Re: [HACKERS] make async slave to wait for lsn to be replayed

From: Andres Freund <andres(at)anarazel(dot)de>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Ivan Kartyshov <i(dot)kartyshov(at)postgrespro(dot)ru>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] make async slave to wait for lsn to be replayed
Date: 2018-03-02 00:47:14
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On 2018-02-02 19:41:37 +0000, Simon Riggs wrote:
> On 2 February 2018 at 18:46, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > On Fri, Feb 2, 2018 at 3:46 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> >> In PG11, I propose the following command, sticking mostly to Ants'
> >> syntax, and allowing to wait for multiple events before it returns. It
> >> doesn't hold snapshot and will not get cancelled by Hot Standby.
> >>
> >> WAIT FOR event [, event ...] options
> >>
> >> event is
> >> LSN value
> >> TIMESTAMP value
> >>
> >> options
> >> TIMEOUT delay
> >> UNTIL TIMESTAMP timestamp
> >> (we have both, so people don't need to do math, they can use whichever
> >> they have)
> >
> > WAIT FOR TIMEOUT sounds a lot like SELECT pg_sleep_for(), and WAIT
> > UNTIL TIMESTAMP sounds a lot like SELECT pg_sleep_until().
> Yes, it sounds very similar. It's the behavior that differs; I read
> and agreed with yours and Thomas' earlier comments on that point.
> As pointed out upthread, the key difference is whether it gets
> cancelled on Hot Standby and whether you can call it in a non-READ
> COMMITTED transaction.

Given that nobody has updated the patch or even discussed doing so, I
assume this would CF issue should now appropriately be classified as
returned with feedback?


Andres Freund

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message David Rowley 2018-03-02 00:48:00 Re: Parallel Aggregates for string_agg and array_agg
Previous Message Andres Freund 2018-03-02 00:30:00 Re: Removing shm_mq.c's volatile qualifiers