Notmuch claims to commit changes made before an open transaction on
close but actually throws them away (according to the documentation).

According to the notmuch documentation,

> For writable databases, notmuch_database_close commits all changes
> to disk before closing the database.  If the caller is currently in
> an atomic section (there was a notmuch_database_begin_atomic
> without a matching notmuch_database_end_atomic), this will discard
> changes made in that atomic section (but still commit changes made
> prior to entering the atomic section).

However, this isn't true. Notmuch atomic transactions don't flush on
entry so, this comment from the xapian documentation applies:

> If you're applying atomic groups of changes and only wish to ensure
> that each group is either applied or not applied, then you can prevent
> the automatic commit() before and after the transaction by starting
> the transaction with begin_transaction(false). However, if
> cancel_transaction is called (or if commit_transaction isn't called
> before the WritableDatabase object is destroyed) then any changes
> which were pending before the transaction began will also be
> discarded.

source: http://xapian.org/docs/apidoc/html/classXapian_1_1WritableDatabase.html

This means that, in theory at least, xapian could throw away *all*
changes to the database if a transaction is open.

-- 
Steven Allen
(310) 433-5865
((Do Not Email <honeypot@stebalien.com>))