Re: Logical Replication of sequences

On Fri, 5 Jul 2024 at 09:46, Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
>
> Hi Vignesh.
>
> After applying the v20240703-0003 patch, I was always getting errors
> when running the subscription TAP tests.
>
> # +++ tap check in src/test/subscription +++
> t/001_rep_changes.pl ............... ok
> t/002_types.pl ..................... ok
> t/003_constraints.pl ............... ok
> t/004_sync.pl ...................... ok
> t/005_encoding.pl .................. ok
> t/006_rewrite.pl ................... ok
> t/007_ddl.pl ....................... 3/?
> # Failed test 'Alter subscription set publication throws warning for
> non-existent publication'
> # at t/007_ddl.pl line 67.
> Bailout called. Further testing stopped: pg_ctl stop failed
> # Tests were run but no plan was declared and done_testing() was not seen.
> FAILED--Further testing stopped: pg_ctl stop failed
> make: *** [check] Error 255
>
> ~~~
>
> The publisher log shows an Assert TRAP occurred:
>
> 2024-07-04 18:15:40.089 AEST [745] mysub1 LOG: statement: SELECT
> DISTINCT s.schemaname, s.sequencename
> FROM pg_catalog.pg_publication_sequences s
> WHERE s.pubname IN ('mypub', 'non_existent_pub', 'non_existent_pub1',
> 'non_existent_pub2')
> TRAP: failed Assert("IsA(list, OidList)"), File:
> "../../../src/include/nodes/pg_list.h", Line: 323, PID: 745
>
> ~~~
>
> A debugging backtrace looks like below:
>
> Core was generated by `postgres: publisher: walsender postgres
> postgres [local] SELECT '.
> Program terminated with signal 6, Aborted.
> #0 0x00007f36f44f02c7 in raise () from /lib64/libc.so.6
> Missing separate debuginfos, use: debuginfo-install
> glibc-2.17-260.el7_6.6.x86_64 pcre-8.32-17.el7.x86_64
> (gdb) bt
> #0 0x00007f36f44f02c7 in raise () from /lib64/libc.so.6
> #1 0x00007f36f44f19b8 in abort () from /lib64/libc.so.6
> #2 0x0000000000bb8be1 in ExceptionalCondition (conditionName=0xc7aa6c
> "IsA(list, OidList)",
> fileName=0xc7aa10 "../../../src/include/nodes/pg_list.h",
> lineNumber=323) at assert.c:66
> #3 0x00000000005f2c57 in list_nth_oid (list=0x27948f0, n=0) at
> ../../../src/include/nodes/pg_list.h:323
> #4 0x00000000005f5491 in pg_get_publication_sequences
> (fcinfo=0x2796a00) at pg_publication.c:1334
> #5 0x0000000000763d10 in ExecMakeTableFunctionResult
> (setexpr=0x27b2fd8, econtext=0x27b2ef8, argContext=0x2796900,
> ...
>
> Something goes wrong indexing into that 'sequences' list.
>
> 1329 funcctx = SRF_PERCALL_SETUP();
> 1330 sequences = (List *) funcctx->user_fctx;
> 1331
> 1332 if (funcctx->call_cntr < list_length(sequences))
> 1333 {
> 1334 Oid relid = list_nth_oid(sequences, funcctx->call_cntr);
> 1335
> 1336 SRF_RETURN_NEXT(funcctx, ObjectIdGetDatum(relid));
> 1337 }

I was not able to reproduce this issue after several runs, but looks
like sequences need to be initialized here.

> Perhaps now it is time to create a CF entry for this thread because
> the cfbot could have detected the error earlier.

I have added a commitfest entry for the same at [1].

The v20240705 version patch attached at [2] has the change for the same.

[1] - https://commitfest.postgresql.org/49/5111/
[2] - https://www.postgresql.org/message-id/CALDaNm3WvLUesGq54JagEkbBh4CBfMoT84Rw7HjL8KML_BSzPw%40mail.gmail.com

Regards,
Vignesh