| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Dan Ports <drkp(at)csail(dot)mit(dot)edu> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: SSI non-serializable UPDATE performance |
| Date: | 2011-05-07 01:55:38 |
| Message-ID: | BANLkTimTNxYRtNJiERJPm+xoddHqRsGO1A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Apr 29, 2011 at 3:23 AM, Dan Ports <drkp(at)csail(dot)mit(dot)edu> wrote:
> On Thu, Apr 28, 2011 at 06:45:54PM +0200, Robert Haas wrote:
>> Yeah, I think Dan's notes about memory ordering would be good to include.
>
> I left it out initially because I didn't want to make things more
> confusing. As far as memory ordering is concerned, this is the same
> story as anything else that uses lwlocks: the spinlock memory barrier
> prevents memory accesses from being reordered before the lock is
> acquired. The only unusual thing here is that the lock in question
> isn't the one that protects the variable we're reading.
>
> But I'm OK with adding a comment if you think it helps. Patch attached.
Looks good. Committed.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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