Fix parsing of PARTITION BY KEY (vitessio#10958) (vitessio#932)

* Fix parsing of `PARTITION BY KEY`

The `PARTITION BY KEY` syntax allows for passing in an empty column list
which signifies that the primary key is used for partitioning.

This needs to be added to the parser to support this case.

See also https://dev.mysql.com/doc/refman/8.0/en/partitioning-key.html

Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>

* Simplify parser

Signed-off-by: Dirkjan Bussink <d.bussink@gmail.com>

go/vt/sqlparser/ast_format.go

@@ -568,7 +568,11 @@ func (node *PartitionOption) Format(buf *TrackedBuffer) {
 		if node.KeyAlgorithm != 0 {
 			buf.astPrintf(node, " algorithm = %d", node.KeyAlgorithm)
 		}
-		buf.astPrintf(node, " %v", node.ColList)
+		if len(node.ColList) == 0 {
+			buf.literal(" ()")
+		} else {
+			buf.astPrintf(node, " %v", node.ColList)
+		}
 	case RangeType, ListType:
 		buf.astPrintf(node, " %s", node.Type.ToString())
 		if node.Expr != nil {
@@ -611,7 +615,11 @@ func (node *SubPartition) Format(buf *TrackedBuffer) {
 		if node.KeyAlgorithm != 0 {
 			buf.astPrintf(node, " algorithm = %d", node.KeyAlgorithm)
 		}
-		buf.astPrintf(node, " %v", node.ColList)
+		if len(node.ColList) == 0 {
+			buf.literal(" ()")
+		} else {
+			buf.astPrintf(node, " %v", node.ColList)
+		}
 	}
 
 	if node.SubPartitions != -1 {

go/vt/sqlparser/parse_test.go

@@ -1488,6 +1488,9 @@ var (
 	}, {
 		input:  "create table t (id int) partition by key (id) partitions 2",
 		output: "create table t (\n\tid int\n)\npartition by key (id) partitions 2",
+	}, {
+		input:  "create table t (id int, primary key(id)) partition by key () partitions 2",
+		output: "create table t (\n\tid int,\n\tprimary key (id)\n)\npartition by key () partitions 2",
 	}, {
 		input:  "create table t (id int) partition by key algorithm = 1 (id)",
 		output: "create table t (\n\tid int\n)\npartition by key algorithm = 1 (id)",