| From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Peter Geoghegan <pg(at)heroku(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Andres Freund <andres(at)2ndquadrant(dot)com> |
| Subject: | Re: Promise index tuples for UPSERT |
| Date: | 2014-10-07 14:16:45 |
| Message-ID: | CA+U5nM+ZtyfzKC3YLwpoNsXH9hLaeqA-2468FGbuE0_hB=28Eg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 7 October 2014 14:06, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> Is there a way of detecting that we are updating a unique constraint
>> column and then applying the HW locking only in that case? Or can we
>> only apply locking when we have multiple unique constraints on a
>> table?
>> If so, I would withdraw any objection to the HW locking technique.
>
> I'm not up on the details of what Peter's patch does with heavyweight
> locking, but I'd say it this way: if the patch uses heavyweight
> locking routinely, that's probably not going to scale well[1]. If
> the patch detects possible conflicts and uses heavyweight locking only
> in those cases and for the specific purpose of untangling those
> conflicts, then that might well be OK.
Yes, what I meant, just more clearly phrased. Thanks for the link.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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