Thread: BUG #11517: the pg_stat_replication.sync_stat show sync when synchronous_commit is set to be off
BUG #11517: the pg_stat_replication.sync_stat show sync when synchronous_commit is set to be off
From
amutu@amutu.com
Date:
The following bug has been logged on the website: Bug reference: 11517 Logged by: the pg_stat_replication.sync_stat show sync when synchronous_commit is set to be off Email address: amutu@amutu.com PostgreSQL version: 9.2.4 Operating system: suse linux 10 x86_64 Description: from the doc,when synchronous_commit set to off or local,the commit will not wait the remote slave reveive data,so it is not asynchronous replication.but I find the pg_stat_replication wrongly report the sync_stat to sync.This can be confused for people. postgres=# select * from pg_stat_replication ; -[ RECORD 1 ]----+------------------------------ pid | 3213 usesysid | 16387 usename | rep application_name | sync_slave client_addr | 172.25.38.154 client_hostname | client_port | 54333 backend_start | 2014-09-29 15:17:19.927457+08 state | streaming sent_location | 21/A0F01C0 write_location | 21/A0F01C0 flush_location | 21/A0F01C0 replay_location | 21/A0EFC88 sync_priority | 1 sync_state | sync postgres=# show synchronous_standby_names ; -[ RECORD 1 ]-------------+----------------------- synchronous_standby_names | sync_slave,walreceiver postgres=# show synchronous_commit ; -[ RECORD 1 ]------+---- synchronous_commit | off
Re: BUG #11517: the pg_stat_replication.sync_stat show sync when synchronous_commit is set to be off
From
Michael Paquier
Date:
On Mon, Sep 29, 2014 at 4:45 PM, <amutu@amutu.com> wrote: > from the doc,when synchronous_commit set to off or local,the commit will > not > wait the remote slave reveive data,so it is not asynchronous > replication.but I > find the pg_stat_replication wrongly report the sync_stat to sync.This can This is not a bug, please refer to the documentation about synchronous_commit: http://www.postgresql.org/docs/devel/static/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT When synchronous_commit is set to off, local or remote_write, the master node does not wait for the confirmation from the sync standby that the WAL has been flushed to disk (for remote_write it waits for the write confirmation), and the standby is still considered as sync, of course if synchronous_standby_names is set. Regards, -- Michael
Re: BUG #11517: the pg_stat_replication.sync_stat show sync when synchronous_commit is set to be off
From
Jov
Date:
I read the doc before I submit the bug 2014=C4=EA9=D4=C229=C8=D5 4:03 PM=D3=DA "Michael Paquier" <michael.paquier@= gmail.com>=D0=B4=B5=C0=A3=BA > > > > On Mon, Sep 29, 2014 at 4:45 PM, <amutu@amutu.com> wrote: >> >> from the doc,when synchronous_commit set to off or local,the commit will not >> wait the remote slave reveive data,so it is not asynchronous replication.but I >> find the pg_stat_replication wrongly report the sync_stat to sync.This can > > This is not a bug, please refer to the documentation about synchronous_commit: > http://www.postgresql.org/docs/devel/static/runtime-config-wal.html#GUC-SYN= CHRONOUS-COMMIT > > When synchronous_commit is set to off, local or remote_write, the master node does not wait for the confirmation from the sync standby that the WAL has been flushed to disk (for remote_write it waits for the write confirmation), and the standby is still considered as sync, of course if synchronous_standby_names is set. I can't figure out this conclusion from the doc above.I appreciate it if you point me more specifically. > Regards, > -- > Michael