- Backport @@optimizer_switch support from 6.0

- Add support for setting it as a server commandline argument
- Add support for those switches:
  = no_index_merge
  = no_index_merge_union
  = no_index_merge_sort_union
  = no_index_merge_intersection

mysql-test/r/index_merge_myisam.result:
  Testcases for index_merge related @@optimizer_switch flags.
mysql-test/t/index_merge_myisam.test:
  Testcases for index_merge related @@optimizer_switch flags.
sql/set_var.cc:
  - Backport @@optimizer_switch support from 6.0
  - Add support for setting it as a server commandline argument
sql/sql_class.h:
  - Backport @@optimizer_switch support from 6.0
sql/sql_select.h:
  - Backport @@optimizer_switch support from 6.0

1 files changed, 18 insertions, 1 deletions

diff --git a/sql/set_var.h b/sql/set_var.h
index b6c67d1ab4a..f07facde0b0 100644
--- a/sql/set_var.h
+++ b/sql/set_var.h
@@ -31,7 +31,7 @@ typedef struct system_variables SV;
 typedef struct my_locale_st MY_LOCALE;
 
 extern TYPELIB bool_typelib, delay_key_write_typelib, sql_mode_typelib,
-  slave_exec_mode_typelib;
+  optimizer_switch_typelib, slave_exec_mode_typelib;
 
 typedef int (*sys_check_func)(THD *,  set_var *);
 typedef bool (*sys_update_func)(THD *, set_var *);
@@ -532,6 +532,23 @@ public:
 };
 
 
+class sys_var_thd_optimizer_switch :public sys_var_thd_enum
+{
+public:
+  sys_var_thd_optimizer_switch(sys_var_chain *chain, const char *name_arg, 
+                               ulong SV::*offset_arg)
+    :sys_var_thd_enum(chain, name_arg, offset_arg, &optimizer_switch_typelib)
+  {}
+  bool check(THD *thd, set_var *var)
+  {
+    return check_set(thd, var, enum_names);
+  }
+  void set_default(THD *thd, enum_var_type type);
+  uchar *value_ptr(THD *thd, enum_var_type type, LEX_STRING *base);
+  static bool symbolic_mode_representation(THD *thd, ulonglong sql_mode,
+                                           LEX_STRING *rep);
+};
+
 extern void fix_sql_mode_var(THD *thd, enum_var_type type);
 
 class sys_var_thd_sql_mode :public sys_var_thd_enum