From f852b608d140addcbdc7ecb85d42eef0bbd512c5 Mon Sep 17 00:00:00 2001
From: Yasuo Honda <yasuo.honda@gmail.com>
Date: Mon, 2 May 2016 13:31:06 +0000
Subject: Raise ArgumentError if limit and lock are used for Oracle12 visitor
 it would generates `SELECT ... FETCH FIRST n ROWS ONLY FOR UPDATE` which
 causes Oracle 12c database returns this error :

ORA-02014: cannot select FOR UPDATE from view with DISTINCT, GROUP BY, etc.
---
 lib/arel/visitors/oracle12.rb | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

(limited to 'lib')

diff --git a/lib/arel/visitors/oracle12.rb b/lib/arel/visitors/oracle12.rb
index 4a42343c9b..d21a829848 100644
--- a/lib/arel/visitors/oracle12.rb
+++ b/lib/arel/visitors/oracle12.rb
@@ -6,10 +6,12 @@ module Arel
       def visit_Arel_Nodes_SelectStatement o, collector
         # Oracle does not allow LIMIT clause with select for update
         if o.limit && o.lock
-          o = o.dup
-          o.limit = []
+          raise ArgumentError, <<-MSG
+            'Combination of limit and lock is not supported.
+            because generated SQL statements
+            `SELECT FOR UPDATE and FETCH FIRST n ROWS` generates ORA-02014.`
+          MSG
         end
-
         super
       end
 
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