Re: hung backends stuck in spinlock heavy endless loop

On 01/15/2015 03:23 AM, Peter Geoghegan wrote:
> So now the question is: how did that inconsistency arise? It didn't
> necessarily arise at the time of the (presumed) split of block 2 to
> create 9. It could be that the opaque area was changed by something
> else, some time later. I'll investigate more.

Merlin, could you re-run the test with a WAL archive (if you don't have 
one already), and then run pg_xlogdump, filtering it to show only the 
changes to the index? That should show us how the index got to be the 
way it is. Also, if you could post a copy of the raw relation file for 
pg_class_oid_index; I assume it's not too large.

Something like:

pg_xlogdump -r Btree -p walarchive/ -s 0/20035D0 | grep 11917

11917 is the relfilenode of pg_class_oid_index on a freshly initdb'd 
cluster. In case it's not the same on your system, you can use oid2name 
to find it out.

- Heikki