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Re: BUG #5837: PQstatus() fails to report lost connection

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: "Murray S(dot) Kucherawy" <msk(at)cloudmark(dot)com>, "pgsql-bugs(at)postgresql(dot)org" <pgsql-bugs(at)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: BUG #5837: PQstatus() fails to report lost connection
Date: 2011-01-25 19:09:28
Message-ID: AANLkTikZr7Zg-BxC5bSNtzskBUK-nn_dOcTxVOnGLF_P@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-bugs
On Tue, Jan 25, 2011 at 10:54 AM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> I think this patch would only be adding to the confusion.  When
>> PQgetResult() is called, we read enough data from the connection
>> to create and return one result object.  It's true that this
>> doesn't necessarily detect an EOF, but IIUC calling PQgetResult()
>> again is just ONE way that you could trigger another read against
>> the socket, not the only one.  I think it would also work to call
>> PQconsumeInput(), for example.
>
> I find it hard to reconcile the above with this:
>
> http://archives.postgresql.org/message-id/6493.1295882981@sss.pgh.pa.us
>
> and the quote from our documentation referenced here:
>
> http://archives.postgresql.org/message-id/4D3D67600200002500039B2C@gw.wicourts.gov

IIUC, Tom's point was that doing it that way would detect the error,
not that it was the ONLY way to detect the error.

But it's easily testable.

>> I think the real, underlying problem here is that Murray would
>> like a behavior change
>
> More than that I think he wants to be able to read the manual and
> know what will work, without spending loads of time getting in tune
> with The Tao of Libpq.  Based on his initial reading of the docs he
> expected different behavior; that can be fixed by changing the
> behavior or changing the docs.

That is why I suggested the type of doc correction that I thought
would be most helpful and accurate.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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Subject: Multicolun index creation never completes on 9.0.1/solaris
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Subject: Re: BUG #5837: PQstatus() fails to report lost connection

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