diff --git a/lib/active_record/connection_adapters/oracle_enhanced/database_statements.rb b/lib/active_record/connection_adapters/oracle_enhanced/database_statements.rb
index 33feb53a0..ea14937d4 100644
--- a/lib/active_record/connection_adapters/oracle_enhanced/database_statements.rb
+++ b/lib/active_record/connection_adapters/oracle_enhanced/database_statements.rb
@@ -250,7 +250,14 @@ def empty_insert_statement_value
 
         # Writes LOB values from attributes for specified columns
         def write_lobs(table_name, klass, attributes, columns) #:nodoc:
-          id = quote(attributes[klass.primary_key])
+          if klass.primary_key.kind_of?(Array)
+            id_conditions = klass.primary_key.map { |key|
+              "#{quote_table_name(table_name)}.#{quote_column_name(key)} = #{quote(attributes[key])}"
+            }.join(' AND ')
+          else
+            id_conditions = "#{quote_table_name(table_name)}.#{quote_column_name(klass.primary_key)} = #{quote(attributes[klass.primary_key])}"
+          end
+
           columns.each do |col|
             value = attributes[col.name]
             # changed sequence of next two lines - should check if value is nil before converting to yaml
@@ -263,7 +270,7 @@ def write_lobs(table_name, klass, attributes, columns) #:nodoc:
             uncached do
               unless lob_record = select_one(sql = <<~SQL.squish, "Writable Large Object")
                 SELECT #{quote_column_name(col.name)} FROM #{quote_table_name(table_name)}
-                WHERE #{quote_column_name(klass.primary_key)} = #{id} FOR UPDATE
+                WHERE #{id_conditions} FOR UPDATE
               SQL
                 raise ActiveRecord::RecordNotFound, "statement #{sql} returned no rows"
               end