[SHOW] EXPLAIN UPDATE/DELETE, code reordering

- Add further details, the goal is to pass the testsuite
- SJM-nests are not printed correctly yet.

sql/opt_qpf.cc

@@ -17,6 +17,16 @@ QPF_query::QPF_query()
 }
 
 
+QPF_query::~QPF_query()
+{
+  uint i;
+  for (i=0 ; i < MAX_TABLES; i++)
+    delete unions[i];
+  for (i=0 ; i < MAX_TABLES; i++)
+    delete selects[i];
+}
+
+
 QPF_node *QPF_query::get_node(uint select_id)
 {
   if (unions[select_id])
@@ -178,6 +188,17 @@ int QPF_union::print_explain(QPF_query *query, select_result_sink *output,
 }
 
 
+QPF_select::~QPF_select()
+{
+  if (join_tabs)
+  {
+    for (uint i= 0; i< n_join_tabs; i++)
+      delete join_tabs[i];
+    my_free(join_tabs);
+  }
+} 
+
+
 int QPF_select::print_explain(QPF_query *query, select_result_sink *output,
                               uint8 explain_flags)
 {
@@ -222,6 +243,13 @@ int QPF_select::print_explain(QPF_query *query, select_result_sink *output,
       }
     }
   }
+
+  //psergey-TODO: print children here...
+  for (int i= 0; i < (int) children.elements(); i++)
+  {
+    QPF_node *node= query->get_node(children.at(i));
+    node->print_explain(query, output, explain_flags);
+  }
   return 0;
 }
 
@@ -259,7 +287,10 @@ int QPF_table_access::print_explain(select_result_sink *output, uint8 explain_fl
 
   /* `possible_keys` column */
   //push_str(item_list, "TODO");
-  item_list.push_back(item_null); 
+  if (possible_keys_str.length() > 0)
+    push_string(&item_list, &possible_keys_str);
+  else
+    item_list.push_back(item_null); 
 
   /* `key` */
   if (key_set)

sql/opt_qpf.h

@@ -48,33 +48,19 @@ class QPF_select : public QPF_node
 public:
   enum qpf_node_type get_type() { return QPF_SELECT; }
 
-#if 0  
-  /* Constructs a finished degenerate join plan */
-  QPF_select(int select_id_arg, const char *select_type_arg, const char* msg) : 
-    select_id(select_id_arg),
-    select_type(select_type_arg),
-    message(msg), 
-    join_tabs(NULL), n_join_tabs(0) 
-  {}
-  
-  /* Constructs an un-finished, non degenerate join plan. */
-  QPF_select(int select_id_arg, const char *select_type_arg) : 
-    select_id(select_id_arg),
-    select_type(select_type_arg),
-    message(NULL), 
-    join_tabs(NULL), n_join_tabs(0) 
-  {}
-#endif
   QPF_select() : 
     message(NULL), join_tabs(NULL),
     using_temporary(false), using_filesort(false)
   {}
+  
+  ~QPF_select();
 
   bool add_table(QPF_table_access *tab)
   {
     if (!join_tabs)
     {
-      join_tabs= (QPF_table_access**) malloc(sizeof(QPF_table_access*) * MAX_TABLES);
+      join_tabs= (QPF_table_access**) my_malloc(sizeof(QPF_table_access*) *
+                                                MAX_TABLES, MYF(0));
       n_join_tabs= 0;
     }
     join_tabs[n_join_tabs++]= tab;
@@ -103,6 +89,13 @@ class QPF_select : public QPF_node
   /* Global join attributes. In tabular form, they are printed on the first row */
   bool using_temporary;
   bool using_filesort;
+  
+  /* Child selects. TODO: join this with QPF_union's children? */
+  Dynamic_array<int> children;
+  void add_child(int select_no)
+  {
+    children.append(select_no);
+  }
 
   void print_tabular(select_result_sink *output, uint8 explain_flags//, 
                      //bool *printed_anything
@@ -143,10 +136,11 @@ class QPF_union : public QPF_node
   This is the whole query. 
 */
 
-class QPF_query 
+class QPF_query : public Sql_alloc
 {
 public:
   QPF_query();
+  ~QPF_query();
   void add_node(QPF_node *node);
   int print_explain(select_result_sink *output, uint8 explain_flags);
 
@@ -203,7 +197,7 @@ enum Extra_tag
 };
 
