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Re: Notes on lock table spilling

From: Greg Stark <gsstark(at)mit(dot)edu>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Notes on lock table spilling
Date: 2005-04-05 03:32:47
Message-ID: 87acodq4o0.fsf@stark.xeocode.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> writes:

> Using Phantom Xids
> ==================
> The idea here is to use an approach similar to what we use now: mark the
> tuples with an Xid when it is locked.  A phantom Xid is a sort-of Xid,
> with multiple real Xids associated to it.  So we mark the tuple with the
> regular Xid the first time the share lock is acquired; if a second
> transaction wants to lock the tuple, it creates a new phantom Xid which
> "contains" the original Xid in the tuple and its own Xid, insert it into
> the phantom Xid table, and mark the tuple with that as Xmax.

That sounds like a fancy way to describe "make a linked list of lockers".

-- 
greg


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