| From: | Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Noah Misch <noah(at)leadboat(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: CREATE INDEX CONCURRENTLY does not index prepared xact's data |
| Date: | 2021-08-07 15:33:18 |
| Message-ID: | DBD361BB-4327-4143-A849-36A262B22CEE@yandex-team.ru |
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| Lists: | pgsql-bugs |
> 6 авг. 2021 г., в 23:03, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> написал(а):
>
> But how to get why something did not happen?
> During GetLockConflicts() proclocks SHMQueue do not include locks of concurrently running xid within PrepareTransaction() [seems like it's with PostPrepare_locks(), but I'm not sure].
> The problem is reproducible within 1 second by the script leading to amcheck-detected corruption.
Ok, finally I've figured out this charade.
AtPrepare_Locks() transfers fast-path locks to normal locks pointing to PGPROC with xid in a process of conversion to 2PC.
ProcArrayClearTransaction(MyProc) resets xid int PGROCs.
GetLockConflicts() sees empty xid and vxid.
PostPrepare_Locks(xid) hids things with new PGPROC for 2PC.
PFA PoC fix. But I'm entirely not sure it's OK to do reorder things at PrepareTransaction() this way.
Thanks!
Best regards, Andrey Borodin.
| Attachment | Content-Type | Size |
|---|---|---|
| v9-0001-Introduce-TAP-test-for-2PC-with-CIC-behavior.patch | application/octet-stream | 7.0 KB |
| v9-0004-PoC-fix-clear-xid.patch | application/octet-stream | 1.0 KB |
| v9-0003-Fix-CREATE-INDEX-CONCURRENTLY-in-precence-of-vxid.patch | application/octet-stream | 8.5 KB |
| v9-0002-PoC-fix-for-race-in-RelationBuildDesc-and-relcach.patch | application/octet-stream | 2.1 KB |
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