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

Re: Duplicate values found when reindexing unique index

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Gregory Stark <stark(at)enterprisedb(dot)com>, Mason Hale <masonhale(at)gmail(dot)com>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: Duplicate values found when reindexing unique index
Date: 2007-12-31 14:31:16
Message-ID: 1199111476.9558.157.camel@ebony.site (view raw or flat)
Thread:
Lists: pgsql-bugs
On Mon, 2007-12-31 at 01:27 -0500, Tom Lane wrote:
> Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> > "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> >> I wonder whether it's just a coincidence that these have the same offset
> >> number...
> 
> > I can't imagine any Postgres bug which would depend on the offsets
> > being the same. But what I could imagine is filesystem corruption
> > which copied the block to someplace else in the table or possibly has
> > even mapped the same block into two different places in the table.
> 
> That idea was in my mind too, but Mason stated that the rows showed
> different "updated_at" values, so they couldn't be mirror images of that
> sort.  

Tom, 

I think you misread Mason's post of 20:23 GMT-6 where he says the
created_at values are the *same*, not different. Mason's previous bug
report 3724 also had duplicate rows with matching created_at values.

So mangling block numbers and re-writing blocks in the wrong place is a
possibility. Filesystem corruption is just one way that can occur.

-- 
  Simon Riggs
  2ndQuadrant  http://www.2ndQuadrant.com


In response to

Responses

pgsql-bugs by date

Next:From: Mason HaleDate: 2007-12-31 14:43:09
Subject: Re: Duplicate values found when reindexing unique index
Previous:From: Tom LaneDate: 2007-12-31 06:27:51
Subject: Re: Duplicate values found when reindexing unique index

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