[tracker/wip/carlosg/update-perf: 33/43] core: Optimize deletion of classes of a resource

[Carlos Garnacho <carlosg src gnome org>]

commit 0c1b057c9eee6f3a95b4b9b93068050fd37847f6
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Aug 19 18:09:25 2022 +0200

    core: Optimize deletion of classes of a resource
    
    Currently the code is exceedengly thorough and issues individual deletes
    for every property that is related to the class being deleted. We can take
    some shortcuts here, and avoid querying existing values for most cases,
    only 2 cases remain where it is necessary to fetch the previous content:
    
    - Properties that have TRACKER_PROPERTY_TYPE_RESOURCE, in order to correctly
      change the refcounting of the resource that the property points to.
    - Properties that are domain indexes in other classes, since we have to
      chain up to those tables with the right value being deleted.
    
    All other situations can do without fetching the previous values for the
    property, and for single valued properties, they can even be delegated to
    the deletion of the row in the table representing the TrackerClass.
    
    The result is a speedup while deleting entire resources.

 src/libtracker-sparql/core/tracker-data-update.c | 69 ++++++++++++++----------
 1 file changed, 42 insertions(+), 27 deletions(-)
---
diff --git a/src/libtracker-sparql/core/tracker-data-update.c 
b/src/libtracker-sparql/core/tracker-data-update.c
index 36eb427bc..18da62913 100644
--- a/src/libtracker-sparql/core/tracker-data-update.c
+++ b/src/libtracker-sparql/core/tracker-data-update.c
@@ -2309,14 +2309,21 @@ cache_delete_resource_type_full (TrackerData   *data,
                }
        }
 
-       /* delete all property values */
-
+       /* Delete property values, only properties that:
+        * - Have ?prop rdfs:range rdfs:Resource
+        * - Are domain indexes in other classes
+        *
+        * Do need inspection of the previous content. All multivalued properties
+        * can be cleared through TRACKER_LOG_MULTIVALUED_PROPERTY_CLEAR, and all
+        * values for other single-valued properties will eventually disappear when
+        * deleting the row from the table representing the given TrackerClass.
+        */
        properties = tracker_ontologies_get_properties (ontologies, &n_props);
 
        for (p = 0; p < n_props; p++) {
-               gboolean            multiple_values;
+               gboolean multiple_values;
                GArray *old_values;
-               gint                y;
+               gint y;
 
                prop = properties[p];
 
@@ -2329,37 +2336,45 @@ cache_delete_resource_type_full (TrackerData   *data,
 
                maybe_append_fts_property (data, prop);
 
-               old_values = get_property_values (data, prop, error);
-               if (!old_values)
-                       return FALSE;
+               if (*tracker_property_get_domain_indexes (prop) ||
+                   tracker_property_get_data_type (prop) == TRACKER_PROPERTY_TYPE_RESOURCE) {
+                       old_values = get_property_values (data, prop, error);
+                       if (!old_values)
+                               return FALSE;
 
-               for (y = old_values->len - 1; y >= 0 ; y--) {
-                       GValue *old_gvalue, copy = G_VALUE_INIT;
+                       for (y = old_values->len - 1; y >= 0 ; y--) {
+                               GValue *old_gvalue, copy = G_VALUE_INIT;
 
-                       old_gvalue = &g_array_index (old_values, GValue, y);
-                       g_value_init (&copy, G_VALUE_TYPE (old_gvalue));
-                       g_value_copy (old_gvalue, &copy);
+                               old_gvalue = &g_array_index (old_values, GValue, y);
+                               g_value_init (&copy, G_VALUE_TYPE (old_gvalue));
+                               g_value_copy (old_gvalue, &copy);
 
-                       value_set_remove_value (old_values, old_gvalue);
+                               value_set_remove_value (old_values, old_gvalue);
 
-                       if (multiple_values) {
-                               log_entry_for_multi_value_property (data,
-                                                                   TRACKER_LOG_MULTIVALUED_PROPERTY_DELETE,
-                                                                   prop, &copy);
-                       } else {
-                               log_entry_for_single_value_property (data,
-                                                                    tracker_property_get_domain (prop),
-                                                                    prop, NULL);
-                       }
+                               if (!multiple_values) {
+                                       log_entry_for_single_value_property (data,
+                                                                            tracker_property_get_domain 
(prop),
+                                                                            prop, NULL);
+                               }
 
-                       if (tracker_property_get_data_type (prop) == TRACKER_PROPERTY_TYPE_RESOURCE)
-                               tracker_data_resource_unref (data, g_value_get_int64 (&copy), 
multiple_values);
+                               if (tracker_property_get_data_type (prop) == TRACKER_PROPERTY_TYPE_RESOURCE)
+                                       tracker_data_resource_unref (data, g_value_get_int64 (&copy), 
multiple_values);
 
-                       if (!multiple_values)
-                               delete_property_domain_indexes (data, prop, &copy);
+                               if (!multiple_values)
+                                       delete_property_domain_indexes (data, prop, &copy);
 
-                       g_value_unset (&copy);
+                               g_value_unset (&copy);
+                       }
                }
+
+               if (multiple_values) {
+                       log_entry_for_multi_value_property (data,
+                                                           TRACKER_LOG_MULTIVALUED_PROPERTY_CLEAR,
+                                                           prop, NULL);
+               }
+
+               if (data->resource_buffer->predicates)
+                       g_hash_table_remove (data->resource_buffer->predicates, prop);
        }
 
        g_value_init (&gvalue, G_TYPE_INT64);