From 1180c22aef303d85926acba398500c6abbd5d0cb Mon Sep 17 00:00:00 2001
From: "davi@moksha.local" <>
Date: Thu, 30 Aug 2007 16:11:53 -0300
Subject: [PATCH] Bug#28587 SELECT is blocked by INSERT waiting on read lock,
 even with low_priority_updates

The problem is that a SELECT on one thread is blocked by INSERT ... ON
DUPLICATE KEY UPDATE on another thread even when low_priority_updates is
activated.

The solution is to possibly downgrade the lock type to the setting of
low_priority_updates if the INSERT cannot be concurrent.
---
 sql/sql_insert.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc
index bd21d929291..f07af393070 100644
--- a/sql/sql_insert.cc
+++ b/sql/sql_insert.cc
@@ -417,7 +417,7 @@ void upgrade_lock_type(THD *thd, thr_lock_type *lock_type,
   if (duplic == DUP_UPDATE ||
       duplic == DUP_REPLACE && *lock_type == TL_WRITE_CONCURRENT_INSERT)
   {
-    *lock_type= TL_WRITE;
+    *lock_type= TL_WRITE_DEFAULT;
     return;
   }