Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updatedtuple - Mailing list pgsql-committers

From Andres Freund
Subject Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updatedtuple
Date
Msg-id 20171206080319.v7of3p45yvapkgla@alap3.anarazel.de
Whole thread Raw
In response to Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updatedtuple  (Andres Freund <andres@anarazel.de>)
Responses Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple  (Michael Paquier <michael.paquier@gmail.com>)
Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple  (Michael Paquier <michael.paquier@gmail.com>)
List pgsql-committers
On 2017-11-20 11:18:45 -0800, Andres Freund wrote:
> Hi,
> 
> On 2017-11-13 19:03:41 -0800, Andres Freund wrote:
> > Hi,
> > 
> > On 2017-11-03 07:53:30 -0700, Andres Freund wrote:
> > > Here's that patch.  I've stared at this some, and Robert did too. Robert
> > > mentioned that the commit message might need some polish and I'm not
> > > 100% sure about the error message texts yet.
> > > 
> > > I'm not yet convinced that the new elog in vacuumlazy can never trigger
> > > - but I also don't think we want to actually freeze the tuple in that
> > > case.
> > 
> > I'm fairly sure it could be triggered, therefore I've rewritten that.
> > 
> > I've played around quite some with the attached patch. So far, after
> > applying the second patch, neither VACUUM nor VACUUM FULL / CLUSTER make
> > the situation worse for already existing corruption. HOT pruning can
> > change the exact appearance of existing corruption a bit, but I don't
> > think it can make the corruption meaningfully worse.  It's a bit
> > annoying and scary to add so many checks to backbranches but it kinda
> > seems required.  The error message texts aren't perfect, but these are
> > "should never be hit" type elog()s so I'm not too worried about that.
> > 
> > 
> > Please review!
> 
> Ping? Alvaro, it'd be good to get some input here.

Ping.  I'm a bit surprised that a bug fixing a significant data
corruption issue has gotten no reviews at all.

Greetings,

Andres Freund


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