| From: | Peter Geoghegan <pg(at)heroku(dot)com> |
|---|---|
| To: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: INSERT...ON DUPLICATE KEY LOCK FOR UPDATE |
| Date: | 2013-12-31 10:18:06 |
| Message-ID: | CAM3SWZSaoiCmLLD_tez9riFVHiOfQD7J+hbBBBcaUjrSUsXdLw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Dec 31, 2013 at 12:52 AM, Heikki Linnakangas
<hlinnakangas(at)vmware(dot)com> wrote:
>> Are you suggesting that I lock the tuple only (say, through a special
>> LockPromiseTuple() call), or lock the tuple *and* call
>> XactLockTableWait() afterwards? You and Robert don't seem to be in
>> agreement about which here.
>
> I meant the latter, ie. grab the new kind of lock first, then check if the
> tuple is still there, and then call XactLockTableWait() as usual.
I don't follow this either. Through what exact mechanism does the
waiter know that there was a wait on the
PromiseTupleInsertionLockAcquire() call, and so it should not wait on
XactLockTableWait()? Does whatever mechanism you have in mind not have
race conditions?
--
Peter Geoghegan
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