Re: weird hang while running in HS mode - Mailing list pgsql-hackers

From Fujii Masao
Subject Re: weird hang while running in HS mode
Date
Msg-id AANLkTilKfOdUhx5rZSPp8hx2GbLCyV0ecb-Arq1G9QgF@mail.gmail.com
Whole thread Raw
In response to weird hang while running in HS mode  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: weird hang while running in HS mode
List pgsql-hackers
On Thu, May 13, 2010 at 3:50 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> rhaas=# rollback;
> ROLLBACK
>
> So at this point, one would think that there are no locks hanging
> around anywhere.  Back to the standby:
>
> rhaas=# select * from pgbench_accounts;
> <really long hang>

I think that this problem happens because the WAL record of ROLLBACK
is not flushed to the disk immediately (i.e., until another transaction
flushes the WAL records in wal_buffers) when we execute the ROLLBACK
command. The walsender sends only the WAL records in the disk, so the
standby server would not be able to replay the ROLLBACK and not release
the lock.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center


pgsql-hackers by date:

Previous
From: "Joshua D. Drake"
Date:
Subject: Re: max_standby_delay considered harmful
Next
From: Fujii Masao
Date:
Subject: Re: comment needs to be updated for HS?