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, 12 insertions, 0 deletions

diff --git a/mysql-test/t/union.test b/mysql-test/t/union.test
index d9e19571f81..f6006a87d47 100644
--- a/mysql-test/t/union.test
+++ b/mysql-test/t/union.test
@@ -39,8 +39,11 @@ explain select a,b from t1 union all select a,b from t2;
 
 --error  1054
 explain select xx from t1 union select 1;
+--error 1222
 explain select a,b from t1 union select 1;
+--error 1222
 explain select 1 union select a,b from t1 union select 1;
+--error 1222
 explain select a,b from t1 union select 1 limit 0;
 
 --error 1221
@@ -515,3 +518,12 @@ SET SQL_SELECT_LIMIT=1;
 select a from t1 union select a from t2 order by a;
 drop table t1, t2;
 set sql_select_limit=default;
+
+#
+# nonexisting column in global ORDER BY
+#
+CREATE TABLE t1 (i int(11) default NULL,c char(1) default NULL,KEY i (i));
+CREATE TABLE t2 (i int(11) default NULL,c char(1) default NULL,KEY i (i));
+--error 1054
+explain (select * from t1) union (select * from t2) order by not_existing_column;
+drop table t1, t2;