comb multi in predicate

[wy1433]

允许多个in组合条件命中索引
例如索引： key idx_abcd(a, b, c, d), 条件：a in ("a1", "a2") and (b , c) in (("b1", "c1"), ("b2","c2"))， 会匹配索引a,b,c三个字段
条件a全匹配被裁剪，条件(b, c)全部字段匹配索引索引被裁剪，裁剪后的条件会被组合展开为索引的ranges：

a1, b1, c1
a2, b1, c1
a1, b2, c2
a2, b2, c2

若一个字段对应多个in表达式，则只会使用一个，例如：(a , b) in (("a1", "b1"), ("a2","b2")) and (b , c) in (("b1", "c1"), ("b2","c2"), ("b3","c3"))， b字段同时对应了2个in条件，则b字段只会使用in的值较少的一个，本例为会使用(a,b)
(a,b)全部字段匹配索引将会被裁剪掉，(b, c)只会索引匹配字段c，条件会被保留，但记录("b3", "c3")将会被裁剪掉。索引的ranges将被展开为：

a1, b1, c1
a2, b2, c1
a1, b1, c2
a2, b2, c2

相关测试用例，可以用explain format='plan' select ... 进行分析：

CREATE TABLE `testin` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `a` varchar(1024) NOT NULL ,
  `b` varchar(1024) NOT NULL ,
  `c` varchar(1024) NOT NULL ,
  `d` varchar(1024) NOT NULL ,
  `e` varchar(1024) NOT NULL ,
  `f` varchar(1024) NOT NULL ,
  PRIMARY KEY (`id`),
  KEY idx_abcdef(`a`,`b`,`c`,`d`,`e`,`f`)
);
system sleep 30;

INSERT INTO testin VALUES(NULL, "a1", "b1", "c1", "d1", "e1", "f1");
INSERT INTO testin VALUES(NULL, "a2", "b2", "c2", "d2", "e2", "f2");
INSERT INTO testin VALUES(NULL, "a3", "b3", "c3", "d3", "e3", "f3");
INSERT INTO testin VALUES(NULL, "a4", "b4", "c4", "d4", "e4", "f4");
INSERT INTO testin VALUES(NULL, "a5", "b5", "c5", "d5", "e5", "f5");
INSERT INTO testin VALUES(NULL, "a6", "b6", "c6", "d6", "e6", "f6");

# 单in组合
select id from testin where a IN ("a1" , "a2") and b IN ("b1", "b2", "b3");
select id from testin where a IN ("a1" , "a2") and b IN ("b1", "b2", "b3")  and c IN ("c1", "c2") ;

# 单in与row_expr组合
select id from testin where  a in ("a1", "a2") and (b , c) in (("b1", "c1"), ("b2","c2"));

# row_expr组合
select id from testin where  (a , b) in (("a1", "b1"), ("a2","b2")) and (c , d) in (("c1", "d1"), ("c3","d3"));

# 字段有重叠
select id from testin where  a in ("a1", "a2") and (a , b) in (("a1", "b1"), ("a3","b3"));
select id from testin where  (a, b) IN (("a1", "b1")) and (b, c) IN (("b1","c1"));
select id from testin where  (a, b) IN (("a1", "b1")) and (b, c) IN (("b1","c2"));
select id from testin where  (a , b) in (("a1", "b1"), ("a2","b2")) and (b , c) in (("b1", "c1"), ("b2","c2"));
select id from testin where  (a , b) in (("a1", "b1"), ("a2","b2")) and (b , c) in (("b2", "c1"), ("b1","c2"));
select id from testin where  (a , b) in (("a1", "b1"), ("a2","b2")) and (b , c) in (("b1", "c1"), ("b2","c2"), ("b3","c3"));

select id from testin where (a , b) in (("a1", "b1"), ("a2","b1")) and (b , c) in (("b1", "c1"), ("b2","c2"), ("b3","c3"));
select id from testin where  (a, b) in ( ("a1","b1"),("a2","b1"),("a3","b2"),("a4","b2") ) and (b, c) in ( ("b1","c1"),("b1","c2"),("b2","c3"),("b2","c4"));
select id from testin where  a in ("a1", "a2", "a3") and (a , b) in (("a1", "b1"), ("a2","b2")) and (a, c) in (("a1", "c1"), ("a3","c3"))

# 多in组合与range组合
select id from testin where (a , b) in (("a1", "b1"), ("a2","b2")) and (b , c) in (("b1", "c1"), ("b2","c2"), ("b3","c3")) and d in ("d1","d2","d3","d4") and e > "e1" and e < "e4";

# Row Expr EQ
select id from testin where (a , b) = ("a1", "b1") and (b, a) = ("b1", "a2");
select id from testin where (a,b) = ("a1","b1") and (b,a) = ("b1","a1");
select id from testin where a = "a1" and b="b1" and (a , b) = ("a1", "b1");
select id from testin where a = "a1"  and (a , b) = ("a1", "b1");

# EQ IN Range组合
select id from testin where   a ="a1" and b in ("b1", "b2") and (b,c) in (("b1","c1"),("b2","c2")) and a < "a5" and (d, e) >= ("d1","e1");

[lgqss]

考虑：(a , b) in (("a1", "b1"), ("a2","b1")) and (b , c) in (("b1", "c1"), ("b2","c2"), ("b3","c3"))

a,b 是 a1,b1, a2,b1, a3,b2, a4,b2；b,c 是b1,c1, b1,c2, b2,c3, b2,c4