From: | "osumi(dot)takamichi(at)fujitsu(dot)com" <osumi(dot)takamichi(at)fujitsu(dot)com> |
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To: | 'Amit Kapila' <amit(dot)kapila16(at)gmail(dot)com> |
Cc: | Japin Li <japinli(at)hotmail(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Marco Nenciarini <marco(dot)nenciarini(at)2ndquadrant(dot)it>, Andres Freund <andres(at)anarazel(dot)de> |
Subject: | RE: Forget close an open relation in ReorderBufferProcessTXN() |
Date: | 2021-05-13 05:45:16 |
Message-ID: | OSBPR01MB48887462AE6127E1A08B6A3EED519@OSBPR01MB4888.jpnprd01.prod.outlook.com |
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Lists: | pgsql-hackers |
On Thursday, April 29, 2021 2:31 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> I am not so sure about it because I think we don't have any example of
> user_catalog_tables in the core code. This is the reason I was kind of looking
> towards Andres to clarify this. Right now, if the user performs TRUNCATE on
> user_catalog_table in synchronous mode then it will hang in case the
> decoding plugin takes even share lock on it. The main reason is that we allow
> decoding of TRUNCATE operation for user_catalog_tables. I think even if we
> want to allow decoding of other operations on user_catalog_table, the
> decoding of TRUNCATE should be prohibited but maybe we shouldn't allow
> decoding of any operation on such tables as we don't do it for system catalog
> tables.
I tried the following scenarios for trying to reproduce this.
Scenario1:
(1) set up 1 publisher and 1 subscriber
(2) create table with user_catalog_table = true on the pub
(3) insert some data to this table
(4) create publication for the table on the pub
(5) create table with user_catalog_table = true on the sub
(6) create subscription on the sub
(7) add synchronous_standby_names to publisher's configuration and restart the pub
(8) have 1 session to hold a lock to the user_catalog_table on the pub in access share mode
(9) have another session to truncate the user_catalog_table on the pub
Here, It keeps waiting but I'm not sure this is the scenario described above,
since this deadlock is caused by (8)'s lock.
Scenario2:
(1) set up 1 publisher and 1 subscriber
(2) create table with user_catalog_table = true on the pub
(3) insert some data to this table
(4) create publication for the table on the pub
(5) create table with user_catalog_table = true on the sub
(6) create subscription on the sub
(7) add synchronous_standby_names to publisher's configuration and restart the pub
(8) have a session to truncate the user_catalog_table on the pub
Scenario 2 was successful.
Are these the scenario you have in mind,
if not please let me know for the missing steps.
I would like to reproduce the scenario and write a patch to fix this.
Best Regards,
Takamichi Osumi
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