Fix sorting of NULL values (Should always be first)

Fix problem with HAVING and MAX() IS NOT NULL


Docs/manual.texi:
  Changelog & NULL usage with ORDER BY
client/mysqldump.c:
  Cleanup disable keys
mysql-test/r/distinct.result:
  Fix results after ORDER BY with NULL fix
mysql-test/r/group_by.result:
  Fix results after ORDER BY with NULL fix
mysql-test/r/having.result:
  Testcase for bug with HAVING
mysql-test/t/distinct.test:
  Test for DISTINCT + ORDER BY DESC bug
mysql-test/t/having.test:
  Test of HAVING and MAX IS NOT NULL
sql/filesort.cc:
  Fix sorting of NULL values (Should always be first)
sql/item.h:
  Fix problem with HAVING and MAX() IS NOT NULL
sql/item_sum.h:
  Fix problem with HAVING and MAX() IS NOT NULL
sql/opt_range.cc:
  Fix problem with HAVING and MAX() IS NOT NULL
sql/opt_range.h:
  Fix sorting of NULL values
sql/sql_select.cc:
  Fix sorting of ORDER BY ... DESC on NULL values.

1 files changed, 3 insertions, 0 deletions

diff --git a/sql/opt_range.h b/sql/opt_range.h
index 83eb10235ea..f48a3936a17 100644
--- a/sql/opt_range.h
+++ b/sql/opt_range.h
@@ -77,6 +77,7 @@ public:
   void reset(void) { next=0; it.rewind(); }
   int init() { return error=file->index_init(index); }
   virtual int get_next();
+  virtual bool reverse_sorted() { return 0; }
   int cmp_next(QUICK_RANGE *range);
   bool unique_key_range();
 };
@@ -87,6 +88,7 @@ class QUICK_SELECT_DESC: public QUICK_SELECT
 public:
   QUICK_SELECT_DESC(QUICK_SELECT *q, uint used_key_parts);
   int get_next();
+  bool reverse_sorted() { return 1; }
 private:
   int cmp_prev(QUICK_RANGE *range);
   bool range_reads_after_key(QUICK_RANGE *range);
@@ -96,6 +98,7 @@ private:
   List_iterator<QUICK_RANGE> rev_it;
 };
 
+
 class SQL_SELECT :public Sql_alloc {
  public:
   QUICK_SELECT *quick;		// If quick-select used