Introduce index on `project_fingerprint`

db/migrate/20201110035029_created_index_for_vulnerability_occurrences_on_project_fingerprint.rb

+# frozen_string_literal: true
+
+class CreatedIndexForVulnerabilityOccurrencesOnProjectFingerprint < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_vulnerability_occurrences_on_project_fingerprint'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :vulnerability_occurrences, :project_fingerprint, name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name :vulnerability_occurrences, INDEX_NAME
+  end
+end

db/schema_migrations/20201110035029

+21245809e056dfefedc4d2c6a8e2bf642bfcee480a863f8707ba6fa6b748a2e0
\ No newline at end of file

db/structure.sql

@@ -22130,6 +22130,8 @@ CREATE INDEX index_vulnerability_occurrences_for_issue_links_migration ON vulner
 
 CREATE INDEX index_vulnerability_occurrences_on_primary_identifier_id ON vulnerability_occurrences USING btree (primary_identifier_id);
 
+CREATE INDEX index_vulnerability_occurrences_on_project_fingerprint ON vulnerability_occurrences USING btree (project_fingerprint);
+
 CREATE INDEX index_vulnerability_occurrences_on_scanner_id ON vulnerability_occurrences USING btree (scanner_id);
 
 CREATE UNIQUE INDEX index_vulnerability_occurrences_on_unique_keys ON vulnerability_occurrences USING btree (project_id, primary_identifier_id, location_fingerprint, scanner_id);