Horton

Re: Bugs in TOAST handling, OID assignment and redo recovery

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: Pavan Deolasee <pavan.deolasee@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-07-23T19:13:15Z
Lists: pgsql-hackers 
On 2018-Apr-11, Peter Eisentraut wrote:

> On 4/10/18 06:29, Pavan Deolasee wrote:
> > One of our 2ndQuadrant support customers recently reported a sudden rush
> > of TOAST errors post a crash recovery, nearly causing an outage. Most
> > errors read like this:
> > 
> > ERROR: unexpected chunk number 0 (expected 1) for toast value nnnn
> 
> While researching this, I found that the terminology in this code is
> quite inconsistent.  It talks about chunks ids, chunk indexes, chunk
> numbers, etc. seemingly interchangeably.  The above error is actually
> about the chunk_seq, not about the chunk_id, as one might think.
> 
> The attached patch is my attempt to clean this up a bit.  Thoughts?

I didn't review your patch carefully, but +1 on the idea.  By all means
let's not forget this for pg12.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Ignore nextOid when replaying an ONLINE checkpoint.

  2. Do not select new object OIDs that match recently-dead entries.