Improve performance of the solr query used to generate the advanced s…

…earch form

Running this locally against the production solr sped the solr query up from
a median 10,691 ms to a median 1,851 ms.

This removes several potentially expensive parameters from the solr query we
send to generate the advanced search page:
* facet.query
* facet.pivot
* stats
* stats.field
* facet.field, except for the facet field values we need to retrieve to render
  the advanced search form

app/controllers/catalog_controller.rb

@@ -874,4 +874,8 @@ def search_service_compatibility_wrapper
     def solrize_boolean_params
       @search_state = search_state.reset(AdvancedBooleanOperators.new(search_state.params).for_boolqparser)
     end
+
+    def blacklight_advanced_search_form_params
+      params.select { |key, _value| key == 'action' }
+    end
 end

app/models/advanced_form_search_builder.rb

@@ -2,7 +2,7 @@
 # This class is responsible for building a solr query
 # that renders an advanced search form
 class AdvancedFormSearchBuilder < SearchBuilder
-  self.default_processor_chain += %i[do_not_limit_languages]
+  self.default_processor_chain += %i[do_not_limit_languages only_request_advanced_facets]
 
   def do_not_limit_languages(solr_params)
     solr_params.update(solr_params) do |key, value|
@@ -13,4 +13,11 @@ def do_not_limit_languages(solr_params)
       end
     end
   end
+
+  def only_request_advanced_facets(solr_params)
+    return unless blacklight_params[:action] == 'advanced_search'
+
+    solr_params['facet.field'] = blacklight_config.facet_fields.values.select(&:include_in_advanced_search).map(&:key)
+    %w[facet.pivot facet.query stats stats.field].each { |unneeded_field| solr_params.delete unneeded_field }
+  end
 end

spec/models/advanced_form_search_builder_spec.rb

@@ -29,4 +29,54 @@
       end.not_to(change { solr_params })
     end
   end
+
+  describe '#only_request_advanced_facets' do
+    let(:blacklight_config) { CatalogController.blacklight_config }
+
+    it 'does not modify anything if the action is numismatics' do
+      builder.with({ action: 'numismatics' })
+      solr_params = { "facet.field" => %w[issue_metal_s issue_city_s] }
+      expect do
+        builder.only_request_advanced_facets(solr_params)
+      end.not_to(change { solr_params })
+    end
+
+    it 'removes unnecessary facet.field entries if the action is advanced_search' do
+      builder.with({ action: 'advanced_search' })
+      solr_params = { "facet.field" => %w[genre_facet subject_era_facet geographic_facet] }
+
+      builder.only_request_advanced_facets(solr_params)
+
+      expect(solr_params['facet.field']).not_to include 'genre_facet'
+      expect(solr_params['facet.field']).not_to include 'subject_era_facet'
+      expect(solr_params['facet.field']).not_to include 'geographic_facet'
+    end
+
+    it 'adds the needed facet.field entries if the action is advanced_search' do
+      builder.with({ action: 'advanced_search' })
+      solr_params = { "facet.field" => %w[genre_facet subject_era_facet geographic_facet] }
+
+      builder.only_request_advanced_facets(solr_params)
+
+      expect(solr_params['facet.field']).to include 'language_facet'
+    end
+
+    it 'removes unneeded params if the action is advanced_search' do
+      builder.with({ action: 'advanced_search' })
+      solr_params = {
+        "facet.pivot" => %w[lc_1letter_facet lc_rest_facet],
+        "facet.query" => ['cataloged_tdt:[NOW/DAY-7DAYS TO NOW/DAY+1DAY]', 'cataloged_tdt:[NOW/DAY-14DAYS TO NOW/DAY+1DAY]'],
+        "stats" => true,
+        "stats.field" => "pub_date_start_sort"
+      }
+
+      builder.only_request_advanced_facets(solr_params)
+
+      expect(solr_params.keys).not_to include 'facet.query'
+      expect(solr_params.keys).not_to include 'facet.pivot'
+      expect(solr_params.keys).not_to include 'stats'
+      expect(solr_params.keys).not_to include 'stats.field'
+      expect(solr_params.keys).to include 'facet.field'
+    end
+  end
 end

spec/requests/advanced_search_spec.rb

@@ -2,6 +2,12 @@
 
 require 'rails_helper'
 
+RSpec::Matchers.define :request_without_facet_queries do
+  match do |actual|
+    actual[:params].keys.exclude? 'facet.query'
+  end
+end
+
 describe 'Orangelight advanced search', type: :request, advanced_search: true do
   before do
     stub_holding_locations
@@ -11,4 +17,15 @@
     get '/advanced?f[subject_facet][]=United+Nations-Decision+making'
     expect(response.status).to eq(200)
   end
+
+  it 'does not send complex facet queries to solr when rendering advanced search form' do
+    # rubocop:disable RSpec/AnyInstance
+    expect_any_instance_of(RSolr::Client).to receive(:send_and_receive)
+      .with('select', request_without_facet_queries)
+      .once
+      .and_call_original
+    # rubocop:enable RSpec/AnyInstance
+
+    get '/advanced'
+  end
 end