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Message-ID: <e72c94d9-e5f9-4753-9bc1-69d72bd54b8a@gmail.com>
Date: Fri, 14 Feb 2025 23:00:00 +0200
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Subject: Re: generic plans and "initial" pruning
To: Amit Langote <amitlangote09@gmail.com>, Tomas Vondra <tomas@vondra.me>
Cc: Robert Haas <robertmhaas@gmail.com>,
 Alvaro Herrera <alvherre@alvh.no-ip.org>, Andres Freund
 <andres@anarazel.de>, Daniel Gustafsson <daniel@yesql.se>,
 David Rowley <dgrowleyml@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>,
 Thom Brown <thom@linux.com>, Tom Lane <tgl@sss.pgh.pa.us>
References: <CA+HiwqFpZ80UJKr4tZus4Omgg7YESzFXKSwSHRW2Ap2=XSVyUA@mail.gmail.com>
 <CA+HiwqH45ZCQkWoLzjOyS6bQ9QsF7yDCKVwiEUtB_RwPFwLmQg@mail.gmail.com>
 <CA+HiwqHRRFQN6yZ54fBydOTM6ncqZBCmewZ6n519RjRdDsO44g@mail.gmail.com>
 <54c35fb9-da3a-4754-ab8c-46ed0b612465@vondra.me>
 <CA+HiwqH8N-SxEB6SysEBsYNgV_KJs66k9Z2SNmqVzbBP-60yWg@mail.gmail.com>
 <684c70d7-180e-461d-9377-600c2db581ba@vondra.me>
 <CA+HiwqEmG9YCQvG6uux7sO=jKFSAW6hA4Ea-ymfD+JhJAe4PWQ@mail.gmail.com>
 <CA+HiwqE2FfJfH=siLiR3kJ13tmXZORAGTWsZc2r52o1_5BDv+g@mail.gmail.com>
 <bfcc1b78-aa39-4356-8f42-b8cfb9733d6e@vondra.me>
 <CA+HiwqFhkpXHAA=4NY5SqYXX08uq=nYtXcSByNZF=2MAy1UA7A@mail.gmail.com>
 <CA+HiwqHCcSoYfpMjFshaU1bj6NjreiDvMSDpVSeBmqk-kbWrPw@mail.gmail.com>
 <CA+HiwqHOejJk0_qMuM5g38h70hY_JvHMAKwnH3k=urfTXauPQA@mail.gmail.com>
 <CA+HiwqFsGKM82oaMby3VWYXf_XFpDAMeT+6SXgj-45HpTrS1dA@mail.gmail.com>
 <CA+HiwqFA5hUWYktt3VMh4zQOYMxqH-MpdX8eemfM+o-9dY-zbQ@mail.gmail.com>
 <CA+HiwqEn7bbUXaXO=SmUujBjJSHfS31cwQroHRBwT0sR=66bgg@mail.gmail.com>
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From: Alexander Lakhin <exclusion@gmail.com>
In-Reply-To: <CA+HiwqEn7bbUXaXO=SmUujBjJSHfS31cwQroHRBwT0sR=66bgg@mail.gmail.com>
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Hello Amit,

06.02.2025 04:35, Amit Langote wrote:
> I plan to push 0001 tomorrow, barring any objections.
>

Please try the following script:
CREATE TABLE pt (a int, b int) PARTITION BY range (a);
CREATE TABLE tp1 PARTITION OF pt FOR VALUES FROM (1) TO (2);
CREATE TABLE tp2 PARTITION OF pt FOR VALUES FROM (2) TO (3);

