Added instructions for re-applying automatic tags to corpus.

This is especially useful when upgrading notmuch versions.

diff --git a/howto.mdwn b/howto.mdwn
index f0673087f3cfb474c07dd5d90b8b187455c9b333..0e75acc82bdc4b2aee8f9e957c6e8047a90d07a7 100644 (file)
--- a/howto.mdwn
+++ b/howto.mdwn
@@ -97,3 +97,20 @@ various "third party" notmuch utilities.
   [available](http://git.upsilon.cc/cgi-bin/gitweb.cgi?p=zack-homepage.git;a=history;f=blog/posts/2011/01/how_to_use_Notmuch_with_Mutt.mdwn)
   in markdown syntax from the Git repository of my homepage.)</small>
 
+* <span id="reapply_auto">**Automatically retagging the database (e.g., when upgrading versions)**</span>
+
+  Certain versions of notmuch include new automatic tags (for example, between
+  0.3 and 0.10, automatic tagging of signed and encrypted messages was added).
+  However, for users running with databases created in older versions of
+  notmuch, these tags are missing in pre-existing messages and need to be
+  added.  One way to do this is as follows:
+
+                           $ notmuch dump ~/out.nm
+                           $ mv ~/Mail/.notmuch ~/.notmuch.bak
+                           $ notmuch new
+                           $ notmuch tag -inbox -unread '*'
+                           $ notmuch restore --accumulate ~/out.nm
+
+  At this point, one should run a sanity check on the tags, and if everything
+  has merged correctly, the ~/.notmuch.bak directory is expendable, as is
+  ~/out.nm.