Improve performance of follow recommendation scheduler (#16159)

Express follow_recommendations in terms of account_summaries rather than
accounts, integrate filters that are unconditionally used, and materialize
the resulting view.

This should result in the bulk of the computation being performed only once
instead of **once per recommendation language**.

1 files changed, 4 insertions, 2 deletions

diff --git a/app/models/follow_recommendation.rb b/app/models/follow_recommendation.rb
index 6670b6560..1ed6dc49b 100644
--- a/app/models/follow_recommendation.rb
+++ b/app/models/follow_recommendation.rb
@@ -14,9 +14,11 @@ class FollowRecommendation < ApplicationRecord
   belongs_to :account_summary, foreign_key: :account_id
   belongs_to :account, foreign_key: :account_id
 
-  scope :safe, -> { joins(:account_summary).merge(AccountSummary.safe) }
   scope :localized, ->(locale) { joins(:account_summary).merge(AccountSummary.localized(locale)) }
-  scope :filtered, -> { joins(:account_summary).merge(AccountSummary.filtered) }
+
+  def self.refresh
+    Scenic.database.refresh_materialized_view(table_name, concurrently: true, cascade: false)
+  end
 
   def readonly?
     true