# MDEV-239: Assertion `field_types == 0 ... ' failed in Protocol_text::store...

- Make all functions that produce parts of EXPLAIN output take 
  explain_flags as parameter, instead of looking into thd->lex->describe

mysql-test/r/show_explain.result

@@ -309,4 +309,32 @@ a
 4
 set debug='';
 DROP TABLE t2;
+#
+# MDEV-239: Assertion `field_types == 0 ... ' failed in Protocol_text::store(double, uint32, String*) with 
+#          SHOW EXPLAIN over EXPLAIN EXTENDED
+#
+CREATE TABLE t2 (a INT);
+INSERT INTO t2 VALUES (1),(2),(1),(4),(2);
+EXPLAIN EXTENDED SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a ;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	100.00	Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` join `test`.`t2` group by `test`.`t2`.`a`
+set @show_explain_probe_select_id=1;
+set debug='d,show_explain_probe_join_exec_end';
+EXPLAIN EXTENDED SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a ;
+show explain for $thr2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	Using temporary; Using filesort
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	EXPLAIN EXTENDED SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	100.00	Using temporary; Using filesort
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	5	100.00	Using join buffer (flat, BNL join)
+Warnings:
+Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` join `test`.`t2` group by `test`.`t2`.`a`
+set debug='';
+DROP TABLE t2;
 drop table t0,t1;

mysql-test/t/show_explain.test

@@ -319,11 +319,34 @@ evalp show explain for $thr2;
 connection con1;
 reap;
 set debug='';
+DROP TABLE t2;
 
 
-## TODO: Test this: have several SHOW EXPLAIN requests be queued up for a
-##       thread and served together.
+--echo #
+--echo # MDEV-239: Assertion `field_types == 0 ... ' failed in Protocol_text::store(double, uint32, String*) with 
+--echo #          SHOW EXPLAIN over EXPLAIN EXTENDED
+--echo #
+
+
+CREATE TABLE t2 (a INT); 
+INSERT INTO t2 VALUES (1),(2),(1),(4),(2);
+
+EXPLAIN EXTENDED SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a ;
+
+set @show_explain_probe_select_id=1;
+set debug='d,show_explain_probe_join_exec_end';
+send EXPLAIN EXTENDED SELECT alias.a FROM t2, ( SELECT * FROM t2 ) AS alias GROUP BY alias.a ;
 
+connection default;
+--source include/wait_condition.inc
+evalp show explain for $thr2;
+connection con1;
+reap;
+set debug='';
 DROP TABLE t2;
 
+
+## TODO: Test this: have several SHOW EXPLAIN requests be queued up for a
+##       thread and served together.
+
 drop table t0,t1;

sql/sql_class.cc

@@ -3039,7 +3039,7 @@ void Show_explain_request::get_explain_data(void *arg)
                       target_thd->query_length(),
                       &my_charset_bin);
 
-  if (target_thd->lex->unit.print_explain(req->explain_buf))
+  if (target_thd->lex->unit.print_explain(req->explain_buf, 0 /* explain flags */))
     req->failed_to_produce= TRUE;
 
   target_thd->restore_active_arena((Query_arena*)req->request_thd, 

sql/sql_lex.cc

@@ -3746,12 +3746,13 @@ bool st_select_lex::is_merged_child_of(st_select_lex *ancestor)
 }
 
 
-int st_select_lex::print_explain(select_result_sink *output)
+int st_select_lex::print_explain(select_result_sink *output, 
+                                 uint8 explain_flags)
 {
   int res;
   if (join && join->optimized == 2)
   {
-    res= join->print_explain(output, TRUE,
+    res= join->print_explain(output, explain_flags, TRUE,
                              join->need_tmp, // need_tmp_table
                              (join->order != 0 && !join->skip_sort_order), // bool need_order
                              join->select_distinct, // bool distinct
@@ -3769,7 +3770,7 @@ int st_select_lex::print_explain(select_result_sink *output)
       */
       if (!(unit->item && unit->item->eliminated))
       {
-        unit->print_explain(output);
+        unit->print_explain(output, explain_flags);
       }
     }
   }
@@ -3777,7 +3778,7 @@ int st_select_lex::print_explain(select_result_sink *output)
   {
     /* Produce "not yet optimized" line */
     const char *msg="Not yet optimized";
-    res= join->print_explain(output, TRUE,
+    res= join->print_explain(output, explain_flags, TRUE,
                              FALSE, // need_tmp_table, 
                              FALSE, // bool need_order,
                              FALSE, // bool distinct,
@@ -3788,7 +3789,8 @@ err:
 }
 
