EXPLAIN UNION using same routing which used for execution which allow return correct bug messages (Bug #3639)

EXPLAIN of hidden SELECT of UNION


mysql-test/r/derived.result:
  explain of hidden select
mysql-test/r/subselect.result:
  explain of hidden select
mysql-test/r/union.result:
  explain of hidden select
  correct error messages on explain
mysql-test/t/subselect.test:
  show eliminated costants in WHERE clause
mysql-test/t/union.test:
  correct error messages on EXPLAIN with union
sql/item.cc:
  fixed name constructing for global ORDER BY items
sql/sql_class.h:
  select ID can be negative (for hidden SELECTs)
  removed unused field
sql/sql_lex.cc:
  new flag of UNION EXPLAIN
sql/sql_lex.h:
  new flag of UNION EXPLAIN
  select ID can be negative (for hidden SELECTs)
sql/sql_select.cc:
  EXPLAIN UNION using same routing which used for execution
  explain for hidden SELECT of UNION
sql/sql_union.cc:
  EXPLAIN UNION using same routing which used for execution

1 files changed, 1 insertions, 2 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index d5eb7a9fd0e..af0fff4435a 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -768,7 +768,7 @@ public:
   uint	     current_tablenr,tmp_table;
   uint	     server_status,open_options,system_thread;
   uint32     db_length;
-  uint       select_number;             //number of select (used for EXPLAIN)
+  int        select_number;             //number of select (used for EXPLAIN)
   /* variables.transaction_isolation is reset to this after each commit */
   enum_tx_isolation session_tx_isolation;
   enum_check_fields count_cuted_fields;
@@ -1147,7 +1147,6 @@ class select_union :public select_result {
   TABLE *table;
   COPY_INFO info;
   TMP_TABLE_PARAM tmp_table_param;
-  bool not_describe;
 
   select_union(TABLE *table_par);
   ~select_union();