cleanup st_select_lex_unit::explainable

sql/sql_delete.cc

@@ -199,23 +199,12 @@ bool Update_plan::save_explain_data_intern(MEM_ROOT *mem_root,
                             &explain->mrr_type);
   }
 
-  bool skip= updating_a_view;
-
   /* Save subquery children */
   for (SELECT_LEX_UNIT *unit= select_lex->first_inner_unit();
        unit;
        unit= unit->next_unit())
   {
-    if (skip)
+    if (unit->explainable())
-    {
-      skip= false;
-      continue;
-    }
-    /* 
-      Display subqueries only if they are not parts of eliminated WHERE/ON
-      clauses.
-    */
-    if (!(unit->item && unit->item->eliminated))
       explain->add_child(unit->first_select()->select_number);
   }
   return 0;
@@ -395,7 +384,6 @@ bool mysql_delete(THD *thd, TABLE_LIST *table_list, COND *conds,
   table->map=1;
   query_plan.select_lex= thd->lex->first_select_lex();
   query_plan.table= table;
-  query_plan.updating_a_view= MY_TEST(table_list->view);
 
   if (mysql_prepare_delete(thd, table_list, select_lex->with_wild,
                            select_lex->item_list, &conds,

sql/sql_insert.cc

@@ -657,24 +657,12 @@ static void save_insert_query_plan(THD* thd, TABLE_LIST *table_list)
 
   thd->lex->explain->add_insert_plan(explain);
   
-  /* See Update_plan::updating_a_view for details */
-  bool skip= MY_TEST(table_list->view);
-
   /* Save subquery children */
   for (SELECT_LEX_UNIT *unit= thd->lex->first_select_lex()->first_inner_unit();
        unit;
        unit= unit->next_unit())
   {
-    if (skip)
+    if (unit->explainable())
-    {
-      skip= false;
-      continue;
-    }
-    /* 
-      Table elimination doesn't work for INSERTS, but let's still have this
-      here for consistency
-    */
-    if (!(unit->item && unit->item->eliminated))
       explain->add_child(unit->first_select()->select_number);
   }
 }

sql/sql_lex.cc

@@ -5225,10 +5225,8 @@ int st_select_lex_unit::save_union_explain_part2(Explain_query *output)
     for (SELECT_LEX_UNIT *unit= fake_select_lex->first_inner_unit(); 
          unit; unit= unit->next_unit())
     {
-      if (!(unit->item && unit->item->eliminated))
+      if (unit->explainable())
-      {
         eu->add_child(unit->first_select()->select_number);
-      }
     }
     fake_select_lex->join->explain= &eu->fake_select_lex_explain;
   }

sql/sql_lex.h

@@ -995,6 +995,19 @@ public:
   int save_union_explain_part2(Explain_query *output);
   unit_common_op common_op();
 
+  bool explainable()
+  {
+    /*
+      Save plans for child subqueries, when
+      (1) they are not parts of eliminated WHERE/ON clauses.
+      (2) they are not merged derived tables
+      (3) they are not hanging CTEs (they are needed for execution)
+    */
+    return !(item && item->eliminated) &&
+           !(derived && !derived->is_materialized_derived()) &&
+           !(with_element && (!derived || !derived->derived_result));
+  }
+
   void reset_distinct();
   void fix_distinct();
 
@@ -2942,15 +2955,6 @@ protected:
   bool impossible_where;
   bool no_partitions;
 public:
-  /*
-    When single-table UPDATE updates a VIEW, that VIEW's select is still
-    listed as the first child.  When we print EXPLAIN, it looks like a
-    subquery.
-    In order to get rid of it, updating_a_view=TRUE means that first child
-    select should not be shown when printing EXPLAIN.
-  */
-  bool updating_a_view;
-   
   /* Allocate things there */
   MEM_ROOT *mem_root;
 

sql/sql_select.cc

@@ -26745,21 +26745,8 @@ int JOIN::save_explain_data_intern(Explain_query *output,
        tmp_unit;
        tmp_unit= tmp_unit->next_unit())
   {
-    /* 
+    if (tmp_unit->explainable())
-      Display subqueries only if 
-      (1) they are not parts of ON clauses that were eliminated by table 
-          elimination.
-      (2) they are not merged derived tables
-      (3) they are not hanging CTEs (they are needed for execution)
-    */
-    if (!(tmp_unit->item && tmp_unit->item->eliminated) &&    // (1)
-        (!tmp_unit->derived ||
-         tmp_unit->derived->is_materialized_derived()) &&     // (2)
-        !(tmp_unit->with_element &&
-          (!tmp_unit->derived || !tmp_unit->derived->derived_result))) // (3)
-   {
       explain->add_child(tmp_unit->first_select()->select_number);
-    }
   }
 
   if (select_lex->is_top_level_node())
@@ -26813,16 +26800,7 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
       DBUG_ASSERT(ref == unit->item);
     }
 
-    /* 
+    if (unit->explainable())
-      Save plans for child subqueries, when
-      (1) they are not parts of eliminated WHERE/ON clauses.
-      (2) they are not VIEWs that were "merged for INSERT".
-      (3) they are not hanging CTEs (they are needed for execution)
-    */
-    if (!(unit->item && unit->item->eliminated) &&                     // (1)
-        !(unit->derived && unit->derived->merged_for_insert) &&        // (2)
-        !(unit->with_element &&
-          (!unit->derived || !unit->derived->derived_result)))         // (3)
     {
       if (mysql_explain_union(thd, unit, result))
         DBUG_VOID_RETURN;

sql/sql_update.cc

@@ -438,7 +438,6 @@ int mysql_update(THD *thd,
     my_error(ER_NON_UPDATABLE_TABLE, MYF(0), table_list->alias.str, "UPDATE");
     DBUG_RETURN(1);
   }
-  query_plan.updating_a_view= MY_TEST(table_list->view);
   
   /* Calculate "table->covering_keys" based on the WHERE */
   table->covering_keys= table->s->keys_in_use;