From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Re: making write location work (was: Efficient transaction-controlled synchronous replication) |
Date: | 2011-03-23 19:33:14 |
Message-ID: | AANLkTi=tBMFEhCKy3L6F7FOtg-2o0E32BYAiN1n04OZB@mail.gmail.com |
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Lists: | pgsql-hackers |
On Wed, Mar 23, 2011 at 7:29 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, Mar 23, 2011 at 2:43 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> On Wed, Mar 23, 2011 at 6:22 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Wed, Mar 23, 2011 at 12:10 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>>>>> Specifically, if we're not going to remove write location, then I
>>>>> think we need to apply something like the attached.
>>>>
>>>> The protocol supports different write/fsync values, so the view should
>>>> display them.
>>>
>>> That's exactly the point.
>>
>> No its not.
>>
>>> Currently, we have a protocol that supports
>>> different write and fsync values, but the code as written does not
>>> actually ever send a reply at any time when the two values can ever be
>>> different. So there is no point in sending both of them. The write
>>> location is completely redundant with the fsync location and therefore
>>> completely useless. We shouldn't bother sending the value twice, or
>>> displaying it twice, if it's absolutely 100% guaranteed to be
>>> identical in every case.
>>
>> As of 9.1, we now support other tools that use the protocol, so you
>> cannot assume you know what is being sent, just because one sender has
>> certain characteristics.
>
> Oh, really? Is this strictly hypothetical or is such a beast
> planned/already in existence?
Ask Magnus.
In any case, that's not the only argument for keeping it. We introduce
the view in this release and I would like it to stay the same from
now, since we know we will need that info later.
No more minor tweaks, please.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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