[pgpool-general: 6378] Re: kind mismatch among backends, savepoint with psqlodbc

[Bo Peng]

Hi,

On Tue, 18 Dec 2018 09:20:02 +0100
Jaime Soler <jaime.soler at gmail.com> wrote:

> Hi,
> 
> I have two server postgresql 10.X configured with streaming replication and
> two pgpool server in front of pg, watchdog to control pgpool ha and vip to
> access pgpool service.
> I am getting this error at pgpool log:
> Dec 17 03:18:01 XXXX1 pgpool12142: [20193-1] 2018-12-17 03:18:01: pid
> 12142: LOG: pool_send_and_wait: Error or notice message from backend: : DB
> node id: 1 backend pid: 24931 statement: "SAVEPOINT
> _EXEC_SVP_0x55594d617a10" message: "la orden SAVEPOINT sólo puede ser usada
> en bloques de transacción"
> Dec 17 03:18:01 XXXX1 pgpool12142: [20193-2] 2018-12-17 03:18:01: pid
> 12142: LOCATION: pool_proto_modules.c:3317
> Dec 17 03:18:01 XXXX1 pgpool12142: [20194-1] 2018-12-17 03:18:01: pid
> 12142: WARNING: packet kind of backend 1 ['E'] does not match with
> master/majority nodes packet kind ['C']
> Dec 17 03:18:01 XXXX1 pgpool12142: [20194-2] 2018-12-17 03:18:01: pid
> 12142: LOCATION: pool_process_query.c:3635
> Dec 17 03:18:01 XXXX1 pgpool12142: [20195-1] 2018-12-17 03:18:01: pid
> 12142: FATAL: failed to read kind from backend
> Dec 17 03:18:01 XXXX1 pgpool12142: [20195-2] 2018-12-17 03:18:01: pid
> 12142: DETAIL: kind mismatch among backends. Possible last query was:
> "SAVEPOINT _EXEC_SVP_0x55594d617a10" kind details are: 0[C] 1[E: la orden
> SAVEPOINT sólo puede ser usada en bloques de transacción]

This message means SAVEPOITN can only be used in a transaction block.
It seems that "BEGIN" statment was not executed at backend 1.

Could you show me more log including "BEGIN" statment?

> I think that there is an application that is connecting to pgpool using
> postgresql odbc driver because I have found the same savepoint name pattern
> at psqlodbc repository:
> https://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=execute.c;hb=e0e512f5c18750e747164d9110bcf6752d013126#l399
> https://git.postgresql.org/gitweb/?p=psqlodbc.git;a=blob;f=execute.c;hb=e0e512f5c18750e747164d9110bcf6752d013126#l599
> And I suppose that the Level of rollback on errors, it was set as Statement
> =2
> 
> Config doc of odbc driver ( https://odbc.postgresql.org/docs/config.html )
> Specifies what to rollback should an error occur.
> Nop(0): Don't rollback anything and let the application handle the error.
> Transaction(1): Rollback the entire transaction.
> Statement(2): Rollback the statement.
> Setup note: This specification is set up with the PROTOCOL option parameter.
> PROTOCOL=7.4-(0|1|2)
> default value is Statement (it is Transaction for servers before 8.0).
> 
> Looking at the log, backend 1 is got an Error  ['E']  and backend 0 had a
> complete command ['C'] packet kind to there was a kind mismatch among
> backends. But I don't understand why pgpool was getting that error. Under
> my knowledge our pgpool cluster has enabled load balancing so if a
> connection start/begin a transaction pgpool routes this to master node and
> routes the whole transaction to the master node and the previous error
> hasn't be thrown by pgpool.  Could you help to find out why is failing ?
> 
> Thanks


-- 
Bo Peng <pengbo at sraoss.co.jp>
SRA OSS, Inc. Japan