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From: Simon Riggs <simon@2ndQuadrant.com>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org, Robert Haas <robertmhaas@gmail.com>
Subject: Re: Small locking bugs in hs
Date: Wed, 20 Jan 2010 14:09:05 +0000
Message-ID: <1263996545.4043.2633.camel@ebony> (raw)
In-Reply-To: <201001201413.09953.andres@anarazel.de>
References: <200912272012.32556.andres@anarazel.de>
	<201001200447.47382.andres@anarazel.de>
	<1263988780.4043.2046.camel@ebony>
	<201001201413.09953.andres@anarazel.de>

On Wed, 2010-01-20 at 14:13 +0100, Andres Freund wrote:
> I do understand it correctly that in CancelVirtualTransaction
> LW_SHARED is 
> taken only so that another transaction can finish during that time?

We're canceling one specific vxid, so no need to block other snapshots
from being taken.

Read only queries don't take ProcArrayLock when they complete and the
Startup process is the only process to record xact completion during
recovery.

-- 
 Simon Riggs           www.2ndQuadrant.com




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