isearch: emulate per-inbox search with ->ALL

Using "eidx_key:" boolean prefix to limit results to a given
inbox, we can use ->ALL to emulate and replace per-Inbox
xap15/[0-9] search indices.

With this change, the presence of "extindex.all.topdir" in the
$PI_CONFIG will cause the WWW code to use that extindex and
ignore per-inbox Xapian DBs in xap15/[0-9].

Unfortunately IMAP search still requires old per-inbox indices,
for now.  Mapping extindex Xapian docids to per-Inbox UIDs and
vice-versa is proving tricky.  Fortunately, IMAP search is
rarely used and optional.  The RFCs don't specify expensive
phrase search, either, so `indexlevel=medium' can be used in
per-inbox Xapian indices to save space.

For primarily WWW (and future JMAP) users; this should result in
significant disk space, FD, and page cache footprint savings for
large instances with many inboxes and many cross-posted
messages.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/WWW.pm b/lib/PublicInbox/WWW.pm
index cdbcff1e..fc208816 100644
--- a/lib/PublicInbox/WWW.pm
+++ b/lib/PublicInbox/WWW.pm
@@ -462,7 +462,7 @@ sub serve_git {
 sub mbox_results {
         my ($ctx) = @_;
         if ($ctx->{env}->{QUERY_STRING} =~ /(?:\A|[&;])q=/) {
-                $ctx->{-inbox}->search or return need($ctx, 'search');
+                $ctx->{-inbox}->isrch or return need($ctx, 'search');
                 require PublicInbox::SearchView;
                 return PublicInbox::SearchView::mbox_results($ctx);
         }