slack-15.0: backport vitessio/vitess#16106

go/test/endtoend/utils/cmp.go

@@ -19,7 +19,6 @@ package utils
 import (
 	"context"
 	"fmt"
-	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/stretchr/testify/assert"
@@ -30,12 +29,17 @@ import (
 	"vitess.io/vitess/go/test/utils"
 )
 
+type TestingT interface {
+	require.TestingT
+	Helper()
+}
+
 type MySQLCompare struct {
-	t                 *testing.T
+	t                 TestingT
 	MySQLConn, VtConn *mysql.Conn
 }
 
-func NewMySQLCompare(t *testing.T, vtParams, mysqlParams mysql.ConnParams) (MySQLCompare, error) {
+func NewMySQLCompare(t TestingT, vtParams, mysqlParams mysql.ConnParams) (MySQLCompare, error) {
 	ctx := context.Background()
 	vtConn, err := mysql.Connect(ctx, &vtParams)
 	if err != nil {

go/test/endtoend/utils/mysql.go

@@ -21,7 +21,6 @@
 	"fmt"
 	"os"
 	"path"
-	"testing"
 
 	"github.com/stretchr/testify/assert"
 
@@ -132,16 +131,16 @@
 	return nil
 }
 
-func compareVitessAndMySQLResults(t *testing.T, query string, vtQr, mysqlQr *sqltypes.Result, compareColumns bool) {
+func compareVitessAndMySQLResults(t TestingT, query string, vtQr, mysqlQr *sqltypes.Result, compareColumns bool) {
 	if vtQr == nil && mysqlQr == nil {
 		return
 	}
 	if vtQr == nil {
 		t.Error("Vitess result is 'nil' while MySQL's is not.")
 		return
 	}
 	if mysqlQr == nil {
 		t.Error("MySQL result is 'nil' while Vitess' is not.")
 		return
 	}
 	if compareColumns {
@@ -163,7 +162,7 @@
 	}
 	stmt, err := sqlparser.Parse(query)
 	if err != nil {
 		t.Error(err)
 		return
 	}
 	orderBy := false
@@ -185,13 +184,13 @@
 	for _, row := range mysqlQr.Rows {
 		errStr += fmt.Sprintf("%s\n", row)
 	}
 	t.Error(errStr)
 }
 
-func compareVitessAndMySQLErrors(t *testing.T, vtErr, mysqlErr error) {
+func compareVitessAndMySQLErrors(t TestingT, vtErr, mysqlErr error) {
 	if vtErr != nil && mysqlErr != nil || vtErr == nil && mysqlErr == nil {
 		return
 	}
 	out := fmt.Sprintf("Vitess and MySQL are not erroring the same way.\nVitess error: %v\nMySQL error: %v", vtErr, mysqlErr)
 	t.Error(out)
 }

go/test/endtoend/vtgate/gen4/gen4_test.go

@@ -495,3 +495,15 @@ func TestFilterOnLeftOuterJoin(t *testing.T) {
 
 	mcmp.AssertMatches(query, "[[INT32(22)] [INT32(33)]]")
 }
+
+func BenchmarkCountStar(b *testing.B) {
+	mcmp, closer := start(b)
+	defer closer()
+
+	// insert some data.
+	mcmp.Exec(`insert into t2(id, tcol1, tcol2) values (1, 'A%B', 'A%B'),(2, 'C_D', 'E'),(3, 'AB', 'C1D'),(4, 'E', 'A%B'),(5, 'A%B', 'AB'),(6, 'C1D', 'E'),(7, 'C_D', 'A%B'),(8, 'E', 'C_D')`)
+
+	for i := 0; i < b.N; i++ {
+		mcmp.Exec(`select Count(*) from t2`)
+	}
+}

go/test/endtoend/vtgate/gen4/main_test.go

@@ -135,7 +135,7 @@ func TestMain(m *testing.M) {
 	os.Exit(exitCode)
 }
 
-func start(t *testing.T) (utils.MySQLCompare, func()) {
+func start(t testing.TB) (utils.MySQLCompare, func()) {
 	mcmp, err := utils.NewMySQLCompare(t, vtParams, mysqlParams)
 	require.NoError(t, err)
 	deleteAll := func() {

go/vt/sqlparser/ast_funcs.go

@@ -654,6 +654,24 @@ func NewColNameWithQualifier(identifier string, table TableName) *ColName {
 	}
 }
 
+func createAliasForEmpty(selectExpr SelectExpr, alias string) {
+	switch node := selectExpr.(type) {
+	case *AliasedExpr:
+		// The check here to see if the select expression printed as a string matches the alias exactly
+		// is an optimization to remove the aliases that are not required.
+		// That being said, removing this optimization will actually fix a few more queries that give incorrect column names,
+		// like `SELECT 1`. With this optimization the parser doesn't add an alias, so vtgate runs this query after normalization
+		// as `SELECT :vtg1` and therefore produces the wrong column name. If the column name is required to be correct, then there are
+		// 2 possible fixes -
+		// 1. Remove this check, so that parser changes the query to `SELECT 1 as `1`` and even after normalizing, it will remain `SELECT :vtg1 as `1``
+		// so the alias would be correct.
+		// 2. The other fix is to prevent the normalization of literals in select expressions altogether, in which case this optimization can be kept.
+		if node.As.IsEmpty() && String(selectExpr) != strings.TrimSpace(alias) {
+			node.As = NewIdentifierCI(strings.TrimSpace(alias))
+		}
+	}
+}
+
 // NewSelect is used to create a select statement
 func NewSelect(comments Comments, exprs SelectExprs, selectOptions []string, into *SelectInto, from TableExprs, where *Where, groupBy GroupBy, having *Where, windows NamedWindows) *Select {
 	var cache *bool

go/vt/sqlparser/parse_test.go

@@ -5294,8 +5294,8 @@ func TestOne(t *testing.T) {
 	testOne := struct {
 		input, output string
 	}{
-		input:  "",
-		output: "",
+		input:  "select cOlUmN_NaME, 1+   2, 1, CoUnT ( *  ) from t1",
+		output: "select cOlUmN_NaME, 1 + 2 as `1+   2`, 1, count(*) as `CoUnT ( *  )` from t1",
 	}
 	if testOne.input == "" {
 		return