Add EXPLAIN format for Vitess plans

go/vt/sqlparser/analyzer.go

@@ -52,6 +52,7 @@ const (
 	StmtUnknown
 	StmtComment
 	StmtPriv
+	StmtExplain
 )
 
 //ASTToStatementType returns a StatementType from an AST stmt
@@ -75,6 +76,8 @@ func ASTToStatementType(stmt Statement) StatementType {
 		return StmtUse
 	case *OtherRead, *OtherAdmin:
 		return StmtOther
+	case *Explain:
+		return StmtExplain
 	case *Begin:
 		return StmtBegin
 	case *Commit:
@@ -158,7 +161,9 @@ func Preview(sql string) StatementType {
 		return StmtShow
 	case "use":
 		return StmtUse
-	case "analyze", "describe", "desc", "explain", "repair", "optimize":
+	case "describe", "desc", "explain":
+		return StmtExplain
+	case "analyze", "repair", "optimize":
 		return StmtOther
 	case "grant", "revoke":
 		return StmtPriv
@@ -198,6 +203,8 @@ func (s StatementType) String() string {
 		return "OTHER"
 	case StmtPriv:
 		return "PRIV"
+	case StmtExplain:
+		return "EXPLAIN"
 	default:
 		return "UNKNOWN"
 	}

go/vt/sqlparser/analyzer_test.go

@@ -66,9 +66,9 @@ func TestPreview(t *testing.T) {
 		{"show", StmtShow},
 		{"use", StmtUse},
 		{"analyze", StmtOther},
-		{"describe", StmtOther},
-		{"desc", StmtOther},
-		{"explain", StmtOther},
+		{"describe", StmtExplain},
+		{"desc", StmtExplain},
+		{"explain", StmtExplain},
 		{"repair", StmtOther},
 		{"optimize", StmtOther},
 		{"grant", StmtPriv},

go/vt/sqlparser/ast.go

@@ -227,6 +227,12 @@ type (
 	// Rollback represents a Rollback statement.
 	Rollback struct{}
 
+	// Explain represents an EXPLAIN statement
+	Explain struct {
+		Type      string
+		Statement Statement
+	}
+
 	// OtherRead represents a DESCRIBE, or EXPLAIN statement.
 	// It should be used only as an indicator. It does not contain
 	// the full AST for the statement.
@@ -254,6 +260,7 @@ func (*Use) iStatement()               {}
 func (*Begin) iStatement()             {}
 func (*Commit) iStatement()            {}
 func (*Rollback) iStatement()          {}
+func (*Explain) iStatement()           {}
 func (*OtherRead) iStatement()         {}
 func (*OtherAdmin) iStatement()        {}
 func (*Select) iSelectStatement()      {}
@@ -1295,6 +1302,19 @@ func (node *Rollback) Format(buf *TrackedBuffer) {
 	buf.WriteString("rollback")
 }
 
+// Format formats the node.
+func (node *Explain) Format(buf *TrackedBuffer) {
+	format := ""
+	switch node.Type {
+	case "": // do nothing
+	case AnalyzeStr:
+		format = AnalyzeStr + " "
+	default:
+		format = "format = " + node.Type + " "
+	}
+	buf.astPrintf(node, "explain %s%v", format, node.Statement)
+}
+
 // Format formats the node.
 func (node *OtherRead) Format(buf *TrackedBuffer) {
 	buf.WriteString("otherread")

go/vt/sqlparser/constants.go

@@ -163,4 +163,11 @@ const (
 
 	TxReadOnly  = "read only"
 	TxReadWrite = "read write"
+
+	// Explain formats
+	TreeStr        = "tree"
+	JSONStr        = "json"
+	VitessStr      = "vitess"
+	TraditionalStr = "traditional"
+	AnalyzeStr     = "analyze"
 )

go/vt/sqlparser/parse_test.go

@@ -1373,14 +1373,41 @@ var (
 		input:  "use ks@replica",
 		output: "use `ks@replica`",
 	}, {
-		input:  "describe foobar",
-		output: "otherread",
+		input:  "describe select * from t",
+		output: "explain select * from t",
+	}, {
+		input:  "desc select * from t",
+		output: "explain select * from t",
 	}, {
 		input:  "desc foobar",
 		output: "otherread",
 	}, {
-		input:  "explain foobar",
+		input:  "explain t1",
+		output: "otherread",
+	}, {
+		input:  "explain t1 col",
 		output: "otherread",
+	}, {
+		input: "explain select * from t",
+	}, {
+		input: "explain format = traditional select * from t",
+	}, {
+		input: "explain analyze select * from t",
+	}, {
+		input: "explain format = tree select * from t",
+	}, {
+		input: "explain format = json select * from t",
+	}, {
+		input: "explain format = vitess select * from t",
+	}, {
+		input:  "describe format = vitess select * from t",
+		output: "explain format = vitess select * from t",
+	}, {
+		input: "explain delete from t",
+	}, {
+		input: "explain insert into t(col1, col2) values (1, 2)",
+	}, {
+		input: "explain update t set col = 2",
 	}, {
 		input:  "truncate table foo",
 		output: "truncate table foo",
@@ -1607,7 +1634,7 @@ func TestValid(t *testing.T) {
 				tcase.output = tcase.input
 			}
 			tree, err := Parse(tcase.input)
-			require.NoError(t, err)
+			require.NoError(t, err, tcase.input)
 			out := String(tree)
 			if diff := cmp.Diff(tcase.output, out); diff != "" {
 				t.Errorf("Parse(%q):\n%s", tcase.input, diff)