Message-ID: <9be9ee9b-b816-4ff9-a929-d830e21b94fc@uni-muenster.de>
Date: Sat, 25 Apr 2026 01:01:21 +0200
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Subject: Re: Fix bug with accessing to temporary tables of other sessions
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>,
 Alexander Korotkov <aekorotkov@gmail.com>,
 Soumya S Murali <soumyamurali.work@gmail.com>,
 Daniil Davydov <3danissimo@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>,
 Stepan Neretin <slpmcf@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>,
 Mohamed Ali <moali.pg@gmail.com>, Nazneen Jafri <jafrinazneen@gmail.com>,
 Shawn McCoy <shawn.the.mccoy@gmail.com>
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From: Jim Jones <jim.jones@uni-muenster.de>
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Hi David

On 25/04/2026 00:30, David G. Johnston wrote:
> If you can run the tests against v17 (that is the behavior we are trying
> to restore here, correct?) and v18 that would help demonstrate why the
> backpatch is needed.

Tests for PG18 and PG17:

== PG 18 ==

psql (18.3 (Debian 18.3-1.pgdg13+1))
Type "help" for help.

postgres=# \d pg_temp*.*
                    Table "pg_temp_36.t"
     Column      |  Type   | Collation | Nullable | Default
-----------------+---------+-----------+----------+---------
 generate_series | integer |           |          |

postgres=# SELECT * FROM pg_temp_36.t;
 generate_series
-----------------
(0 rows)


== PG 17 ==

psql (17.7 (Debian 17.7-3.pgdg13+1))
Geben Sie »help« für Hilfe ein.

postgres=# \d pg_temp*.*
                         Tabelle »pg_temp_13.t«
     Spalte      |   Typ   | Sortierfolge | NULL erlaubt? | Vorgabewert
-----------------+---------+--------------+---------------+-------------
 generate_series | integer |              |               |

postgres=# SELECT * FROM pg_temp_13.t;
 generate_series
-----------------
(0 Zeilen)


Until PG16 an error message was raised:

psql (16.13 (Debian 16.13-1.pgdg13+1))
Type "help" for help.

postgres=# \d pg_temp*.*
                    Table "pg_temp_3.t"
     Column      |  Type   | Collation | Nullable | Default
-----------------+---------+-----------+----------+---------
 generate_series | integer |           |          |

postgres=# SELECT * FROM pg_temp_3.t;
ERROR:  cannot access temporary tables of other sessions


Best, Jim