diff --git a/etiquette/constants.py b/etiquette/constants.py
index 4d6b5e8..548034e 100644
--- a/etiquette/constants.py
+++ b/etiquette/constants.py
@@ -42,7 +42,7 @@ FILENAME_BADCHARS = '\\/:*?<>|"'
 # Note: Setting user_version pragma in init sequence is safe because it only
 # happens after the out-of-date check occurs, so no chance of accidentally
 # overwriting it.
-DATABASE_VERSION = 11
+DATABASE_VERSION = 12
 DB_INIT = '''
 PRAGMA cache_size = 10000;
 PRAGMA count_changes = OFF;
@@ -161,6 +161,7 @@ CREATE TABLE IF NOT EXISTS photo_tag_rel(
 );
 CREATE INDEX IF NOT EXISTS index_photo_tag_rel_photoid on photo_tag_rel(photoid);
 CREATE INDEX IF NOT EXISTS index_photo_tag_rel_tagid on photo_tag_rel(tagid);
+CREATE INDEX IF NOT EXISTS index_photo_tag_rel_photoid_tagid on photo_tag_rel(photoid, tagid);
 ----------------------------------------------------------------------------------------------------
 CREATE TABLE IF NOT EXISTS tag_group_rel(
     parentid TEXT NOT NULL,
diff --git a/utilities/database_upgrader/database_upgrader.py b/utilities/database_upgrader/database_upgrader.py
index 0e420da..32f6c8e 100644
--- a/utilities/database_upgrader/database_upgrader.py
+++ b/utilities/database_upgrader/database_upgrader.py
@@ -227,6 +227,17 @@ def upgrade_10_to_11(photodb):
 
     cur.execute('PRAGMA foreign_keys = ON')
 
+def upgrade_11_to_12(photodb):
+    '''
+    Added multicolumn (photoid, tagid) index to the photo_tag_rel table to
+    improve the speed of individual relation searching, important for the
+    new intersection-based search.
+    '''
+    query = '''
+    CREATE INDEX IF NOT EXISTS index_photo_tag_rel_photoid_tagid on photo_tag_rel(photoid, tagid)
+    '''
+    photodb.sql.cursor().execute(query)
+
 def upgrade_all(data_directory):
     '''
     Given the directory containing a phototagger database, apply all of the