SPARQL: Add tracker:id function

This returns the internal integer ID to be used as last sort key in
queries. This helps retrieving results in stable order which is
important for paged queries.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/libtracker-data/tracker-sparql-expression.vala b/src/libtracker-data/tracker-sparql-expression.vala
index 94adfdada..95b70c49d 100644
--- a/src/libtracker-data/tracker-sparql-expression.vala
+++ b/src/libtracker-data/tracker-sparql-expression.vala
@@ -548,6 +548,13 @@ class Tracker.Sparql.Expression : Object {
 			sql.append_printf ("\"%s_u_offsets\"", v);
 
 			return PropertyType.STRING;
+		} else if (uri == TRACKER_NS + "id") {
+			var type = translate_expression (sql);
+			if (type != PropertyType.RESOURCE) {
+				throw get_error ("expected resource");
+			}
+
+			return PropertyType.INTEGER;
 		} else if (uri == TRACKER_NS + "cartesian-distance") {
 			sql.append ("SparqlCartesianDistance(");
 			translate_expression (sql);