3 files changed, 11 insertions, 8 deletions
diff --git a/activerecord/lib/active_record/relation/batches.rb b/activerecord/lib/active_record/relation/batches.rb
index 46ab67d1cf..ec1176e3dd 100644
--- a/activerecord/lib/active_record/relation/batches.rb
+++ b/activerecord/lib/active_record/relation/batches.rb
@@ -66,11 +66,14 @@ module ActiveRecord
       records = relation.where(table[primary_key].gteq(start)).all
 
       while records.any?
+        records_size = records.size
+        primary_key_offset = records.last.id
+
         yield records
 
-        break if records.size < batch_size
+        break if records_size < batch_size
 
-        if primary_key_offset = records.last.id
+        if primary_key_offset
           records = relation.where(table[primary_key].gt(primary_key_offset)).to_a
         else
           raise "Primary key not included in the custom select clause"
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 422d89060b..8cef4e5554 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -193,8 +193,8 @@ module ActiveRecord
       else
         relation = relation.where(table[primary_key].eq(id)) if id
       end
-
-      connection.select_value(relation.to_sql) ? true : false
+      
+      connection.select_value(relation.to_sql, "#{name} Exists") ? true : false
     end
 
     protected
@@ -243,7 +243,7 @@ module ActiveRecord
     end
 
     def construct_limited_ids_condition(relation)
-      orders = relation.order_values
+      orders = relation.order_values.map { |val| val.presence }.compact
       values = @klass.connection.distinct("#{@klass.connection.quote_table_name table_name}.#{primary_key}", orders)
 
       relation = relation.dup
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index d17861f407..8bd4732c0c 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -96,11 +96,11 @@ module ActiveRecord
       relation
     end
 
-    def having(*args)
-      return self if args.blank?
+    def having(opts, *rest)
+      return self if opts.blank?
 
       relation = clone
-      relation.having_values += build_where(*args)
+      relation.having_values += build_where(opts, rest)
       relation
     end