Re: [HACKERS] Unlogged tables cleanup

Hi,

On 2019-05-13 13:33:00 -0400, Alvaro Herrera wrote:
> On 2019-May-13, Andres Freund wrote:
> 
> > On 2019-05-13 13:07:30 -0400, Alvaro Herrera wrote:
> > > On 2019-May-13, Andres Freund wrote:
> 
> > > The first ResetUnloggedRelations call occurs before any WAL is replayed,
> > > so the data dir certainly still in inconsistent state.  At that point,
> > > we need the init fork files to be present, because the init files are the
> > > indicators of what relations we need to delete the other forks for.
> > 
> > Hm. I think this might be a self-made problem. For the main fork, we
> > don't need this - if the init fork was created before the last
> > checkpoint/restartpoint, it'll be on-disk. If it was created afterwards,
> > WAL replay will recreate both main an init fork. So the problem is just
> > that the VM fork might survive, because it'll not get nuked given the
> > current arrangement. Is that what you're thinking about?

I was wrong here - I thought we WAL logged the main fork creation even
for unlogged tables. I think it's foolish that we don't, but we don't.

Greetings,

Andres Freund