Auto-merged fix for the bug#30302.

mysql-test/r/explain.result

@@ -64,7 +64,7 @@ explain extended select * from v1 where f2=1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select '1' AS `f1`,'1' AS `f2` from `test`.`t1` where 1
+Note	1003	select '1' AS `f1`,'1' AS `f2` from dual where 1
 explain extended select * from t1 where 0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
@@ -74,7 +74,7 @@ explain extended select * from t1 where 1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select '1' AS `f1`,'1' AS `f2` from `test`.`t1` where 1
+Note	1003	select '1' AS `f1`,'1' AS `f2` from dual where 1
 explain extended select * from t1 having 0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible HAVING
@@ -84,7 +84,7 @@ explain extended select * from t1 having 1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select '1' AS `f1`,'1' AS `f2` from `test`.`t1` having 1
+Note	1003	select '1' AS `f1`,'1' AS `f2` from dual having 1
 drop view v1;
 drop table t1;
 CREATE TABLE t1(c INT);
@@ -194,4 +194,24 @@ dt
 2001-01-01 01:01:01
 2001-01-01 01:01:01
 drop tables t1, t2;
+#
+# Bug#30302: Tables that were optimized away are printed in the
+#            EXPLAIN EXTENDED warning.
+#
+create table t1(f1 int);
+create table t2(f2 int);
+insert into t1 values(1);
+insert into t2 values(1),(2);
+explain extended select * from t1 where f1=1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
+Warnings:
+Note	1003	select '1' AS `f1` from dual where 1
+explain extended select * from t1 join t2 on f1=f2 where f1=1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select '1' AS `f1`,`test`.`t2`.`f2` AS `f2` from `test`.`t2` where (`test`.`t2`.`f2` = 1)
+drop table t1,t2;
 End of 5.1 tests.

mysql-test/r/func_default.result

@@ -8,7 +8,7 @@ explain extended select default(str), default(strnull), default(intg), default(r
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select default('') AS `default(str)`,default('') AS `default(strnull)`,default('0') AS `default(intg)`,default('0') AS `default(rel)` from `test`.`t1`
+Note	1003	select default('') AS `default(str)`,default('') AS `default(strnull)`,default('0') AS `default(intg)`,default('0') AS `default(rel)` from dual
 select * from t1 where str <> default(str);
 str	strnull	intg	rel
 		0	0

mysql-test/r/func_regexp.result

@@ -52,7 +52,7 @@ explain extended select * from t1 where xxx regexp('is a test of some long text
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select 'this is a test of some long text to see what happens' AS `xxx` from `test`.`t1` where ('this is a test of some long text to see what happens' regexp 'is a test of some long text to')
+Note	1003	select 'this is a test of some long text to see what happens' AS `xxx` from dual where ('this is a test of some long text to see what happens' regexp 'is a test of some long text to')
 select * from t1 where xxx regexp('is a test of some long text to ');
 xxx
 this is a test of some long text to see what happens

mysql-test/r/func_test.result

@@ -87,7 +87,7 @@ explain extended select - a from t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select -('1') AS `- a` from `test`.`t1`
+Note	1003	select -('1') AS `- a` from dual
 drop table t1;
 select 5 between 0 and 10 between 0 and 1,(5 between 0 and 10) between 0 and 1;
 5 between 0 and 10 between 0 and 1	(5 between 0 and 10) between 0 and 1

mysql-test/r/having.result

@@ -12,7 +12,7 @@ explain extended select count(a) as b from t1 where a=0 having b >=0;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE noticed after reading const tables
 Warnings:
-Note	1003	select count('0') AS `b` from `test`.`t1` where 0 having (`b` >= 0)
+Note	1003	select count('0') AS `b` from dual where 0 having (`b` >= 0)
 drop table t1;
 CREATE TABLE t1 (
 raw_id int(10) NOT NULL default '0',

mysql-test/r/select.result

@@ -4435,7 +4435,7 @@ EXPLAIN EXTENDED SELECT * FROM t1 WHERE (a=a AND a=a) OR b > 2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	select '1' AS `a`,'1' AS `b` from `test`.`t1` where 1
+Note	1003	select '1' AS `a`,'1' AS `b` from dual where 1
 SELECT * FROM t1 WHERE (a=a AND a=a) OR b > 2;
 a	b
 1	1

