bug: DML_SUBQUERY should suppress index hints

data/test/tabletserver/exec_cases.txt

@@ -908,6 +908,18 @@ options:PassthroughDMLs
   "WhereClause": " where eid = 1"
 }
 
+# update with index hint
+# note that you won't find a corresponding test for delete because the grammar doesn't allow it.
+"update a use index(b) set name = 'foo' where eid=1"
+{
+  "PlanID": "DML_SUBQUERY",
+  "TableName": "a",
+  "FullQuery": "update a use index (b) set name = 'foo' where eid = 1",
+  "OuterQuery": "update a set name = 'foo' where :#pk",
+  "Subquery": "select eid, id from a use index (b) where eid = 1 limit :#maxLimit for update",
+  "WhereClause": " where eid = 1"
+}
+
 # delete limit with pk
 "delete from d where name in ('a', 'b') limit 1"
 {

go/vt/sqlparser/ast.go

@@ -1383,6 +1383,13 @@ func (node *AliasedTableExpr) WalkSubtree(visit Visit) error {
 	)
 }
 
+// RemoveHints returns a new AliasedTableExpr with the hints removed.
+func (node *AliasedTableExpr) RemoveHints() *AliasedTableExpr {
+	noHints := *node
+	noHints.Hints = nil
+	return &noHints
+}
+
 // SimpleTableExpr represents a simple table expression.
 type SimpleTableExpr interface {
 	iSimpleTableExpr()

go/vt/sqlparser/ast_test.go

@@ -109,6 +109,22 @@ func TestSelect(t *testing.T) {
 	}
 }
 
+func TestRemoveHints(t *testing.T) {
+	tree, err := Parse("select * from t use index (i)")
+	if err != nil {
+		t.Fatal(err)
+	}
+	sel := tree.(*Select)
+	sel.From = TableExprs{
+		sel.From[0].(*AliasedTableExpr).RemoveHints(),
+	}
+	buf := NewTrackedBuffer(nil)
+	sel.Format(buf)
+	if got, want := buf.String(), "select * from t"; got != want {
+		t.Errorf("stripped query: %s, want %s", got, want)
+	}
+}
+
 func TestAddOrder(t *testing.T) {
 	src, err := Parse("select foo, bar from baz order by foo")
 	if err != nil {

go/vt/vttablet/tabletserver/planbuilder/dml.go

@@ -20,10 +20,11 @@ import (
 	log "github.com/golang/glog"
 
 	"github.com/youtube/vitess/go/sqltypes"
-	vtrpcpb "github.com/youtube/vitess/go/vt/proto/vtrpc"
 	"github.com/youtube/vitess/go/vt/sqlparser"
 	"github.com/youtube/vitess/go/vt/vterrors"
 	"github.com/youtube/vitess/go/vt/vttablet/tabletserver/schema"
+
+	vtrpcpb "github.com/youtube/vitess/go/vt/proto/vtrpc"
 )
 
 func analyzeUpdate(upd *sqlparser.Update, tables map[string]*schema.Table) (plan *Plan, err error) {
@@ -77,7 +78,7 @@ func analyzeUpdate(upd *sqlparser.Update, tables map[string]*schema.Table) (plan
 		return nil, err
 	}
 
-	plan.OuterQuery = GenerateUpdateOuterQuery(upd, nil)
+	plan.OuterQuery = GenerateUpdateOuterQuery(upd, aliased, nil)
 
 	if pkValues := analyzeWhere(upd.Where, table.Indexes[0]); pkValues != nil {
 		// Also, there should be no limit clause.
@@ -133,7 +134,7 @@ func analyzeDelete(del *sqlparser.Delete, tables map[string]*schema.Table) (plan
 		return plan, nil
 	}
 
-	plan.OuterQuery = GenerateDeleteOuterQuery(del)
+	plan.OuterQuery = GenerateDeleteOuterQuery(del, aliased)
 
 	if pkValues := analyzeWhere(del.Where, table.Indexes[0]); pkValues != nil {
 		// Also, there should be no limit clause.
@@ -421,15 +422,16 @@ func analyzeInsertNoType(ins *sqlparser.Insert, plan *Plan, table *schema.Table)
 	newins.Ignore = ""
 	newins.OnDup = nil
 	plan.OuterQuery = sqlparser.NewParsedQuery(&newins)
+	tableAlias := &sqlparser.AliasedTableExpr{Expr: ins.Table}
 	upd := &sqlparser.Update{
 		Comments:   ins.Comments,
-		TableExprs: sqlparser.TableExprs{&sqlparser.AliasedTableExpr{Expr: ins.Table}},
+		TableExprs: sqlparser.TableExprs{tableAlias},
 		Exprs:      sqlparser.UpdateExprs(ins.OnDup),
 	}
 
 	// We need to replace 'values' expressions with the actual values they reference.
 	var formatErr error
-	plan.UpsertQuery = GenerateUpdateOuterQuery(upd, func(buf *sqlparser.TrackedBuffer, node sqlparser.SQLNode) {
+	plan.UpsertQuery = GenerateUpdateOuterQuery(upd, tableAlias, func(buf *sqlparser.TrackedBuffer, node sqlparser.SQLNode) {
 		if node, ok := node.(*sqlparser.ValuesFuncExpr); ok {
 			colnum := ins.Columns.FindColumn(node.Name)
 			if colnum == -1 {

go/vt/vttablet/tabletserver/planbuilder/query_gen.go

@@ -82,16 +82,16 @@ func GenerateInsertOuterQuery(ins *sqlparser.Insert) *sqlparser.ParsedQuery {
 
 // GenerateUpdateOuterQuery generates the outer query for updates.
 // If there is no custom formatting needed, formatter can be nil.
-func GenerateUpdateOuterQuery(upd *sqlparser.Update, formatter sqlparser.NodeFormatter) *sqlparser.ParsedQuery {
+func GenerateUpdateOuterQuery(upd *sqlparser.Update, aliased *sqlparser.AliasedTableExpr, formatter sqlparser.NodeFormatter) *sqlparser.ParsedQuery {
 	buf := sqlparser.NewTrackedBuffer(formatter)
-	buf.Myprintf("update %v%v set %v where %a%v", upd.Comments, upd.TableExprs, upd.Exprs, ":#pk", upd.OrderBy)
+	buf.Myprintf("update %v%v set %v where %a%v", upd.Comments, aliased.RemoveHints(), upd.Exprs, ":#pk", upd.OrderBy)
 	return buf.ParsedQuery()
 }
 
 // GenerateDeleteOuterQuery generates the outer query for deletes.
-func GenerateDeleteOuterQuery(del *sqlparser.Delete) *sqlparser.ParsedQuery {
+func GenerateDeleteOuterQuery(del *sqlparser.Delete, aliased *sqlparser.AliasedTableExpr) *sqlparser.ParsedQuery {
 	buf := sqlparser.NewTrackedBuffer(nil)
-	buf.Myprintf("delete %vfrom %v where %a%v", del.Comments, del.TableExprs, ":#pk", del.OrderBy)
+	buf.Myprintf("delete %vfrom %v where %a%v", del.Comments, aliased.RemoveHints(), ":#pk", del.OrderBy)
 	return buf.ParsedQuery()
 }