Re: Lazy xid assignment V4

From: Chris Browne <cbbrowne(at)acm(dot)org>
To: pgsql-patches(at)postgresql(dot)org
Subject: Re: Lazy xid assignment V4
Date: 2007-09-04 21:41:20
Message-ID: 60fy1uaz27.fsf@dba2.int.libertyrms.com
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fgp(at)phlo(dot)org ("Florian G. Pflug") writes:
> Pavan Deolasee wrote:
>> On 9/4/07, Florian G. Pflug <fgp(at)phlo(dot)org> wrote:
>>> Hi
>>>
>>> Here is an updated patch, following the discussion.
>>> The patch can be found at: http://soc.phlo.org/lazyxidassign.v4.patch
>>> (I seems I still can't get attachments through to this list)
>>>
>>>
>> I haven't been able to follow the discussions here, but do I need to worry
>> about its interaction with HOT ?
>
> I don't think so. The interactions should be pretty minimal.

Similarly, does it seem likely that Slony-I users would need to worry
about this?

From what I have been seeing, I don't think so, because the
transactions that cause the XIDs to get generated that are of interest
will all be write transactions, and hence exempt from this:

- User transactions that are writing to tables will be exempt :-).

- On an origin node, slon connections that write out SYNC events every
so often are, obviously, write transactions that will again be exempt.

- Transactions that read data from a provider could be affected, as
they are indeed read-only, but their XIDs aren't of interest.

If I speculate right, then there's not much here to worry about. But
best to check... And we'll certainly be testing as this gets
applied...
--
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