mysql-test/r/subselect.result

@@ -50,7 +50,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 Warnings:
 Note	1276	Field or reference 'b.a' of SELECT #3 was resolved in SELECT #1
 Note	1276	Field or reference 'b.a' of SELECT #3 was resolved in SELECT #1
-Note	1003	select 1 AS `1` from (select 1 AS `a`) `b` having ((select '1' AS `a`) = 1)
+Note	1003	select 1 AS `1` from dual having ((select '1' AS `a`) = 1)
 SELECT 1 FROM (SELECT 1 as a) as b HAVING (SELECT a)=1;
 1
 1
@@ -203,7 +203,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 3	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
 2	SUBQUERY	t3	ALL	NULL	NULL	NULL	NULL	3	100.00	Using where; Using filesort
 Warnings:
-Note	1003	select (select `test`.`t3`.`a` AS `a` from `test`.`t3` where (`test`.`t3`.`a` < 8) order by 1 desc limit 1) AS `(select t3.a from t3 where a<8 order by 1 desc limit 1)`,'2' AS `a` from (select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b` from `test`.`t2` where (`test`.`t2`.`a` > 1)) `tt`
+Note	1003	select (select `test`.`t3`.`a` AS `a` from `test`.`t3` where (`test`.`t3`.`a` < 8) order by 1 desc limit 1) AS `(select t3.a from t3 where a<8 order by 1 desc limit 1)`,'2' AS `a` from dual
 select * from t1 where t1.a=(select t2.a from t2 where t2.b=(select max(a) from t3) order by 1 desc limit 1);
 a
 2
@@ -314,7 +314,7 @@ NULL	UNION RESULT	<union2,3>	ALL	NULL	NULL	NULL	NULL	NULL	NULL
 Warnings:
 Note	1276	Field or reference 'test.t2.a' of SELECT #2 was resolved in SELECT #1
 Note	1276	Field or reference 'test.t2.a' of SELECT #3 was resolved in SELECT #1
-Note	1003	select (select '2' AS `a` from `test`.`t1` where ('2' = `test`.`t2`.`a`) union select `test`.`t5`.`a` AS `a` from `test`.`t5` where (`test`.`t5`.`a` = `test`.`t2`.`a`)) AS `(select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a)`,`test`.`t2`.`a` AS `a` from `test`.`t2`
+Note	1003	select (select '2' AS `a` from dual where ('2' = `test`.`t2`.`a`) union select `test`.`t5`.`a` AS `a` from `test`.`t5` where (`test`.`t5`.`a` = `test`.`t2`.`a`)) AS `(select a from t1 where t1.a=t2.a union select a from t5 where t5.a=t2.a)`,`test`.`t2`.`a` AS `a` from `test`.`t2`
 select (select a from t1 where t1.a=t2.a union all select a from t5 where t5.a=t2.a), a from t2;
 ERROR 21000: Subquery returns more than 1 row
 create table t6 (patient_uq int, clinic_uq int, index i1 (clinic_uq));
@@ -1429,7 +1429,7 @@ explain extended (select * from t1);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 1	SIMPLE	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 Warnings:
-Note	1003	(select 'tttt' AS `s1` from `test`.`t1`)
+Note	1003	(select 'tttt' AS `s1` from dual)
 (select * from t1);
 s1
 tttt
@@ -1617,7 +1617,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 3	UNION	t1	system	NULL	NULL	NULL	NULL	1	100.00	
 NULL	UNION RESULT	<union2,3>	ALL	NULL	NULL	NULL	NULL	NULL	NULL	
 Warnings:
-Note	1003	select 'e' AS `s1` from `test`.`t1` where 1
+Note	1003	select 'e' AS `s1` from dual where 1
 drop table t1;
 CREATE TABLE t1 (number char(11) NOT NULL default '') ENGINE=MyISAM CHARSET=latin1;
 INSERT INTO t1 VALUES ('69294728265'),('18621828126'),('89356874041'),('95895001874');

mysql-test/r/subselect3.result

@@ -864,7 +864,7 @@ Level	Code	Message
 Note	1276	Field or reference 'test.t1.a' of SELECT #3 was resolved in SELECT #2
 Note	1276	Field or reference 'test.t1.c' of SELECT #3 was resolved in SELECT #2
 Error	1054	Unknown column 'c' in 'field list'
-Note	1003	select `c` AS `c` from (select (select count(`test`.`t1`.`a`) AS `COUNT(a)` from (select count(`test`.`t1`.`b`) AS `COUNT(b)` from `test`.`t1`) `x` group by `c`) AS `(SELECT COUNT(a) FROM 
+Note	1003	select `c` AS `c` from (select (select count(`test`.`t1`.`a`) AS `COUNT(a)` from dual group by `c`) AS `(SELECT COUNT(a) FROM 
 (SELECT COUNT(b) FROM t1) AS x GROUP BY c
 )` from `test`.`t1` group by `test`.`t1`.`b`) `y`
 DROP TABLE t1;

