parser: handle create table PARTITION BY KEY grammar (#4539)

parser/parser.y

@@ -1765,6 +1765,8 @@ DefaultKwdOpt:
 
 PartitionOpt:
 	{}
+|	"PARTITION" "BY" "KEY" '(' ColumnNameList ')' PartitionNumOpt PartitionDefinitionListOpt
+	{}
 |	"PARTITION" "BY" "HASH" '(' Expression ')' PartitionNumOpt PartitionDefinitionListOpt
 	{}
 |	"PARTITION" "BY" "RANGE" '(' Expression ')' PartitionNumOpt  PartitionDefinitionListOpt

parser/parser_test.go

@@ -1258,6 +1258,7 @@ func (s *testParserSuite) TestDDL(c *C) {
 		{"create table t (c int) PARTITION BY HASH (c) PARTITIONS 32;", true},
 		{"create table t (c int) PARTITION BY RANGE (Year(VDate)) (PARTITION p1980 VALUES LESS THAN (1980) ENGINE = MyISAM, PARTITION p1990 VALUES LESS THAN (1990) ENGINE = MyISAM, PARTITION pothers VALUES LESS THAN MAXVALUE ENGINE = MyISAM)", true},
 		{"create table t (c int, `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '') PARTITION BY RANGE (UNIX_TIMESTAMP(create_time)) (PARTITION p201610 VALUES LESS THAN(1477929600), PARTITION p201611 VALUES LESS THAN(1480521600),PARTITION p201612 VALUES LESS THAN(1483200000),PARTITION p201701 VALUES LESS THAN(1485878400),PARTITION p201702 VALUES LESS THAN(1488297600),PARTITION p201703 VALUES LESS THAN(1490976000))", true},
+		{"CREATE TABLE `md_product_shop` (`shopCode` varchar(4) DEFAULT NULL COMMENT '地点') ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 /*!50100 PARTITION BY KEY (shopCode) PARTITIONS 19 */;", true},
 
 		// for check clause
 		{"create table t (c1 bool, c2 bool, check (c1 in (0, 1)), check (c2 in (0, 1)))", true},