 
-class QPF_table_access
+class QPF_table_access : public Sql_alloc
 {
 public:
   void push_extra(enum Extra_tag extra_tag);
@@ -220,6 +214,7 @@ class QPF_table_access
   bool used_partitions_set;
 
   key_map possible_keys;
+  StringBuffer<256> possible_keys_str;
   
   uint key_no;
   uint key_length;

sql/sql_parse.cc

@@ -4814,7 +4814,12 @@ static bool execute_sqlcom_select(THD *thd, TABLE_LIST *all_tables)
       thd->lex->query_plan_footprint= new QPF_query;
       res= mysql_explain_union(thd, &thd->lex->unit, result);
 
-      thd->lex->query_plan_footprint->print_explain(result, thd->lex->describe);
+      if (!res)
+      {
+        thd->lex->query_plan_footprint->print_explain(result, thd->lex->describe);
+      }
+      delete thd->lex->query_plan_footprint;
+      thd->lex->query_plan_footprint= NULL;
 
       //psergey-todo: here, produce the EXPLAIN output.
       //  mysql_explain_union() itself is only responsible for calling

sql/sql_select.cc

@@ -22903,6 +22903,21 @@ void QPF_table_access::push_extra(enum Extra_tag extra_tag)
   extra_tags.append(extra_tag);
 }
 
+void append_possible_keys(String *str, TABLE *table, key_map possible_keys)
+{
+  uint j;
+  for (j=0 ; j < table->s->keys ; j++)
+  {
+    if (possible_keys.is_set(j))
+    {
+      if (str->length())
+        str->append(',');
+      str->append(table->key_info[j].name, 
+                  strlen(table->key_info[j].name),
+                  system_charset_info);
+    }
+  }
+}
 
 /*
   Save Query Plan Footprint
@@ -22982,9 +22997,6 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
     for (JOIN_TAB *tab= first_breadth_first_tab(join, WALK_OPTIMIZATION_TABS); tab;
          tab= next_breadth_first_tab(join, WALK_OPTIMIZATION_TABS, tab))
     {
-      QPF_table_access *qpt= new QPF_table_access;
-      qp_sel->add_table(qpt);
-
       if (tab->bush_root_tab)
       {
         JOIN_TAB *first_sibling= tab->bush_root_tab->bush_children->start;
@@ -23020,7 +23032,6 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
         continue;
       }
 
-
       if (join->table_access_tabs == join->join_tab &&
           tab == (first_top_tab + join->const_tables) && pre_sort_join_tab)
       {
@@ -23028,8 +23039,12 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
         tab= pre_sort_join_tab;
       }
 
+      QPF_table_access *qpt= new QPF_table_access;
+      qp_sel->add_table(qpt);
+
       /* id */
-      qp_sel->select_id= select_id;
+      // TODO: this can be '2' in case of SJM nests..
+      //qp_sel->select_id= select_id;
 
       /* select_type */
       //const char* stype= printing_materialize_nest? "MATERIALIZED" : 
@@ -23099,6 +23114,7 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
 
       /* Build "possible_keys" value */
       qpt->possible_keys= tab->keys;
+      append_possible_keys(&qpt->possible_keys_str, table, tab->keys);
 
       /* Build "key", "key_len", and "ref" */
 
@@ -23379,9 +23395,10 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
         */
         if (quick_type == QUICK_SELECT_I::QS_TYPE_RANGE)
         {
-          qpt->push_extra(ET_USING_MRR);
           explain_append_mrr_info((QUICK_RANGE_SELECT*)(tab->select->quick),
                                   &qpt->mrr_type);
+          if (qpt->mrr_type.length() > 0)
+            qpt->push_extra(ET_USING_MRR);
         }
 
 	if (need_tmp_table)
@@ -23463,6 +23480,23 @@ int JOIN::save_qpf(QPF_query *output, bool need_tmp_table, bool need_order,
     }
     output->add_node(qp_sel);
   }
+
+
+  ///
+  for (SELECT_LEX_UNIT *unit= join->select_lex->first_inner_unit();
+       unit;
+       unit= unit->next_unit())
+  {
+    /* 
+      Display subqueries only if they are not parts of eliminated WHERE/ON
+      clauses.
+    */
+    if (!(unit->item && unit->item->eliminated))
+    {
+      qp_sel->add_child(unit->first_select()->select_number);
+    }
+  }
+
   DBUG_RETURN(error);
 }