searchenginetracker: Optimize direct/recursive folder lookups

tracker:uri-is-descendant/parent has the unfortunate side effect of
rendering the collation mechanisms in the database useless, so those
require full table scans to be validated.

Performing these as pure string comparisons will perform much better,
as those allow the underlying sqlite to rely on its own collation
to perform the search, which can be significantly faster with many
elements in the database.

https://bugzilla.gnome.org/show_bug.cgi?id=758407

diff --git a/gtk/gtksearchenginetracker.c b/gtk/gtksearchenginetracker.c
index 31da5089ce34fc2cb329b96f8f28d21fdec05306..02e74085aae2a028619ea572ba5da04413c74e0c 100644 (file)
--- a/gtk/gtksearchenginetracker.c
+++ b/gtk/gtksearchenginetracker.c
@@ -227,7 +227,8 @@ sparql_escape_string (const gchar *literal)
 static void
 sparql_append_string_literal (GString     *sparql,
                               const gchar *str,
-                              gboolean     glob)
+                              gboolean     glob,
+                              gboolean     is_dir_uri)
 {
   gchar *s;
 
@@ -236,6 +237,8 @@ sparql_append_string_literal (GString     *sparql,
   g_string_append_c (sparql, '"');
   g_string_append (sparql, s);
 
+  if (is_dir_uri)
+    g_string_append_c (sparql, '/');
   if (glob)
     g_string_append_c (sparql, '*');
   g_string_append_c (sparql, '"');
@@ -250,7 +253,7 @@ sparql_append_string_literal_lower_case (GString     *sparql,
   gchar *s;
 
   s = g_utf8_strdown (str, -1);
-  sparql_append_string_literal (sparql, s, FALSE);
+  sparql_append_string_literal (sparql, s, FALSE, FALSE);
   g_free (s);
 }
 
@@ -347,11 +350,12 @@ gtk_search_engine_tracker_start (GtkSearchEngine *engine)
                          "WHERE {"
                          "  ?urn a nfo:FileDataObject ;"
                          "  tracker:available true ; ");
+                         "  nfo:belongsToContainer ?parent; ");
 
 #ifdef FTS_MATCHING
   /* Using FTS: */
   g_string_append (sparql, "fts:match ");
-  sparql_append_string_literal (sparql, search_text, TRUE);
+  sparql_append_string_literal (sparql, search_text, TRUE, FALSE);
 #endif
 
   g_string_append (sparql, ". FILTER (BOUND(nie:url(?urn)) && ");
@@ -365,11 +369,16 @@ gtk_search_engine_tracker_start (GtkSearchEngine *engine)
       gchar *location_uri = g_file_get_uri (location);
       g_string_append (sparql, " && ");
       if (recursive)
-        g_string_append (sparql, "tracker:uri-is-descendant(");
+        {
+          g_string_append (sparql, "fn:starts-with(nie:url(?urn),");
+          sparql_append_string_literal (sparql, location_uri, FALSE, TRUE);
+          g_string_append (sparql, ")");
+        }
       else
-        g_string_append (sparql, "tracker:uri-is-parent(");
-      sparql_append_string_literal (sparql, location_uri, FALSE);
-      g_string_append (sparql, ",nie:url(?urn))");
+        {
+          g_string_append (sparql, "nie:url(?parent) = ");
+          sparql_append_string_literal (sparql, location_uri, FALSE, FALSE);
+        }
       g_free (location_uri);
     }