From: Fujii Masao <masao.fujii@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous replication.
Date: Fri, 18 Mar 2011 14:45:44 +0900
Message-ID: <AANLkTimAcuYBQZpmAyrHzzSFKVNQJKTvPpC-LRNx8WYL@mail.gmail.com> (raw)
In-Reply-To: <AANLkTikP1TZVHp68nqk6p7aMJ4S0tUTxdEnbDdguzL_8@mail.gmail.com>
References: <E1PwMns-00047O-UU@gemulon.postgresql.org>
<AANLkTikJmP+bo1N-mFUWEpJiV6_OKisYw512OGeTJUbm@mail.gmail.com>
<AANLkTinHrymKd56m5AfawCdujuNM6B2g_--9UiOSSKGx@mail.gmail.com>
<AANLkTinbJDsrkF9rsy8Wh_hrrrPP7CQaNcND_1A-aLMe@mail.gmail.com>
<AANLkTikP1TZVHp68nqk6p7aMJ4S0tUTxdEnbDdguzL_8@mail.gmail.com>
On Fri, Mar 18, 2011 at 2:52 AM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Thu, Mar 10, 2011 at 3:04 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>>> - /* Let the master know that we received some data. */
>>> - XLogWalRcvSendReply();
>>> - XLogWalRcvSendHSFeedback();
>>>
>>> This change completely eliminates the difference between write_location
>>> and flush_location in pg_stat_replication. If this change is reasoable, we
>>> should get rid of write_location from pg_stat_replication since it's useless.
>>> If not, this change should be reverted. I'm not sure whether monitoring
>>> the difference between write and flush locations is useful. But I guess that
>>> someone thought so and that code was added.
>>
>> I could go either way on this but clearly we need to do one or the other.
>
> I'm not really sure why this was part of the synchronous replication
> patch, but after mulling it over I think it's probably right to rip
> out write_location completely. There shouldn't ordinarily be much of
> a gap between write location and flush location, so it's probably not
> worth the extra network overhead to keep track of it. We might need
> to re-add some form of this in the future if we have a version of
> synchronous replication that only waits for confirmation of receipt
> rather than for confirmation of flush, but we don't have that in 9.1,
> so why bother?
>
> Barring objections, I'll go do that.
I agree to get rid of write_location.
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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To: pgsql-committers@postgresql.org
Cc: masao.fujii@gmail.com, robertmhaas@gmail.com, simon@2ndquadrant.com, pgsql-hackers@postgresql.org
Subject: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous replication.
In-Reply-To: <AANLkTimAcuYBQZpmAyrHzzSFKVNQJKTvPpC-LRNx8WYL@mail.gmail.com>
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