[tracker/wip/carlosg/test: 6/6] Revert "libtracker-data: Work around terrible query planning from SQLite"

[Carlos Garnacho <carlosg src gnome org>]

commit 2c01aa54307fb1384c2dc5c9d46dd97a4a79c998
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Nov 23 19:33:33 2019 +0100

    Revert "libtracker-data: Work around terrible query planning from SQLite"
    
    This reverts commit 71170665dda8614254728ac99471f1e43e566108.
    
    This is now what happens anyway, although indirectly through a WITH
    subquery. So the optimization is now moot.

 src/libtracker-data/tracker-sparql.c | 59 ------------------------------------
 1 file changed, 59 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 6ab6b14da..559b14d9e 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -6767,65 +6767,6 @@ handle_property_function (TrackerSparql    *sparql,
 {
        TrackerPropertyType type;
 
-       /* As of SQLite 3.26.0, performing an aggregate function (or anything
-        * that requires scanning all results, like distinct) on a unionGraph
-        * view results in full table scans on all unioned selects.
-        *
-        * This quickly gets far too expensive on property functions, as they
-        * are normally used in the SelectClause, so they get to run once per
-        * result. This makes queries like:
-        *
-        * SELECT rdf:type(?u) { ?u a rdfs:Resource }
-        *
-        * prohibitive. The solution is to perform the union inline, and
-        * evaluate the ArgList once on each of the unioned selects. This again
-        * hits table search, and hopefully through an index, so it gets fast
-        * again.
-        */
-       if (tracker_property_get_multiple_values (property) &&
-           tracker_token_is_empty (&sparql->current_state.graph)) {
-               TrackerStringBuilder *str, *old;
-               TrackerParserNode *arg;
-               GHashTable *ht;
-               GHashTableIter iter;
-               gpointer graph;
-
-               arg = _skip_rule (sparql, NAMED_RULE_ArgList);
-
-               _append_string (sparql, "(SELECT GROUP_CONCAT (");
-               str = _append_placeholder (sparql);
-               old = tracker_sparql_swap_builder (sparql, str);
-               _append_string_printf (sparql, "\"%s\"", tracker_property_get_name (property));
-               convert_expression_to_string (sparql, tracker_property_get_data_type (property));
-               tracker_sparql_swap_builder (sparql, old);
-
-               _append_string (sparql, ", ',') ");
-
-               _append_string_printf (sparql, "FROM (SELECT \"%s\" FROM \"main\".\"%s\" WHERE ID = ",
-                                      tracker_property_get_name (property),
-                                      tracker_property_get_table_name (property));
-               if (!_postprocess_rule (sparql, arg, NULL, error))
-                       return FALSE;
-
-               ht = tracker_data_manager_get_graphs (sparql->data_manager);
-               g_hash_table_iter_init (&iter, ht);
-
-               while (g_hash_table_iter_next (&iter, (gpointer *) &graph, NULL)) {
-                       _append_string_printf (sparql, "UNION ALL SELECT \"%s\" FROM \"%s\".\"%s\" WHERE ID = 
",
-                                              tracker_property_get_name (property),
-                                              (gchar *) graph,
-                                              tracker_property_get_table_name (property));
-
-                       if (!_postprocess_rule (sparql, arg, NULL, error))
-                               return FALSE;
-               }
-
-               _append_string (sparql, ")) ");
-
-               sparql->current_state.expression_type = TRACKER_PROPERTY_TYPE_STRING;
-               return TRUE;
-       }
-
        if (tracker_property_get_multiple_values (property)) {
                TrackerStringBuilder *str, *old;