Added changelog for user search improvements

app/finders/autocomplete_users_finder.rb

@@ -58,7 +58,7 @@ class AutocompleteUsersFinder
   def users_from_project
     if author_id.present?
       union = Gitlab::SQL::Union
-        .new([project.team.users, User.where(id: author_id)])
+        .new([project.authorized_users, User.where(id: author_id)])
 
       User.from("(#{union.to_sql}) #{User.table_name}")
     else

changelogs/unreleased/users-autocomplete.yml

+---
+title: Improve performance of searching for and autocompleting of users
+merge_request:
+author:
+type: performance

lib/gitlab/sql/pattern.rb

@@ -38,16 +38,14 @@ module Gitlab
           if words.any?
             words.map { |word| arel_table[column].matches(to_pattern(word)) }.reduce(:and)
           else
-            sanitized_query = sanitize_sql_like(query)
-
             # No words of at least 3 chars, but we can search for an exact
             # case insensitive match with the query as a whole
             if lower_exact_match
               Arel::Nodes::NamedFunction
                 .new('LOWER', [arel_table[column]])
-                .eq(sanitized_query)
+                .eq(query)
             else
-              arel_table[column].matches(sanitized_query)
+              arel_table[column].matches(sanitize_sql_like(query))
             end
           end
         end