[SHOW] EXPLAIN UPDATE/DELETE, code re-structuring

- Handle another specific case where there the JOIN 
  never had a query plan, but had multiple join->cleanup(full=true) calls
- The idea that there can only be MAX_TABLES subuqeries/unions was 
  wrong. Switch QPF_query to using a Dynamic_array.
  = make Dynamic_array template support size growth. its underlying
    DYNAMIC_ARRAY supports it. (this part will need more polishing)

sql/opt_qpf.cc

@@ -13,8 +13,8 @@
 QPF_query::QPF_query()
 {
   upd_del_plan= NULL;
-  memset(&unions, 0, sizeof(unions));
-  memset(&selects, 0, sizeof(selects));
+  //memset(&unions, 0, sizeof(unions));
+  //memset(&selects, 0, sizeof(selects));
 }
 
 
@@ -22,25 +22,30 @@ QPF_query::~QPF_query()
 {
   delete upd_del_plan;
   uint i;
-  for (i=0 ; i < MAX_TABLES; i++)
-    delete unions[i];
-  for (i=0 ; i < MAX_TABLES; i++)
-    delete selects[i];
+  for (i= 0 ; i < unions.elements(); i++)
+    delete unions.at(i);
+  for (i= 0 ; i < selects.elements(); i++)
+    delete selects.at(i);
 }
 
 
 QPF_node *QPF_query::get_node(uint select_id)
 {
-  if (unions[select_id])
-    return unions[select_id];
+  QPF_union *u;
+  if ((u= get_union(select_id)))
+    return u;
   else
-    return selects[select_id];
+    return get_select(select_id);
 }
 
+QPF_union *QPF_query::get_union(uint select_id)
+{
+  return (unions.elements() > select_id) ? unions.at(select_id) : NULL;
+}
 
 QPF_select *QPF_query::get_select(uint select_id)
 {
-  return selects[select_id];
+  return (selects.elements() > select_id) ? selects.at(select_id) : NULL;
 }
 
 
@@ -49,8 +54,13 @@ void QPF_query::add_node(QPF_node *node)
   if (node->get_type() == QPF_node::QPF_UNION)
   {
     QPF_union *u= (QPF_union*)node;
-    DBUG_ASSERT(!unions[u->get_select_id()]);
-    unions[u->get_select_id()]= u;
+    uint select_id= u->get_select_id();
+    DBUG_ASSERT(!get_union(select_id));
+
+    if (unions.elements() <= select_id)
+      unions.resize(max(select_id+1, unions.elements()*2), NULL);
+
+    unions.at(select_id)= u;
   }
   else
   {
@@ -62,8 +72,12 @@ void QPF_query::add_node(QPF_node *node)
     }
     else
     {
-      DBUG_ASSERT(!selects[sel->select_id]);
-      selects[sel->select_id] = sel;
+      uint select_id= sel->select_id;
+      DBUG_ASSERT(!get_select(select_id));
+
+      if (selects.elements() <= select_id)
+        selects.resize(max(select_id+1, selects.elements()*2), NULL);
+      selects.at(select_id)= sel;
     }
   }
 }

sql/opt_qpf.h

@@ -209,6 +209,8 @@ class QPF_query : public Sql_alloc
   /* This will return a select (even if there is a union with this id) */
   QPF_select *get_select(uint select_id);
   
+  QPF_union *get_union(uint select_id);
+  
   /* QPF_delete inherits from QPF_update */
   QPF_update *upd_del_plan;
 
@@ -217,8 +219,10 @@ class QPF_query : public Sql_alloc
 
   MEM_ROOT *mem_root;
 private:
-  QPF_union *unions[MAX_TABLES];
-  QPF_select *selects[MAX_TABLES];
+  Dynamic_array<QPF_union*> unions;
+  Dynamic_array<QPF_select*> selects;
+  //QPF_union *unions[MAX_TABLES];
+  //QPF_select *selects[MAX_TABLES];
 };
 
 

sql/sql_array.h

@@ -106,6 +106,7 @@ template <class Elem> class Dynamic_array
 
   Elem& at(size_t idx)
   {
+    DBUG_ASSERT(idx < array.elements);
     return *(((Elem*)array.buffer) + idx);
   }
 
@@ -139,6 +140,23 @@ template <class Elem> class Dynamic_array
     array.elements= n;
   }
 
+  bool resize(size_t new_size, Elem default_val)
+  {
+    size_t old_size= elements();
+    if (allocate_dynamic(&array, new_size))
+      return true;
+    
+    if (new_size > old_size)
+    {
+      set_dynamic(&array, (uchar*)&default_val, new_size - 1);
+      /*for (size_t i= old_size; i != new_size; i++)
+      {
+        at(i)= default_val;
+      }*/
+    }
+    return false;
+  }
+
   ~Dynamic_array()
   {
     delete_dynamic(&array);

sql/sql_select.cc

@@ -11112,6 +11112,9 @@ void JOIN::cleanup(bool full)
     if (select_lex->select_number != UINT_MAX && 
         select_lex->select_number != INT_MAX /* this is not a UNION's "fake select */ && 
         have_query_plan != QEP_NOT_PRESENT_YET && 
+        have_query_plan != QEP_DELETED &&  // this happens when there was no QEP ever, but then
+                                           //cleanup() is called multiple times
+
         thd->lex->query_plan_footprint && // for "SET" command in SPs.
         !thd->lex->query_plan_footprint->get_select(select_lex->select_number))
     {