MCOL-4234: improve GROUP BY and ORDER BY interaction (#3194)

This patch fixes the problem in MCOL-4234 and also generally improves
behavior of GROUP BY.

It does so by introducing a "dummy" aggregate and by wrapping columns
into it. This allows for columns that are not in GROUP BY to be used
more freely, for example, in SELECT * FROM tbl GROUP BY col - all
columns that are not "col" will be wrapped into an aggregate and query
will proceed to execution.

The dummy aggregate itself does nothing more than remember last value
passed into it.

There also an additional error message that tries to explain what types
of expressions can be wrapped into an aggregate.

mysql-test/columnstore/basic/r/mcol-4525.result

@@ -80,7 +80,8 @@ SET columnstore_select_handler=ON;
 SELECT SUM(col1) AS col2 FROM t1 GROUP BY col2;
 ERROR 42000: The storage engine for the table doesn't support MCS-2016: Non supported item 'col2' on the GROUP BY list.
 SELECT col1 c FROM t1 ORDER BY AVG(col1);
-ERROR HY000: Internal error: MCS-2021: 'c' is not in GROUP BY clause. All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause.
+c
+10
 SET columnstore_select_handler=AUTO;
 SELECT SUM(col1) AS col2 FROM t1 GROUP BY col2;
 col2

mysql-test/columnstore/basic/r/mcs35_select_group_by.result

@@ -56,7 +56,9 @@ NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
 NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
 NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
 SELECT * FROM t1 GROUP BY t1_tinyint;
-ERROR HY000: Internal error: MCS-2021: '`mcs35_db1`.`t1`.`t1_int`' is not in GROUP BY clause. All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause.
+t1_tinyint	t1_int	t1_bigint	t1_double	t1_float	t1_blob	t1_text	t1_char	t1_varchar	t1_datetime
+0	NULL	403685477580676	54.797693231	8.40287	222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222	dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd	d	hello world!	4387-11-08 11:22:30
+NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
 SELECT COUNT(*) FROM t1 GROUP BY t1_tinyint;
 COUNT(*)
 11

mysql-test/columnstore/basic/r/mcs36_select_order_by_group_by.result

@@ -69,7 +69,11 @@ spID	userid	MIN(t1.score)
 3	3	3
 SELECT t1.spID, t2.userid, MIN(t1.score) 
 FROM t1, t2 WHERE t1.userID=t2.userID GROUP BY t2.userid, t1.spID ORDER BY t1.date;
-ERROR HY000: Internal error: MCS-2021: 'mcs36_db1.t1.date' is not in GROUP BY clause. All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause.
+spID	userid	MIN(t1.score)
+1	1	1
+2	1	1
+2	2	2
+3	3	3
 SELECT t2.userid, MIN(t1.score)
 FROM t1, t2 WHERE t1.userID=t2.userID GROUP BY unknown ORDER BY t2.userid;
 ERROR 42S22: Unknown column 'unknown' in 'group statement'
@@ -78,5 +82,20 @@ FROM t1, t2 WHERE t1.userID=t2.userID GROUP BY t2.userid ORDER BY unknown;
 ERROR 42S22: Unknown column 'unknown' in 'order clause'
 SELECT t2.userid, MIN(t1.score)
 FROM t1, t2 WHERE t1.userID=t2.userID GROUP BY t2.userid ORDER BY NULL;
-ERROR HY000: Internal error: MCS-2021: 'unknown db.unknown table.unknown field' is not in GROUP BY clause. All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause.
+userid	MIN(t1.score)
+1	1
+2	2
+3	3
+SELECT * FROM t1 GROUP BY spID, userID ORDER BY score ASC, spID, userID;
+spID	userID	score	lsg	date
+1	1	1		0000-00-00
+2	1	1		0000-00-00
+2	2	2		0000-00-00
+3	3	3		0000-00-00
+SELECT * FROM t1 GROUP BY spID, userID ORDER BY score DESC, spID, userID;
+spID	userID	score	lsg	date
+3	3	3		0000-00-00
+2	2	2		0000-00-00
+1	1	1		0000-00-00
+2	1	1		0000-00-00
 DROP DATABASE IF EXISTS mcs36_db1;

mysql-test/columnstore/basic/r/mcs76_having.result

@@ -23,7 +23,9 @@ col1	col2
 3	sss
 4	ooo
 SELECT col1, col2, SUM(LENGTH(col2)) FROM t1 GROUP BY col1 HAVING col1 > 1 AND col2 LIKE '%o%' ORDER BY col1;
-ERROR HY000: Internal error: MCS-2021: '`mcs76_db`.`t1`.`col2`' is not in GROUP BY clause. All non-aggregate columns in the SELECT and ORDER BY clause must be included in the GROUP BY clause.
+col1	col2	SUM(LENGTH(col2))
+2	oooooooooooooooooooo	40
+4	ooo	6
 CREATE TABLE t2(col1 INT, col2 DATETIME)ENGINE=Columnstore;
 INSERT INTO t2 VALUES(1, '2020-2-2'),(2, '2020-3-3'),(5,'2020-6-6'),(6, '2020-7-7');
 SELECT t1.col1, SUM(t1.col1*t2.col1) AS a FROM t1 JOIN t2 ON t1.col1 = t2.col1 GROUP BY t1.col1 HAVING a>1 ORDER BY t1.col1;