From 709a0a131021135e9fb7a2095fcfcbc223dfb126 Mon Sep 17 00:00:00 2001
From: Igor Babaev <igor@askmonty.org>
Date: Wed, 26 May 2010 13:18:18 -0700
Subject: MWL#106: Backport optimizations for derived tables and views. The
 main consolidated patch.

---
 sql/sql_list.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

(limited to 'sql/sql_list.h')

diff --git a/sql/sql_list.h b/sql/sql_list.h
index 93cdd20c299..f1b71b00cf6 100644
--- a/sql/sql_list.h
+++ b/sql/sql_list.h
@@ -168,6 +168,11 @@ public:
   {
     if (!list->is_empty())
     {
+      if (is_empty())
+      {
+        *this= *list;
+        return;
+      }
       *last= list->first;
       last= list->last;
       elements+= list->elements;
@@ -188,11 +193,13 @@ public:
     list_node *node= first;
     list_node *list_first= list->first;
     elements=0;
-    while (node && node != list_first)
+    while (node != list_first)
     {
       prev= &node->next;
       node= node->next;
       elements++;
+      if (node == &end_of_list)
+        return;
     }
     *prev= *last;
     last= prev;
-- 
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