mysql-test/r/type_datetime.result

@@ -517,7 +517,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 2	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
 Warnings:
 Note	1276	Field or reference 'test.t1.cur_date' of SELECT #2 was resolved in SELECT #1
-Note	1003	select '1' AS `id`,'2007-04-25 18:30:22' AS `cur_date` from `test`.`t1` where <in_optimizer>('1',<exists>(select 1 AS `Not_used` from `test`.`t1` `x1` where 0))
+Note	1003	select '1' AS `id`,'2007-04-25 18:30:22' AS `cur_date` from dual where <in_optimizer>('1',<exists>(select 1 AS `Not_used` from `test`.`t1` `x1` where 0))
 select * from t1
 where id in (select id from t1 as x1 where (t1.cur_date is null));
 id	cur_date
@@ -529,7 +529,7 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
 2	DEPENDENT SUBQUERY	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Impossible WHERE
 Warnings:
 Note	1276	Field or reference 'test.t2.cur_date' of SELECT #2 was resolved in SELECT #1
-Note	1003	select '1' AS `id`,'2007-04-25' AS `cur_date` from `test`.`t2` where <in_optimizer>('1',<exists>(select 1 AS `Not_used` from `test`.`t2` `x1` where 0))
+Note	1003	select '1' AS `id`,'2007-04-25' AS `cur_date` from dual where <in_optimizer>('1',<exists>(select 1 AS `Not_used` from `test`.`t2` `x1` where 0))
 select * from t2
 where id in (select id from t2 as x1 where (t2.cur_date is null));
 id	cur_date

mysql-test/t/explain.test

@@ -167,4 +167,16 @@ flush tables;
 SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' );
 drop tables t1, t2;
 
+
+--echo #
+--echo # Bug#30302: Tables that were optimized away are printed in the
+--echo #            EXPLAIN EXTENDED warning.
+--echo #
+create table t1(f1 int);
+create table t2(f2 int);
+insert into t1 values(1);
+insert into t2 values(1),(2);
+explain extended select * from t1 where f1=1;
+explain extended select * from t1 join t2 on f1=f2 where f1=1;
+drop table t1,t2;
 --echo End of 5.1 tests.

sql/sql_select.cc

@@ -2668,7 +2668,10 @@ make_join_statistics(JOIN *join, TABLE_LIST *tables_arg, COND *conds,
 	goto error;		// Fatal error
     }
     else
+    {
       found_const_table_map|= s->table->map;
+      s->table->pos_in_table_list->optimized_away= TRUE;
+    }
   }
 
   /* loop until no more const tables are found */
@@ -16564,18 +16567,35 @@ static void print_join(THD *thd,
 {
   /* List is reversed => we should reverse it before using */
   List_iterator_fast<TABLE_LIST> ti(*tables);
-  TABLE_LIST **table= (TABLE_LIST **)thd->alloc(sizeof(TABLE_LIST*) *
-                                                tables->elements);
-  if (table == 0)
+  TABLE_LIST **table;
+  uint non_const_tables= 0;
+
+  for (TABLE_LIST *t= ti++; t ; t= ti++)
+    if (!t->optimized_away)
+      non_const_tables++;
+  if (!non_const_tables)
+  {
+    str->append(STRING_WITH_LEN("dual"));
+    return; // all tables were optimized away
+  }
+  ti.rewind();
+
+  if (!(table= (TABLE_LIST **)thd->alloc(sizeof(TABLE_LIST*) *
+                                                non_const_tables)))
     return;  // out of memory
 
-  for (TABLE_LIST **t= table + (tables->elements - 1); t >= table; t--)
-    *t= ti++;
+  TABLE_LIST *tmp, **t= table + (non_const_tables - 1);
+  while ((tmp= ti++))
+  {
+    if (tmp->optimized_away)
+      continue;
+    *t--= tmp;
+  }
 
   DBUG_ASSERT(tables->elements >= 1);
   (*table)->print(thd, str, query_type);
 
-  TABLE_LIST **end= table + tables->elements;
+  TABLE_LIST **end= table + non_const_tables;
   for (TABLE_LIST **tbl= table + 1; tbl < end; tbl++)
   {
     TABLE_LIST *curr= *tbl;

sql/table.h

@@ -1356,6 +1356,8 @@ struct TABLE_LIST
     the parsed tree is created.
   */
   uint8 trg_event_map;
+  /* TRUE <=> this table is a const one and was optimized away. */
+  bool optimized_away;
 
   uint i_s_requested_object;
   bool has_db_lookup_value;