On 2007-04-30, "John D. Burger" <[EMAIL PROTECTED]> wrote:
> Andrew - Supernews wrote:
>
>>> Anyone have any ideas on how to handle a work queue?
>>
>> Advisory locks (userlocks in pre-8.2).
>
> Can someone explain why these are a better fit than whatever locks
> SELECT FOR UPDATE acquires?
They
On 5/1/07, Alban Hertroys <[EMAIL PROTECTED]> wrote:
Whether that improves your performance pretty much depends on the queue
sizes, the frequency of processing and the load processing causes...
Heh, I just realize we have a work queue table here as well, I'd like to
know the result.
the optimiz
Merlin Moncure wrote:
> take another look at my example. there are two things happening that
> have to be logically combined into one operation. one is checking the
> last_value column of two sequences and the other is the nextval().
> the advisory lock protects against this:
>
> session a: worke
On 5/1/07, Alban Hertroys <[EMAIL PROTECTED]> wrote:
Merlin Moncure wrote:
> ok, here's an example. I was thinking that my sequence idea might not
> be safe because of race conditions revolving around querying the
> sequence table. Here is how I might use advisory locks eliminate the
I've seen
Merlin Moncure wrote:
> ok, here's an example. I was thinking that my sequence idea might not
> be safe because of race conditions revolving around querying the
> sequence table. Here is how I might use advisory locks eliminate the
I've seen your name pop up regularly on this list (or are you fr
On 4/30/07, John D. Burger <[EMAIL PROTECTED]> wrote:
Can someone explain why [advisory locks] are a better fit than whatever locks
SELECT FOR UPDATE acquires?
ok, here's an example. I was thinking that my sequence idea might not
be safe because of race conditions revolving around querying the
On 4/30/07, John D. Burger <[EMAIL PROTECTED]> wrote:
Andrew - Supernews wrote:
>> Anyone have any ideas on how to handle a work queue?
>
> Advisory locks (userlocks in pre-8.2).
Can someone explain why these are a better fit than whatever locks
SELECT FOR UPDATE acquires?
They are fast, and
Andrew - Supernews wrote:
Anyone have any ideas on how to handle a work queue?
Advisory locks (userlocks in pre-8.2).
Can someone explain why these are a better fit than whatever locks
SELECT FOR UPDATE acquires?
Thanks.
- John D. Burger
MITRE
---(end of br
On 2007-04-26, Steve Crawford <[EMAIL PROTECTED]> wrote:
> Anyone have any ideas on how to handle a work queue?
Advisory locks (userlocks in pre-8.2).
--
Andrew, Supernews
http://www.supernews.com - individual and corporate NNTP services
---(end of broadcast)
Steve Crawford wrote:
begin;
select item-id, item-info
from the-queue
where available
order by priority
limit 1
for update;
update the-queue
set status = 'assigned'
where item-id = previously-selected-item-id;
commit;
I do something similar in one of my apps:
BEGIN;
up
[EMAIL PROTECTED] ("John D. Burger") writes:
> I wrote:
>
>> I use a variant of The Tom Lane Solution previously pointed to,
>> your Plan 1 is very similar.
>
> Hmm, per that pointed-to post:
>
> http://archives.postgresql.org/pgsql-general/2003-05/msg00351.php
>
> I decided to run a periodic vac
I decided to run a periodic vacuum on my work queue. Lo and behold,
I get this:
ERROR: tuple concurrently updated
Which PG version is this, and do you have autovacuum enabled?
7.4.8, so no autovac, right?
In addition, all of my workers locked up, apparently indefinitely.
[ squint..
"John D. Burger" <[EMAIL PROTECTED]> writes:
> I decided to run a periodic vacuum on my work queue. Lo and behold,
> I get this:
>ERROR: tuple concurrently updated
Which PG version is this, and do you have autovacuum enabled? Awhile
back it was possible to get this error if autovac and a
I wrote:
I use a variant of The Tom Lane Solution previously pointed to,
your Plan 1 is very similar.
Hmm, per that pointed-to post:
http://archives.postgresql.org/pgsql-general/2003-05/msg00351.php
I decided to run a periodic vacuum on my work queue. Lo and behold,
I get this:
ERR
Steve Crawford wrote:
Anyone have any ideas on how to handle a work queue? I've been
thinking
about optimizing this process for quite a while.
I use a variant of The Tom Lane Solution previously pointed to, your
Plan 1 is very similar.
This does not produce desirable results. In the case
On 4/27/07, Merlin Moncure <[EMAIL PROTECTED]> wrote:
how about this:
create table job(job_id int, [...])
create sequence worker;
couple typos: here is an example that works:
create table job(job_id serial);
create sequence worker;
-- get next available job
create function next_job() returns
On 4/27/07, Steve Crawford <[EMAIL PROTECTED]> wrote:
Anyone have any ideas on how to handle a work queue? I've been thinking
about optimizing this process for quite a while.
Basically, my queue table consists of a few-hundred-thousand records
describing "things to do". To pare things to the min
On 4/27/07, Steve Crawford <[EMAIL PROTECTED]> wrote:
Anyone have any ideas on how to handle a work queue? I've been thinking
about optimizing this process for quite a while.
I have been using PostgreSQL for the exact same thing, except I have
not yet reached the stage where I need to process q
Anyone have any ideas on how to handle a work queue? I've been thinking
about optimizing this process for quite a while.
Basically, my queue table consists of a few-hundred-thousand records
describing "things to do". To pare things to the minimum, a queue record
can be considered to have a status
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