Re: generic plans and "initial" pruning

Hi Alexander,

On Sat, Feb 15, 2025 at 6:00 AM Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
>
> 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.)

Thanks! It looks like I missed updating the MERGE-related lists in ModifyTable.

I've attached a fix with a test added based on your example. I plan to
push this on Monday.

--
Thanks, Amit Langote