miscsearch: a new Xapian sub-DB for extindex

This will be used to index and search Inbox objects and perhaps
individual git repositories/epochs for grokmirror manifest.js.gz
generation.  There is no sharding planned for this at the moment
since inbox count should remain low (~100K to 1M) compared to
message count.

Folding this into the existing sharded DBs could be possible;
but would likely increase query and maintenance costs, as well
as development complexity.  So we'll use a few more inodes and
FDs at runtime, instead.

1 files changed, 3 insertions, 0 deletions

diff --git a/t/extsearch.t b/t/extsearch.t
index 8792fd9e..e28e2f71 100644
--- a/t/extsearch.t
+++ b/t/extsearch.t
@@ -72,4 +72,7 @@ my $es = PublicInbox::ExtSearch->new("$home/eindex");
         isnt($x1->[0], $x2->[0], 'xref3 differs');
 }
 
+my $misc = $es->misc;
+is(scalar($misc->mset('')->items), 2, 'two inboxes');
+
 done_testing;