 
-int st_select_lex_unit::print_explain(select_result_sink *output)
+int st_select_lex_unit::print_explain(select_result_sink *output, 
+                                      uint8 explain_flags)
 {
   int res= 0;
   SELECT_LEX *first= first_select();
@@ -3804,7 +3806,7 @@ int st_select_lex_unit::print_explain(select_result_sink *output)
 
   for (SELECT_LEX *sl= first; sl; sl= sl->next_select())
   {
-    if ((res= sl->print_explain(output)))
+    if ((res= sl->print_explain(output, explain_flags)))
       break;
   }
 
@@ -3814,7 +3816,7 @@ int st_select_lex_unit::print_explain(select_result_sink *output)
   if (fake_select_lex && !fake_select_lex->join)
   {
     res= print_fake_select_lex_join(output, TRUE /* on the fly */,
-                                    fake_select_lex, 0 /* flags */);
+                                    fake_select_lex, explain_flags);
   }
   return res;
 }

sql/sql_lex.h

@@ -595,7 +595,7 @@ public:
   friend int subselect_union_engine::exec();
 
   List<Item> *get_unit_column_types();
-  int print_explain(select_result_sink *output);
+  int print_explain(select_result_sink *output, uint8 explain_flags);
 };
 
 typedef class st_select_lex_unit SELECT_LEX_UNIT;
@@ -918,7 +918,7 @@ public:
   bool save_prep_leaf_tables(THD *thd);
 
   bool is_merged_child_of(st_select_lex *ancestor);
-  int print_explain(select_result_sink *output);
+  int print_explain(select_result_sink *output, uint8 explain_flags);
   /*
     For MODE_ONLY_FULL_GROUP_BY we need to maintain two flags:
      - Non-aggregated fields are used in this select.

sql/sql_select.cc

@@ -2123,6 +2123,14 @@ void JOIN::exec()
   */
   thd->apc_target.enable();
   exec_inner();
+
+  DBUG_EXECUTE_IF("show_explain_probe_join_exec_end", 
+                  if (dbug_user_var_equals_int(thd, 
+                                               "show_explain_probe_select_id", 
+                                               select_lex->select_number))
+                        dbug_serve_apcs(thd, 1);
+                 );
+
   thd->apc_target.disable();
 }
 
@@ -21075,7 +21083,7 @@ void JOIN::clear()
 
 
 int print_fake_select_lex_join(select_result_sink *result, bool on_the_fly,
-                               SELECT_LEX *select_lex, uint8 select_options)
+                               SELECT_LEX *select_lex, uint8 explain_flags)
 {
   const CHARSET_INFO *cs= system_charset_info;
   Item *item_null= new Item_null();
@@ -21121,7 +21129,7 @@ int print_fake_select_lex_join(select_result_sink *result, bool on_the_fly,
     item_list.push_back(new Item_string(table_name_buffer, len, cs));
   }
   /* partitions */
-  if (/*join->thd->lex->describe*/ select_options & DESCRIBE_PARTITIONS)
+  if (explain_flags & DESCRIBE_PARTITIONS)
     item_list.push_back(item_null);
   /* type */
   item_list.push_back(new Item_string(join_type_str[JT_ALL],
@@ -21136,7 +21144,7 @@ int print_fake_select_lex_join(select_result_sink *result, bool on_the_fly,
   /* ref */
   item_list.push_back(item_null);
   /* in_rows */
-  if (select_options & DESCRIBE_EXTENDED)
+  if (explain_flags & DESCRIBE_EXTENDED)
     item_list.push_back(item_null);
   /* rows */
   item_list.push_back(item_null);
@@ -21162,7 +21170,8 @@ int print_fake_select_lex_join(select_result_sink *result, bool on_the_fly,
                     modifications to any select's data structures
 */
 