MERGE INTO pt
USING (SELECT pg_backend_pid() AS pid) AS q JOIN tp1 ON (q.pid = tp1.a)
ON pt.a = tp1.a
WHEN MATCHED THEN DELETE;

which fails for me with segfault:
Program terminated with signal SIGSEGV, Segmentation fault.
#0  ExecInitMerge (mtstate=0x5a9b9fbccae0, estate=0x5a9b9fbcbe20) at nodeModifyTable.c:3680
3680                    relationDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
(gdb) bt
#0  ExecInitMerge (mtstate=0x5a9b9fbccae0, estate=0x5a9b9fbcbe20) at nodeModifyTable.c:3680
#1  0x00005a9b67e6dfb5 in ExecInitModifyTable (node=0x5a9b9fbd5858, estate=0x5a9b9fbcbe20, eflags=0) at 
nodeModifyTable.c:4906
#2  0x00005a9b67e273f7 in ExecInitNode (node=0x5a9b9fbd5858, estate=0x5a9b9fbcbe20, eflags=0) at execProcnode.c:177
#3  0x00005a9b67e1b9d2 in InitPlan (queryDesc=0x5a9b9fbb9970, eflags=0) at execMain.c:1092
#4  0x00005a9b67e1a524 in standard_ExecutorStart (queryDesc=0x5a9b9fbb9970, eflags=0) at execMain.c:268
#5  0x00005a9b67e1a223 in ExecutorStart (queryDesc=0x5a9b9fbb9970, eflags=0) at execMain.c:142
...

starting from cbc127917.

(I've discovered this anomaly with SQLsmith.)

Best regards,
Alexander Lakhin
Neon (https://neon.tech)
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    <div class="moz-cite-prefix">Hello Amit,<br>
      <br>
      06.02.2025 04:35, Amit Langote wrote:<span
      style="white-space: pre-wrap">
</span><span style="white-space: pre-wrap">
</span></div>
    <blockquote type="cite"
cite="mid:CA+HiwqEn7bbUXaXO=SmUujBjJSHfS31cwQroHRBwT0sR=66bgg@mail.gmail.com">
      <pre wrap="" class="moz-quote-pre">I plan to push 0001 tomorrow, barring any objections.

</pre>
    </blockquote>
    <br>
    Please try the following script:<br>
    CREATE TABLE pt (a int, b int) PARTITION BY range (a);<br>
    CREATE TABLE tp1 PARTITION OF pt FOR VALUES FROM (1) TO (2);<br>
    CREATE TABLE tp2 PARTITION OF pt FOR VALUES FROM (2) TO (3);<br>
    <br>
    MERGE INTO pt<br>
    USING (SELECT pg_backend_pid() AS pid) AS q JOIN tp1 ON (q.pid =
    tp1.a)<br>
    ON pt.a = tp1.a<br>
    WHEN MATCHED THEN DELETE;<br>
    <br>
    which fails for me with segfault: <br>
    Program terminated with signal SIGSEGV, Segmentation fault.<br>
    #0  ExecInitMerge (mtstate=0x5a9b9fbccae0, estate=0x5a9b9fbcbe20) at
    nodeModifyTable.c:3680<br>
    3680                    relationDesc =
    RelationGetDescr(resultRelInfo-&gt;ri_RelationDesc);<br>
    (gdb) bt<br>
    #0  ExecInitMerge (mtstate=0x5a9b9fbccae0, estate=0x5a9b9fbcbe20) at
    nodeModifyTable.c:3680<br>
    #1  0x00005a9b67e6dfb5 in ExecInitModifyTable (node=0x5a9b9fbd5858,
    estate=0x5a9b9fbcbe20, eflags=0) at nodeModifyTable.c:4906<br>
    #2  0x00005a9b67e273f7 in ExecInitNode (node=0x5a9b9fbd5858,
    estate=0x5a9b9fbcbe20, eflags=0) at execProcnode.c:177<br>
    #3  0x00005a9b67e1b9d2 in InitPlan (queryDesc=0x5a9b9fbb9970,
    eflags=0) at execMain.c:1092<br>
    #4  0x00005a9b67e1a524 in standard_ExecutorStart
    (queryDesc=0x5a9b9fbb9970, eflags=0) at execMain.c:268<br>
    #5  0x00005a9b67e1a223 in ExecutorStart (queryDesc=0x5a9b9fbb9970,
    eflags=0) at execMain.c:142<br>
    ...<br>
    <br>
    starting from cbc127917.<br>
    <br>
    (I've discovered this anomaly with SQLsmith.)<br>
    <br>
    Best regards,<br>
    Alexander Lakhin
    <br>
    Neon (<a class="moz-txt-link-freetext" href="https://neon.tech">https://neon.tech</a>)
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