WL#5252: Deprecate --optimizer_search_depth=63

Add deprecation warning when variable optimizer_search_depth is given
the value 63.
      
  mysql-test/r/greedy_optimizer.result
    Updated with warning text.
  mysql-test/r/mysqld--help-notwin.result
    Updated with warning from mysqld --help --verbose.
  mysql-test/r/mysqld--help-win.result
    Updated with warning from mysqld --help --verbose.
  sql/sys_vars.cc
    Added an update check function to the constructor invocation for
    the optimizer_search_depth variable. The function emits a
    warning message for the value 63.

mysql-test/r/greedy_optimizer.result

@@ -115,6 +115,8 @@ select @@optimizer_prune_level;
 @@optimizer_prune_level
 1
 set optimizer_search_depth=63;
+Warnings:
+Warning	1287	'optimizer-search-depth=63' is deprecated and will be removed in a future release. Please use a search depth less than 63 instead
 select @@optimizer_search_depth;
 @@optimizer_search_depth
 63

mysql-test/r/mysqld--help-notwin.result

@@ -396,8 +396,9 @@ The following options may be given as the first argument:
  relation result in faster optimization, but may produce
  very bad query plans. If set to 0, the system will
  automatically pick a reasonable value; if set to 63, the
- optimizer will switch to the original find_best
+ optimizer will switch to the original find_best search.
- search(used for testing/comparison)
+ NOTE: The value 63 and its associated behaviour is
+ deprecated
  --optimizer-switch=name 
  optimizer_switch=option=val[,option=val...], where option
  is one of {index_merge, index_merge_union,

mysql-test/r/mysqld--help-win.result

@@ -396,8 +396,9 @@ The following options may be given as the first argument:
  relation result in faster optimization, but may produce
  very bad query plans. If set to 0, the system will
  automatically pick a reasonable value; if set to 63, the
- optimizer will switch to the original find_best
+ optimizer will switch to the original find_best search.
- search(used for testing/comparison)
+ NOTE: The value 63 and its associated behaviour is
+ deprecated
  --optimizer-switch=name 
  optimizer_switch=option=val[,option=val...], where option
  is one of {index_merge, index_merge_union,

sql/sys_vars.cc

@@ -1305,6 +1305,17 @@ static Sys_var_ulong Sys_optimizer_prune_level(
        SESSION_VAR(optimizer_prune_level), CMD_LINE(REQUIRED_ARG),
        VALID_RANGE(0, 1), DEFAULT(1), BLOCK_SIZE(1));
 
+/** Warns about deprecated value 63 */
+static bool fix_optimizer_search_depth(sys_var *self, THD *thd,
+                                       enum_var_type type)
+{
+  SV *sv= type == OPT_GLOBAL ? &global_system_variables : &thd->variables;
+  if (sv->optimizer_search_depth == MAX_TABLES+2)
+    WARN_DEPRECATED(thd, 6, 0, "optimizer-search-depth=63",
+                    "a search depth less than 63");
+  return false;
+}
+
 static Sys_var_ulong Sys_optimizer_search_depth(
        "optimizer_search_depth",
        "Maximum depth of search performed by the query optimizer. Values "
@@ -1313,10 +1324,12 @@ static Sys_var_ulong Sys_optimizer_search_depth(
        "than the number of tables in a relation result in faster "
        "optimization, but may produce very bad query plans. If set to 0, "
        "the system will automatically pick a reasonable value; if set to "
-       "63, the optimizer will switch to the original find_best search"
+       "63, the optimizer will switch to the original find_best search. "
-       "(used for testing/comparison)",
+       "NOTE: The value 63 and its associated behaviour is deprecated",
        SESSION_VAR(optimizer_search_depth), CMD_LINE(REQUIRED_ARG),
-       VALID_RANGE(0, MAX_TABLES+2), DEFAULT(MAX_TABLES+1), BLOCK_SIZE(1));
+       VALID_RANGE(0, MAX_TABLES+2), DEFAULT(MAX_TABLES+1), BLOCK_SIZE(1),
+       NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(0),
+       ON_UPDATE(fix_optimizer_search_depth));
 
 static const char *optimizer_switch_names[]=
 {