[PATCH 3/3] SearchIdx: Allow the amount of indexing be configured

["Eric W. Biederman" <ebiederm@xmission.com>]

This adds a new inbox configuration option 'indexlevel' that can take
the values 'positions', 'terms', and 'over'.

When set to 'positions' everything is indexed including the positions
of all terms.

When set to 'terms' everything except the positions of terms is
indexed.

When set to 'over' terms and positions are not indexed.  Just the
Overview database for NNTP is created.  Which is still quite good and
allows searching for messages by Message-ID.  But there are no indexes to support
searching inside the email messages themselves.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 lib/PublicInbox/Config.pm    | 2 +-
 lib/PublicInbox/SearchIdx.pm | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index 289c36a6ccf1..78586560cf0f 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -158,7 +158,7 @@ sub _fill {
 
 	foreach my $k (qw(mainrepo filter url newsgroup
 			infourl watch watchheader httpbackendmax
-			replyto feedmax nntpserver)) {
+			replyto feedmax nntpserver indexlevel)) {
 		my $v = $self->{"$pfx.$k"};
 		$rv->{$k} = $v if defined $v;
 	}
diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm
index deb87db3f88a..c42821f813a7 100644
--- a/lib/PublicInbox/SearchIdx.pm
+++ b/lib/PublicInbox/SearchIdx.pm
@@ -47,6 +47,7 @@ sub git_unquote ($) {
 
 sub new {
 	my ($class, $ibx, $creat, $part) = @_;
+	my $levels = qr/(positions|terms|over)/;
 	my $mainrepo = $ibx; # for "public-inbox-index" w/o entry in config
 	my $git_dir = $mainrepo;
 	my ($altid, $git);
@@ -62,6 +63,13 @@ sub new {
 				PublicInbox::AltId->new($ibx, $_);
 			} @$altid ];
 		}
+		if ($ibx->{indexlevel}) {
+			if ($ibx->{indexlevel} =~ $levels) {
+				$indexlevel = $ibx->{indexlevel};
+			} else {
+				die("Invalid indexlevel $ibx->{indexlevel}\n");
+			}
+		}
 	} else { # v1
 		$ibx = { mainrepo => $git_dir, version => 1 };
 	}
-- 
2.17.1