Re: Transactions involving multiple postgres foreign servers, take 2

On 2020/07/16 14:47, Masahiko Sawada wrote:
> On Tue, 14 Jul 2020 at 11:19, Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
>>
>>
>>
>> On 2020/07/14 9:08, Masahiro Ikeda wrote:
>>>> I've attached the latest version patches. I've incorporated the review
>>>> comments I got so far and improved locking strategy.
>>>
>>> Thanks for updating the patch!
>>
>> +1
>> I'm interested in these patches and now studying them. While checking
>> the behaviors of the patched PostgreSQL, I got three comments.
>
> Thank you for testing this patch!
>
>>
>> 1. We can access to the foreign table even during recovery in the HEAD.
>> But in the patched version, when I did that, I got the following error.
>> Is this intentional?
>>
>> ERROR:  cannot assign TransactionIds during recovery
>
> No, it should be fixed. I'm going to fix this by not collecting
> participants for atomic commit during recovery.

Thanks for trying to fix the issues!

I'd like to report one more issue. When I started new transaction
in the local server, executed INSERT in the remote server via
postgres_fdw and then quit psql, I got the following assertion failure.

TRAP: FailedAssertion("fdwxact", File: "fdwxact.c", Line: 1570)
0   postgres                            0x000000010d52f3c0 ExceptionalCondition + 160
1   postgres                            0x000000010cefbc49 ForgetAllFdwXactParticipants + 313
2   postgres                            0x000000010cefff14 AtProcExit_FdwXact + 20
3   postgres                            0x000000010d313fe3 shmem_exit + 179
4   postgres                            0x000000010d313e7a proc_exit_prepare + 122
5   postgres                            0x000000010d313da3 proc_exit + 19
6   postgres                            0x000000010d35112f PostgresMain + 3711
7   postgres                            0x000000010d27bb3a BackendRun + 570
8   postgres                            0x000000010d27af6b BackendStartup + 475
9   postgres                            0x000000010d279ed1 ServerLoop + 593
10  postgres                            0x000000010d277940 PostmasterMain + 6016
11  postgres                            0x000000010d1597b9 main + 761
12  libdyld.dylib                       0x00007fff7161e3d5 start + 1
13  ???                                 0x0000000000000003 0x0 + 3

Regards,


--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION