refactor: Optimise landing page performance (#461)

* refactor: Mark all datasets as browsable

* refactor: Optimise count by using estimate

* chore: Move estimate_count function to query.py

* revert: "chore: Move estimate_count function to query.py"

ref: cc28c65

* revert: "refactor: Optimise count by using estimate"

ref: 46b5d1d

* refactor: Remove query for getting row count of api_ref_data

main/templates/browse/home.html

@@ -40,8 +40,8 @@
  <div class="{% include "_side_block_classes.html" %} md:row-span-3">
  <p class="text-xs m-4">
  {% if browsable_datasets %}
- {{ total_indexed_human }} bibliographic&nbsp;items
- now indexed among&nbsp;sources:
+ Bibliographic&nbsp;items
+ are indexed among&nbsp;sources:
  {% for ds_id in browsable_datasets %}
  <a class="{% if dataset_id == ds_id %}font-bold{% endif %}" href="{% url "browse_dataset" ds_id %}"
  >{{ ds_id }}</a>{% if not forloop.last %}, {% endif %}

main/views.py

@@ -56,28 +56,9 @@ def home(request):
 
  metrics.gui_home_page_hits.inc()
 
- non_empty_datasets = (
- RefData.objects.values_list('dataset', flat=True).
- distinct())
-
- total_indexed_citations = RefData.objects.count()
- units = ('', 'k', 'M', 'G', 'T', 'P')
- factor = 1000.0
- magnitude = int(floor(log_(max(abs(total_indexed_citations), 1), factor)))
- total_indexed_human = '%.2f%s' % (
- total_indexed_citations / factor**magnitude,
- units[magnitude],
- )
-
- browsable_datasets = [
- ds_id
- for ds_id in settings.RELATON_DATASETS
- if ds_id in non_empty_datasets]
-
  return render(request, 'browse/home.html', dict(
  **shared_context,
- total_indexed_human=total_indexed_human,
- browsable_datasets=browsable_datasets,
+ browsable_datasets=settings.RELATON_DATASETS,
  ))