Transitioning notmuch/Xapian from 32-bit to 64-bit system

[Olly Betts]

On Tue, Jul 09, 2019 at 01:28:51PM -0300, David Bremner wrote:
> Thomas Schwinge <thomas at schwinge.name> writes:
> 
> > sizes?).  Doing some light (read-only!) testing, it seems to work fine to
> > access the old 32-bit built Xapian "chert" database with 64-bit
> > notmuch/Xapian.  Is that (a) generally safe and expected to work fine,
> > (b) there may be issues, or (c) don't do that, or don't know?
> 
> IIRC, Olly previously confirmed that the Xapian database is architecture
> independent.

Yes.

[...]
> 
> > (Of course, I'll eventually want to rebuild the database, to take
> > advantage of several new features both on the notmuch and Xapian sides,
> > but I'd prefer to do that later.)
> >
> 
> It would be wise to make a backup with "notmuch dump" before going much further.

You can convert the database at the Xapian level:

https://getting-started-with-xapian.readthedocs.io/en/latest/advanced/admin_notes.html#converting-a-chert-database-to-a-glass-database

However that probably doesn't allow taking advantage of all the new
notmuch features, so it's probably better to dump the tags, reindex
then restore the tags.

Cheers,
    Olly