feat(spanner/spansql): support JSON data type (#4959)

Co-authored-by: Rahul Yadav <irahul@google.com>
Co-authored-by: Hengfeng Li <hengfeng@google.com>

spanner/spannertest/README.md

@@ -19,6 +19,7 @@ by ascending esotericism:
 
 - expression functions
 - NUMERIC
+- JSON
 - more aggregation functions
 - SELECT HAVING
 - more literal types

spanner/spansql/parser.go

@@ -1890,6 +1890,7 @@ var baseTypes = map[string]TypeBase{
 	"BYTES":     Bytes,
 	"DATE":      Date,
 	"TIMESTAMP": Timestamp,
+	"JSON":      JSON,
 }
 
 func (p *parser) parseType() (Type, *parseError) {
@@ -1900,7 +1901,7 @@ func (p *parser) parseType() (Type, *parseError) {
 			ARRAY< scalar_type >
 
 		scalar_type:
-			{ BOOL | INT64 | FLOAT64 | NUMERIC | STRING( length ) | BYTES( length ) | DATE | TIMESTAMP }
+			{ BOOL | INT64 | FLOAT64 | NUMERIC | STRING( length ) | BYTES( length ) | DATE | TIMESTAMP | JSON }
 		length:
 			{ int64_value | MAX }
 	*/

spanner/spansql/sql.go

@@ -322,6 +322,8 @@ func (tb TypeBase) SQL() string {
 		return "DATE"
 	case Timestamp:
 		return "TIMESTAMP"
+	case JSON:
+		return "JSON"
 	}
 	panic("unknown TypeBase")
 }

spanner/spansql/sql_test.go

@@ -84,6 +84,7 @@ func TestSQL(t *testing.T) {
 					{Name: "Ck", Type: Type{Array: true, Base: String, Len: MaxLen}, Position: line(12)},
 					{Name: "Cl", Type: Type{Base: Timestamp}, Options: ColumnOptions{AllowCommitTimestamp: boolAddr(false)}, Position: line(13)},
 					{Name: "Cm", Type: Type{Base: Int64}, Generated: Func{Name: "CHAR_LENGTH", Args: []Expr{ID("Ce")}}, Position: line(14)},
+					{Name: "Cn", Type: Type{Base: JSON}, Position: line(15)},
 				},
 				PrimaryKey: []KeyPart{
 					{Column: "Ca"},
@@ -105,6 +106,7 @@ func TestSQL(t *testing.T) {
   Ck ARRAY<STRING(MAX)>,
   Cl TIMESTAMP OPTIONS (allow_commit_timestamp = null),
   Cm INT64 AS (CHAR_LENGTH(Ce)) STORED,
+  Cn JSON,
 ) PRIMARY KEY(Ca, Cb DESC)`,
 			reparseDDL,
 		},

spanner/spansql/types.go

@@ -387,6 +387,7 @@ const (
 	Bytes
 	Date
 	Timestamp
+	JSON
 )
 
 // KeyPart represents a column specification as part of a primary key or index definition.