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Message-ID: <a38fc771-c860-4605-8c44-d16e8aff2534@gmail.com>
Date: Fri, 10 Apr 2026 10:00:00 +0300
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Adding REPACK [concurrently]
To: Alvaro Herrera <alvherre@alvh.no-ip.org>,
 Amit Kapila <amit.kapila16@gmail.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
 Antonin Houska <ah@cybertec.at>,
 Srinath Reddy Sadipiralla <srinath2133@gmail.com>,
 Mihail Nikalayeu <mihailnikalayeu@gmail.com>,
 Matthias van de Meent <boekewurm+postgres@gmail.com>,
 Pg Hackers <pgsql-hackers@lists.postgresql.org>,
 Robert Treat <rob@xzilla.net>
References: <202604072027.gazfa2zt2l2j@alvherre.pgsql>
Content-Language: en-US
From: Alexander Lakhin <exclusion@gmail.com>
In-Reply-To: <202604072027.gazfa2zt2l2j@alvherre.pgsql>
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Hello Alvaro,

08.04.2026 00:38, Alvaro Herrera wrote:
> Okay.  I implemented that now, and here it is.  ...

Could you please look at an assertion failure produced by the following
script, starting from 0d3dba38c:?
createdb db1
createdb db2

echo "
CREATE TABLE t0 (a text);
BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
INSERT INTO t0 VALUES ('a');
SELECT pg_sleep(1);
" | psql db1 &

echo "
CREATE TABLE t1 (id int PRIMARY KEY);
CREATE TABLE t2 (id int PRIMARY KEY, a TEXT, FOREIGN KEY (id) REFERENCES t1);
SET min_parallel_table_scan_size = 1;
REPACK (CONCURRENTLY) t2;
" | psql db2
wait

It triggers for me:
TRAP: failed Assert("TransactionIdPrecedesOrEquals(TransactionXmin, RecentXmin)"), File: "procarray.c", Line: 2071, PID: 
3529520
postgres: parallel worker for PID 3529517 (ExceptionalCondition+0x69)[0x62f724b19c4c]
postgres: parallel worker for PID 3529517 (+0x522456)[0x62f72498e456]
postgres: parallel worker for PID 3529517 (GetSnapshotData+0x6b)[0x62f72498f50c]
postgres: parallel worker for PID 3529517 (GetNonHistoricCatalogSnapshot+0x4b)[0x62f724b5bd90]
postgres: parallel worker for PID 3529517 (GetCatalogSnapshot+0x20)[0x62f724b5ce7b]
postgres: parallel worker for PID 3529517 (systable_beginscan+0x10b)[0x62f7245c31e7]
postgres: parallel worker for PID 3529517 (+0x69e1e7)[0x62f724b0a1e7]
postgres: parallel worker for PID 3529517 (+0x69e5a6)[0x62f724b0a5a6]
postgres: parallel worker for PID 3529517 (+0x6a4d86)[0x62f724b10d86]
postgres: parallel worker for PID 3529517 (RelationIdGetRelation+0x83)[0x62f724b11208]
postgres: parallel worker for PID 3529517 (relation_open+0x1e)[0x62f72456c235]
...
2026-04-10 05:59:51.471 UTC [3529495] LOG:  background worker "parallel worker" (PID 3529520) was terminated by signal 
6: Aborted

Best regards,
Alexander
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    <div class="moz-cite-prefix">Hello Alvaro,<br>
      <br>
      08.04.2026 00:38, Alvaro Herrera wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:202604072027.gazfa2zt2l2j@alvherre.pgsql">
      <pre wrap="" class="moz-quote-pre">Okay.  I implemented that now, and here it is.  ...
</pre>
    </blockquote>
    <br>
    Could you please look at an assertion failure produced by the
    following<br>
    script, starting from 0d3dba38c:?<br>
    createdb db1<br>
    createdb db2<br>
    <br>
    echo "<br>
    CREATE TABLE t0 (a text);<br>
    BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;<br>
    INSERT INTO t0 VALUES ('a');<br>
    SELECT pg_sleep(1);<br>
    " | psql db1 &amp;<br>
    <br>
    echo "<br>
    CREATE TABLE t1 (id int PRIMARY KEY);<br>
    CREATE TABLE t2 (id int PRIMARY KEY, a TEXT, FOREIGN KEY (id)
    REFERENCES t1);<br>
    SET min_parallel_table_scan_size = 1;<br>
    REPACK (CONCURRENTLY) t2;<br>
    " | psql db2<br>
    wait<br>
    <br>
    It triggers for me:<br>
    TRAP: failed Assert("TransactionIdPrecedesOrEquals(TransactionXmin,
    RecentXmin)"), File: "procarray.c", Line: 2071, PID: 3529520<br>
    postgres: parallel worker for PID 3529517
    (ExceptionalCondition+0x69)[0x62f724b19c4c]<br>
    postgres: parallel worker for PID 3529517
    (+0x522456)[0x62f72498e456]<br>
    postgres: parallel worker for PID 3529517
    (GetSnapshotData+0x6b)[0x62f72498f50c]<br>
    postgres: parallel worker for PID 3529517
    (GetNonHistoricCatalogSnapshot+0x4b)[0x62f724b5bd90]<br>
    postgres: parallel worker for PID 3529517
    (GetCatalogSnapshot+0x20)[0x62f724b5ce7b]<br>
    postgres: parallel worker for PID 3529517
    (systable_beginscan+0x10b)[0x62f7245c31e7]<br>
    postgres: parallel worker for PID 3529517
    (+0x69e1e7)[0x62f724b0a1e7]<br>
    postgres: parallel worker for PID 3529517
    (+0x69e5a6)[0x62f724b0a5a6]<br>
    postgres: parallel worker for PID 3529517
    (+0x6a4d86)[0x62f724b10d86]<br>
    postgres: parallel worker for PID 3529517
    (RelationIdGetRelation+0x83)[0x62f724b11208]<br>
    postgres: parallel worker for PID 3529517
    (relation_open+0x1e)[0x62f72456c235]<br>
    ...<br>
    2026-04-10 05:59:51.471 UTC [3529495] LOG:  background worker
    "parallel worker" (PID 3529520) was terminated by signal 6: Aborted<br>
    <br>
    Best regards,<br>
    Alexander<br>
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