Skip site navigation (1) Skip section navigation (2)

Re: Bug in autovacuum.c?

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Bruce Momjian <bruce(at)momjian(dot)us>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Bug in autovacuum.c?
Date: 2011-04-01 16:14:18
Message-ID: AANLkTin1RdHLRQ7Q_ZWysCGz8YmbEVeiP78wH0T-yxtc@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Fri, Apr 1, 2011 at 11:18 AM, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> Robert Haas wrote:
>> Oh, quite right.  Sorry I missed that.  I suppose if we wanted to fix
>> this for real, we'd want to get:
>>
>> 105->5
>> 104->4
>> 103->3
>> 102->max_xid
>> 101->max_xid-1
>> 100->max_xid-2
>> 99->max_xid-3
>> 98->max_xid-4
>>
>> But it doesn't seem worth getting excited about.
>
> I think (?) the problem with that is the every time you wrap around you
> get more out of sync.  :-O

It's not clear to me that it matters a bit, though.

> Thinking more, the problem is that when the xid counter wraps around
> from max_xid to 3, we jump the freeze horizon by three, e.g 5000 to
> 5003.  So when, the freeze horizon wraps, we can either have that jump
> by three, e.g set it to FirstNormalTransactionId, or delay by three,
> e.g. set it to MaxTransactionId.

So what?  :-)

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

In response to

Responses

pgsql-hackers by date

Next:From: Merlin MoncureDate: 2011-04-01 16:43:14
Subject: Re: Process local hint bit cache
Previous:From: Thom BrownDate: 2011-04-01 15:57:11
Subject: Re: pgsql: Support comments on FOREIGN DATA WRAPPER and SERVER objects.

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group