Re: Why copy_relation_data only use wal whenWALarchivingis enabled

On Wed, 2007-10-17 at 18:13 +0100, Heikki Linnakangas wrote:

> > The test script you
> > showed cheats six-ways-from-Sunday to cause an OID collision that would
> > never happen in practice.  The only case where it would really happen
> > is if a table that has existed for a long time (~ 2^32 OID creations)
> > gets dropped and then you're unlucky enough to recycle that exact OID
> > before the next checkpoint --- and then crash before the checkpoint.
> 
> Yeah, it's unlikely to happen, but the consequences are horrible.

When is this going to happen?

We'd need to insert 2^32 toast chunks, which is >4 TB of data, or insert
2^32 large objects, or create 2^32 tables, or any combination of the
above all within one checkpoint duration *and* exactly hit the exact
same relation.

That's a weird and huge application, a very fast server and an unlucky
DBA to hit the exact OID to be reused and then have the server crash so
we'll ever notice.

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