1 files changed, 25 insertions, 11 deletions
diff --git a/activerecord/lib/active_record/collection_cache_key.rb b/activerecord/lib/active_record/collection_cache_key.rb
index 43784b70e3..61581b0451 100644
--- a/activerecord/lib/active_record/collection_cache_key.rb
+++ b/activerecord/lib/active_record/collection_cache_key.rb
@@ -1,23 +1,37 @@
+# frozen_string_literal: true
+
 module ActiveRecord
   module CollectionCacheKey
     def collection_cache_key(collection = all, timestamp_column = :updated_at) # :nodoc:
-      query_signature = Digest::MD5.hexdigest(collection.to_sql)
+      query_signature = ActiveSupport::Digest.hexdigest(collection.to_sql)
       key = "#{collection.model_name.cache_key}/query-#{query_signature}"
 
-      if collection.loaded?
-        size = collection.size
+      if collection.loaded? || collection.distinct_value
+        size = collection.records.size
         if size > 0
-          timestamp = collection.max_by(&timestamp_column).public_send(timestamp_column)
+          timestamp = collection.max_by(&timestamp_column)._read_attribute(timestamp_column)
         end
       else
-        column_type = type_for_attribute(timestamp_column.to_s)
-        column = "#{connection.quote_table_name(collection.table_name)}.#{connection.quote_column_name(timestamp_column)}"
+        if collection.eager_loading?
+          collection = collection.send(:apply_join_dependency)
+        end
+        column_type = type_for_attribute(timestamp_column)
+        column = connection.visitor.compile(collection.arel_attribute(timestamp_column))
+        select_values = "COUNT(*) AS #{connection.quote_column_name("size")}, MAX(%s) AS timestamp"
+
+        if collection.has_limit_or_offset?
+          query = collection.select(column)
+          subquery_alias = "subquery_for_cache_key"
+          subquery_column = "#{subquery_alias}.#{timestamp_column}"
+          subquery = query.arel.as(subquery_alias)
+          arel = Arel::SelectManager.new(subquery).project(select_values % subquery_column)
+        else
+          query = collection.unscope(:order)
+          query.select_values = [select_values % column]
+          arel = query.arel
+        end
 
-        query = collection
-          .unscope(:select)
-          .select("COUNT(*) AS #{connection.quote_column_name("size")}", "MAX(#{column}) AS timestamp")
-          .unscope(:order)
-        result = connection.select_one(query)
+        result = connection.select_one(arel, nil)
 
         if result.blank?
           size = 0