improve amcheck to also check UNIQUE constraint in btree
 index.
From: Mark Dilger <mark.dilger@enterprisedb.com>
In-Reply-To: <CAH2-Wz=-XLP3NUFnJwtBXF-ZWESoqpJ3z+n29V7LsCLgYgVHKA@mail.gmail.com>
Date: Fri, 17 May 2024 13:10:46 -0700
Cc: Pavel Borisov <pashkin.elfe@gmail.com>,
 Alexander Korotkov <aekorotkov@gmail.com>,
 Tom Lane <tgl@sss.pgh.pa.us>,
 Noah Misch <noah@leadboat.com>,
 Peter Eisentraut <peter@eisentraut.org>,
 Aleksander Alekseev <aleksander@timescale.com>,
 Postgres hackers <pgsql-hackers@lists.postgresql.org>,
 Maxim Orlov <orlovmg@gmail.com>,
 Andres Freund <andres@anarazel.de>,
 Greg Stark <stark@mit.edu>,
 Julien Rouhaud <rjuju123@gmail.com>,
 David Steele <david@pgmasters.net>,
 Maxim Orlov <m.orlov@postgrespro.ru>,
 lubennikovaav@gmail.com
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To: Peter Geoghegan <pg@bowt.ie>
Archived-At: <https://www.postgresql.org/message-id/4BBFF6D5-58EE-40B3-A770-9BA2F46A1C69%40enterprisedb.com>
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> On May 17, 2024, at 1:00 PM, Peter Geoghegan <pg@bowt.ie> wrote:
>=20
> Many different parts of the B-Tree code will fight against allowing
> duplicates of the same value to span multiple leaf pages -- this is
> especially true for unique indexes.=20

The quick-and-dirty TAP test I wrote this morning is intended to =
introduce duplicates across page boundaries, not to test for ones that =
got there by normal database activity.  In other words, the TAP test =
forcibly corrupts the index by changing a value on one side of a =
boundary to be equal to the value on the other side of the boundary.  =
Prior to the corrupting action the values were all unique.

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