From 283d9d50386e14534885c826b4037889b42f8b30 Mon Sep 17 00:00:00 2001
From: jdenquin <jdenquin@gmail.com>
Date: Wed, 9 Oct 2024 01:21:57 +0200
Subject: [PATCH] add notes

---
 lib/core_extensions/active_record/relation.rb | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/core_extensions/active_record/relation.rb b/lib/core_extensions/active_record/relation.rb
index 9327f547..9b047805 100644
--- a/lib/core_extensions/active_record/relation.rb
+++ b/lib/core_extensions/active_record/relation.rb
@@ -81,10 +81,19 @@ def window!(name, **opts)
         self
       end
 
+      # The LIMIT BY clause permit to improve deduplication based on a unique key, it has better performances than
+      # the GROUP BY clause
+      #
+      #   users = User.limit_by(1, id)
+      #   # SELECT users.* FROM users LIMIT 1 BY id
+      #
+      # An <tt>ActiveRecord::ActiveRecordError</tt> will be reaised if database is not Clickhouse.
+      # @param [Array] opts
       def limit_by(*opts)
         spawn.limit_by!(*opts)
       end
 
+      # @param [Array] opts
       def limit_by!(*opts)
         @values[:limit_by] = *opts
         self