bk commit into 5.0 tree (ramil:1.2097) BUG#18306

[ramil]

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5.0 repository of ram. When ram does a push these changes will
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ChangeSet
  1.2097 06/03/21 16:22:34 ramil@stripped +1 -0
  Fix for bug #18306: MySQL crashes and restarts using subquery.
  

  sql/opt_range.cc
    1.206 06/03/21 16:22:25 ramil@stripped +11 -3
    Fix for bug #18306: MySQL crashes and restarts using subquery.
    - we have to restore the thread's mem_root here as we can come across 
      subselect items.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	ramil
# Host:	myoffice.izhnet.ru
# Root:	/usr/home/ram/work/mysql-5.0

--- 1.205/sql/opt_range.cc	2006-02-25 19:46:26 +04:00
+++ 1.206/sql/opt_range.cc	2006-03-21 16:22:25 +04:00
@@ -3604,9 +3604,17 @@ static SEL_TREE *get_mm_tree(PARAM *para
   /* Here when simple cond */
   if (cond->const_item())
   {
-    if (cond->val_int())
-      DBUG_RETURN(new SEL_TREE(SEL_TREE::ALWAYS));
-    DBUG_RETURN(new SEL_TREE(SEL_TREE::IMPOSSIBLE));
+    /*
+      As we can come across a subselect item here (which assumes 
+      all the memory allocated has the same life span as the subselect 
+      item itself) we have to restore the thread's mem_root.
+    */
+    MEM_ROOT *tmp_root= param->mem_root;
+    param->thd->mem_root= param->old_root;
+    tree= cond->val_int() ? new(tmp_root) SEL_TREE(SEL_TREE::ALWAYS) :
+                            new(tmp_root) SEL_TREE(SEL_TREE::IMPOSSIBLE);
+    param->thd->mem_root= tmp_root;
+    DBUG_RETURN(tree);
   }
 
   table_map ref_tables= 0;