From: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
To: Dilip Kumar <dilipbalaut@gmail.com>
To: sveinn.sveinsson@gmail.com
Cc: pgsql-bugs@postgresql.org
Subject: Re: BUG #14657: Server process segmentation fault in v10, May 10th dev snapshot
Date: Thu, 18 May 2017 10:49:38 +0900
Message-ID: <e261ebf9-e916-8554-5e72-6e9348fd78fc@lab.ntt.co.jp> (raw)
In-Reply-To: <CAFiTN-uKBPY6cUVnea-OKbX=GpHj68jBqpZtTYdYEc_72UX+cQ@mail.gmail.com>
References: <20170517141151.1435.79890@wrigleys.postgresql.org>
<CAFiTN-uKBPY6cUVnea-OKbX=GpHj68jBqpZtTYdYEc_72UX+cQ@mail.gmail.com>
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On 2017/05/18 2:14, Dilip Kumar wrote:
> On Wed, May 17, 2017 at 7:41 PM, <sveinn.sveinsson@gmail.com> wrote:
>> (gdb) bt
>> #0 0x000000000061ab1b in list_nth ()
>> #1 0x00000000005e4081 in ExecLockNonLeafAppendTables ()
>> #2 0x00000000005f4d52 in ExecInitMergeAppend ()
>> #3 0x00000000005e0365 in ExecInitNode ()
>> #4 0x00000000005f35a7 in ExecInitLimit ()
>> #5 0x00000000005e00f3 in ExecInitNode ()
>> #6 0x00000000005dd207 in standard_ExecutorStart ()
>> #7 0x00000000006f96d2 in PortalStart ()
>> #8 0x00000000006f5c7f in exec_simple_query ()
>> #9 0x00000000006f6fac in PostgresMain ()
>> #10 0x0000000000475cdc in ServerLoop ()
>> #11 0x0000000000692ffa in PostmasterMain ()
>> #12 0x0000000000476600 in main ()
Thanks for the test case Sveinn and thanks Dilip for analyzing.
> Seems like the issue is that the plans under multiple subroots are
> pointing to the same partitioned_rels.
That's correct.
> If I am not getting it wrong "set_plan_refs(PlannerInfo *root, Plan
> *plan, int rtoffset)" the rtoffset is specific to the subroot. Now,
> problem is that set_plan_refs called for different subroot is updating
> the same partition_rel info and make this value completely wrong which
> will ultimately make ExecLockNonLeafAppendTables to access the out of
> bound "rte" index.
Yes.
> set_plan_refs
> {
> [clipped]
> case T_MergeAppend:
> {
> [clipped]
>
> foreach(l, splan->partitioned_rels)
> {
> lfirst_int(l) += rtoffset;
>
>
> I think the solution should be that create_merge_append_path make the
> copy of partitioned_rels list?
Yes, partitioned_rels should be copied.
> Attached patch fixes the problem but I am not completely sure about the fix.
Thanks for creating the patch, although I think a better fix would be to
make get_partitioned_child_rels() do the list_copy. That way, any other
users of partitioned_rels will not suffer the same issue. Attached patch
implements that, along with a regression test.
Added to the open items.
Thanks,
Amit
Attachments:
0001-Fix-crash-when-partitioned-table-Append-referenced-i.patch (text/x-diff, 0B) download
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To: pgsql-bugs@postgresql.org
Cc: Langote_Amit_f8@lab.ntt.co.jp, dilipbalaut@gmail.com, sveinn.sveinsson@gmail.com
Subject: Re: BUG #14657: Server process segmentation fault in v10, May 10th dev snapshot
In-Reply-To: <e261ebf9-e916-8554-5e72-6e9348fd78fc@lab.ntt.co.jp>
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