-int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
+int JOIN::print_explain(select_result_sink *result, uint8 explain_flags,
+                         bool on_the_fly,
                          bool need_tmp_table, bool need_order,
                          bool distinct, const char *message)
 {
@@ -21199,9 +21208,9 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
 					strlen(join->select_lex->type), cs));
     for (uint i=0 ; i < 7; i++)
       item_list.push_back(item_null);
-    if (join->thd->lex->describe & DESCRIBE_PARTITIONS)
+    if (explain_flags & DESCRIBE_PARTITIONS)
       item_list.push_back(item_null);
-    if (join->thd->lex->describe & DESCRIBE_EXTENDED)
+    if (explain_flags & DESCRIBE_EXTENDED)
       item_list.push_back(item_null);
   
     item_list.push_back(new Item_string(message,strlen(message),cs));
@@ -21212,7 +21221,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
   {
     if (print_fake_select_lex_join(result, on_the_fly, 
                                    join->select_lex, 
-                                   join->thd->lex->describe))
+                                   explain_flags))
       error= 1;
   }
   else if (!join->select_lex->master_unit()->derived ||
@@ -21317,7 +21326,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
 					    cs));
       }
       /* "partitions" column */
-      if (join->thd->lex->describe & DESCRIBE_PARTITIONS)
+      if (explain_flags & DESCRIBE_PARTITIONS)
       {
 #ifdef WITH_PARTITION_STORAGE_ENGINE
         partition_info *part_info;
@@ -21460,7 +21469,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
           table_list->schema_table)
       {
         /* in_rows */
-        if (join->thd->lex->describe & DESCRIBE_EXTENDED)
+        if (explain_flags & DESCRIBE_EXTENDED)
           item_list.push_back(item_null);
         /* rows */
         item_list.push_back(item_null);
@@ -21497,7 +21506,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
                                          MY_INT64_NUM_DECIMAL_DIGITS));
 
         /* Add "filtered" field to item_list. */
-        if (join->thd->lex->describe & DESCRIBE_EXTENDED)
+        if (explain_flags & DESCRIBE_EXTENDED)
         {
           float f= 0.0; 
           if (examined_rows)
@@ -21577,7 +21586,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
             {
               extra.append(STRING_WITH_LEN("; Using where with pushed "
                                            "condition"));
-              if (thd->lex->describe & DESCRIBE_EXTENDED)
+              if (explain_flags & DESCRIBE_EXTENDED)
               {
                 extra.append(STRING_WITH_LEN(": "));
                 ((COND *)pushed_cond)->print(&extra, QT_ORDINARY);
@@ -21732,7 +21741,8 @@ static void select_describe(JOIN *join, bool need_tmp_table, bool need_order,
   THD *thd=join->thd;
   select_result *result=join->result;
   DBUG_ENTER("select_describe");
-  join->error= join->print_explain(result, FALSE, /* Not on-the-fly */
+  join->error= join->print_explain(result, thd->lex->describe, 
+                                   FALSE, /* Not on-the-fly */
                                    need_tmp_table, need_order, distinct, 
                                    message);
 

sql/sql_select.h

@@ -1405,7 +1405,8 @@ public:
     return (unit->item && unit->item->is_in_predicate());
   }
 
-  int print_explain(select_result_sink *result, bool on_the_fly,
+  int print_explain(select_result_sink *result, uint8 explain_flags,
+                     bool on_the_fly,
                      bool need_tmp_table, bool need_order,
                      bool distinct,const char *message);
 private: