Re: Adding REPACK [concurrently]

Hello, Antonin!

On Sat, Dec 13, 2025 at 8:39 PM Antonin Houska <ah(at)cybertec(dot)at> wrote:
> > ---
> > > SpinLockAcquire(&shared->mutex);
> > > valid = shared->sfs_valid;
> > > SpinLockRelease(&shared->mutex);
> >
> > Better to remember last_exported here to avoid any races/misses.
>
> What races/misses exactly?

Just as some way to reduce a number of potential scenarios/states
between parallel actors.

> > ---
> > > bool done;
> >
> > bool exit_after_lsn_upto?
>
> Not sure.

I think it should be named in some way to signal it is a request, not a report.

> > Also, should we add some kind of back pressure between building
> > indexes/new heap and num of WAL we have?
> > But probably it is out of scope of the patch.
>
> Do you mean that the decoding worker should be less active if the amount of
> WAL doesn't grow too fast?

In the previous version (without background) we have some kind of
back-pressure during the scan part (if we have too muchWAL delayed
because of us - we process it).
But it is not more true with a background worker. At the same time -
it never was during the index building phase...

Best regards,
Mikhail.