| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Reducing some DDL Locks to ShareLock |
| Date: | 2008-11-10 00:11:21 |
| Message-ID: | 1226275881.27904.281.camel@ebony.2ndQuadrant |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Sun, 2008-11-09 at 17:12 -0500, Tom Lane wrote:
> Reviewing away ...
Thanks for reviewing.
> There's a fairly serious problem...
...
> Any thoughts about the best way to do it? My immediate inclination is
> to use heap_lock_tuple but it's a bit expensive.
Not sure how non-transactional tuple locking would/could work.
The user space solution to this problem is optimistic locking. i.e.
re-read the row immediately prior to the update. If row has changed,
keep re-reading it until it stays same, then update. Rely on block
locking to protect us. I'm tired and handwaving a lot.
Will think some more and report back.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support
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