Re: Slow response of PostgreSQL

From: Bill Moran <wmoran(at)potentialtech(dot)com>
To: "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com>
Cc: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Saleem Burhani Baloch <peseek(at)khi(dot)wol(dot)net(dot)pk>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Slow response of PostgreSQL
Date: 2004-02-18 02:21:31
Message-ID: 4032CC2B.9030208@potentialtech.com
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scott.marlowe wrote:
> On Wed, 18 Feb 2004, Christopher Kings-Lynne wrote:
>
>>>>>1- How can I lock a single record so that other users can only read
>>>>>it. ??
>>>>
>>>>
>>>>You cannot do that in PostgreSQL.
>>>
>>>
>>>How about SELECT ... FOR UPDATE?
>>
>>No, because users cannot read the locked row in that case.
>
> I just tested it (within transactions) and it appeared that I could still
> view the rows selected for update.

Thank you. I was just about to test it myself.

The user's guide, section 9.3.2 states that this is the case: i.e. select
for update will prevent concurrent updating of the row, while allowing
queries utilizing that row to succeed.

--
Bill Moran
Potential Technologies
http://www.potentialtech.com

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