refactor(be): remove coalesce when ordering events list

A coalesce when ordering the list of events was causing MySQL to ignore
the timestamp index, resulting in a slower query execution time. Removed
the coalesce in favor of jordering by just the timestamp field

Author: luis-dk

common/entities/event.py

@@ -44,10 +44,6 @@ class EventEntity(BaseEntity):
     instance_set = ForeignKeyField(InstanceSet, null=True, backref="events", on_delete="SET NULL")
     v2_payload = JSONField(null=False)
 
-    @classmethod
-    def timestamp_coalesce(cls) -> Node:
-        return fn.COALESCE(cls.timestamp, cls.created_timestamp)
-
     @property
     def components(self) -> list[Component]:
         return [self.component] if self.component else []

common/entity_services/event_service.py

@@ -54,15 +54,15 @@ def get_events_with_rules(*, rules: ListRules, filters: ProjectEventFilters) ->
             filter_list.append(EventEntity.task << filters.task_ids)
         if filters.date_range_start:
             filter_list.append(
-                EventEntity.timestamp_coalesce() >= EventEntity.timestamp.db_value(filters.date_range_start)
+                EventEntity.timestamp >= EventEntity.timestamp.db_value(filters.date_range_start)
             )
         if filters.date_range_end:
             filter_list.append(
-                EventEntity.timestamp_coalesce() < EventEntity.timestamp.db_value(filters.date_range_end)
+                EventEntity.timestamp < EventEntity.timestamp.db_value(filters.date_range_end)
             )
 
         query = query.where(*filter_list)
-        page = Page[EventEntity].get_paginated_results(query, EventEntity.timestamp_coalesce(), rules)
+        page = Page[EventEntity].get_paginated_results(query, EventEntity.timestamp, rules)
 
         # Using a single query to fetch the Instance and Journey data
         instance_set_ids = {e.instance_set_id for e in page.results}