Preparatory (and the most problematic) patch for Bug#7306

"the server side preparedStatement error for LIMIT placeholder",
which moves all uses of LIMIT clause from PREPARE to OPTIMIZE
and later steps.
After-review fixes.


mysql-test/r/group_min_max.result:
  Test results fixed for EXPLAINs when using GROUP_MIN_MAX access plan.
sql/item_subselect.cc:
  Move setting of the internal LIMIT used for IN/ALL/ANY/EXISTS 
  subqueries to one place: Item_exists_subselect::fix_length_and_dec().
  This implies that unit->select_limit_cnt is not set until the item is 
  fixed. This is OK, as now LIMIT values are not used until JOIN::optimize.
sql/mysql_priv.h:
  setup_tables no longer needs a special flag for the case when
  it's called from JOIN::reinit() (we don't need to call setup_tables
  between two executions of a correlated subquery).
sql/opt_range.cc:
  Fix a glitch in GROUP_MIN_MAX access plan: we should use table metadata,
  not field data, to evaluate max_used_key_length, which is then
  used for explain.
sql/sp.cc:
  - setup_tables signature changed.
sql/sql_base.cc:
  - setup_tables no longer needs a special mode for subqueries.
    Unused checks were removed.
sql/sql_delete.cc:
  - setup_tables signature changed
sql/sql_help.cc:
  - setup_tables signature changed
sql/sql_insert.cc:
  - setup_tables signature changed
sql/sql_lex.cc:
  Consolidate setting of internal LIMIT for IN/ALL/ANY/EXISTS subqeries
  in one place, and hence remove it from st_select_lex::test_limit().
sql/sql_lex.h:
  Cleanup signature of st_select_lex_unit::init_prepare_fake_select_lex().
sql/sql_load.cc:
  - setup_tables signature changed
sql/sql_olap.cc:
  - setup_tables signature changed
sql/sql_parse.cc:
  - st_select_lex_unit::set_limit() signature changed
sql/sql_select.cc:
  Move setting of JOIN::select_limit from JOIN::prepare
  to JOIN::optimize. At prepare, limit is unknown yet.
  Remove excessive cleanups from JOIN::reinit which were overwriting
  join->join_tab[i]->table->used_keys. This fixes the bug which was triggered
  by the change in item_subselect.cc.
sql/sql_union.cc:
  Class st_select_lex_unit was changed to avoid calls to 
   st_select_lex_unit::set_limit from places where it may be unknown.
  Now unit->select_limit_cnt is set at ::exec(). 
  st_select_lex_unit::init_prepare_fake_select_lex(): 
   - move out set_limit functionality
   - remove a few lines of dead code.
  st_select_lex_unit::prepare():
    - now we don't call set_limit at the time of prepare, so the value  
      of unit->select_limit_cnt may be unknown here. Use sl->select_limit
      instead.
  st_select_lex_unit::exec():
    - cleanup
    - call set_limit explicitly as it has been moved out of 
     init_prepare_fake_select_lex.
sql/sql_update.cc:
  - setup_tables signature changed

1 files changed, 8 insertions, 28 deletions

diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index 00770ba02a2..21549f76350 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -115,27 +115,15 @@ bool select_union::flush()
     options of SELECT
 */
 
-ulong
+void
 st_select_lex_unit::init_prepare_fake_select_lex(THD *thd) 
 {
-  ulong options_tmp= thd->options | fake_select_lex->options;
   thd->lex->current_select= fake_select_lex;
-  offset_limit_cnt= global_parameters->offset_limit;
-  select_limit_cnt= global_parameters->select_limit +
-    global_parameters->offset_limit;
-
-  if (select_limit_cnt < global_parameters->select_limit)
-    select_limit_cnt= HA_POS_ERROR;		// no limit
-  if (select_limit_cnt == HA_POS_ERROR)
-    options_tmp&= ~OPTION_FOUND_ROWS;
-  else if (found_rows_for_union && !thd->lex->describe)
-    options_tmp|= OPTION_FOUND_ROWS;
   fake_select_lex->ftfunc_list_alloc.empty();
   fake_select_lex->ftfunc_list= &fake_select_lex->ftfunc_list_alloc;
   fake_select_lex->table_list.link_in_list((byte *)&result_table_list,
 					   (byte **)
 					   &result_table_list.next_local);
-  return options_tmp;
 }
 
 
@@ -217,10 +205,9 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
       goto err;
 
     thd_arg->lex->current_select= sl;
-    set_limit(sl, sl);
 
     can_skip_order_by= is_union &&
-                       (!sl->braces || select_limit_cnt == HA_POS_ERROR);
+                       (!sl->braces || sl->select_limit == HA_POS_ERROR);
     
     res= join->prepare(&sl->ref_pointer_array,
 		       (TABLE_LIST*) sl->table_list.first, sl->with_wild,
@@ -340,7 +327,7 @@ bool st_select_lex_unit::prepare(THD *thd_arg, select_result *sel_result,
       if (arena->is_stmt_prepare())
       {
 	/* prepare fake select to initialize it correctly */
-	(void) init_prepare_fake_select_lex(thd);
+	init_prepare_fake_select_lex(thd);
         /*
           Should be done only once (the only item_list per statement).
         */
@@ -429,12 +416,8 @@ bool st_select_lex_unit::exec()
 	res= sl->join->reinit();
       else
       {
-	if (sl != global_parameters && !describe)
-	{
-	  offset_limit_cnt= sl->offset_limit;
-	  select_limit_cnt= sl->select_limit+sl->offset_limit;
-	}
-	else
+        set_limit(sl);
+	if (sl == global_parameters || describe)
 	{
 	  offset_limit_cnt= 0;
 	  /*
@@ -443,11 +426,7 @@ bool st_select_lex_unit::exec()
 	  */
 	  if (sl->order_list.first || describe)
 	    select_limit_cnt= HA_POS_ERROR;
-	  else
-	    select_limit_cnt= sl->select_limit+sl->offset_limit;
-	}
-	if (select_limit_cnt < sl->select_limit)
-	  select_limit_cnt= HA_POS_ERROR;		// no limit
+        }
 
         /*
           When using braces, SQL_CALC_FOUND_ROWS affects the whole query:
@@ -512,7 +491,8 @@ bool st_select_lex_unit::exec()
 
     if (!thd->is_fatal_error)				// Check if EOM
     {
-      ulong options_tmp= init_prepare_fake_select_lex(thd);
+      set_limit(global_parameters);
+      init_prepare_fake_select_lex(thd);
       JOIN *join= fake_select_lex->join;
       if (!join)
       {