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

Re: HOT updates & REDIRECT line pointers

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: HOT updates & REDIRECT line pointers
Date: 2012-03-22 13:31:57
Message-ID: CA+U5nMKBN_GKoN41nRq_MbNe0ch24Bbcy0H83npyw5XypzSBpQ@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, Mar 22, 2012 at 1:28 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Wed, Mar 21, 2012 at 9:22 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> It strikes me that it likely wouldn't be any
>>> worse than, oh, say, flipping the default value of
>>> standard_conforming_strings,
>>
>> Really?  It's taking away functionality and not supplying any substitute
>> (or at least you did not propose any).  In fact, you didn't even suggest
>> exactly how you propose to not break joined UPDATE/DELETE.
>
> Oh, hmm, interesting.  I had been thinking that you were talking about
> a case where *user code* was relying on the semantics of the TID,
> which has always struck me as an implementation detail that users
> probably shouldn't get too attached to.  But now I see that you're
> talking about something much more basic - the fundamental
> implementation of UPDATE and DELETE relies on the TID not changing
> under them.  That pretty much kills this idea dead in the water.

Surely it just stops you using that idea 100% of the time. I don't see
why you can't have this co-exist with the current mechanism. So it
doesn't kill it for the common case.

But would the idea deliver much value? Is line pointer bloat a
problem? (I have no idea if it is/is not)

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

In response to

Responses

pgsql-hackers by date

Next:From: Merlin MoncureDate: 2012-03-22 13:35:30
Subject: Re: HOT updates & REDIRECT line pointers
Previous:From: Robert HaasDate: 2012-03-22 13:07:05
Subject: Re: checkpoint patches

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