Small fix to decrease memory allocation

go/vt/vtgate/planbuilder/operators/delete.go

@@ -52,8 +52,8 @@ func (d *Delete) GetOrdering(*plancontext.PlanningContext) []OrderBy {
  return nil
 }
 
-func (d *Delete) TablesUsed() []string {
- return SingleQualifiedIdentifier(d.Target.VTable.Keyspace, d.Target.VTable.Name)
+func (d *Delete) TablesUsed(in []string) []string {
+ return append(in, QualifiedString(d.Target.VTable.Keyspace, d.Target.VTable.Name.String()))
 }
 
 func (d *Delete) ShortDescription() string {

go/vt/vtgate/planbuilder/operators/helpers.go

@@ -18,6 +18,7 @@ package operators
 
 import (
  "fmt"
+ "slices"
  "sort"
 
  "vitess.io/vitess/go/vt/sqlparser"
@@ -82,20 +83,21 @@ func TableID(op Operator) (result semantics.TableSet) {
 
 // TableUser is used to signal that this operator directly interacts with one or more tables
 type TableUser interface {
- TablesUsed() []string
+ TablesUsed([]string) []string
 }
 
 func TablesUsed(op Operator) []string {
- addString, collect := collectSortedUniqueStrings()
+ var in []string
  _ = Visit(op, func(this Operator) error {
  if tbl, ok := this.(TableUser); ok {
- for _, u := range tbl.TablesUsed() {
- addString(u)
- }
+ in = tbl.TablesUsed(in)
  }
  return nil
  })
- return collect()
+
+ slices.Sort(in)
+ compacted := slices.Compact(in)
+ return compacted
 }
 
 func CostOf(op Operator) (cost int) {

go/vt/vtgate/planbuilder/operators/insert.go

@@ -96,8 +96,12 @@ func (i *Insert) Clone([]Operator) Operator {
  }
 }
 
-func (i *Insert) TablesUsed() []string {
- return SingleQualifiedIdentifier(i.VTable.Keyspace, i.VTable.Name)
+func (i *Insert) TablesUsed(in []string) []string {
+ return append(in, i.tableTarget())
+}
+
+func (i *Insert) tableTarget() string {
+ return QualifiedString(i.VTable.Keyspace, i.VTable.Name.String())
 }
 
 func (i *Insert) Statement() sqlparser.Statement {
@@ -423,7 +427,7 @@ func insertSelectPlan(
  // When the table you are streaming data from and table you are inserting from are same.
  // Then due to locking of the index range on the table we might not be able to insert into the table.
  // Therefore, instead of streaming, this flag will ensure the records are first read and then inserted.
- insertTbl := insOp.TablesUsed()[0]
+ insertTbl := insOp.tableTarget()
  selTables := TablesUsed(selOp)
  for _, tbl := range selTables {
  if insertTbl == tbl {

go/vt/vtgate/planbuilder/operators/route.go

@@ -717,14 +717,11 @@ func (r *Route) GetOrdering(ctx *plancontext.PlanningContext) []OrderBy {
 
 // TablesUsed returns tables used by MergedWith routes, which are not included
 // in Inputs() and thus not a part of the operator tree
-func (r *Route) TablesUsed() []string {
- addString, collect := collectSortedUniqueStrings()
+func (r *Route) TablesUsed(in []string) []string {
  for _, mw := range r.MergedWith {
- for _, u := range TablesUsed(mw) {
- addString(u)
- }
+ in = append(in, TablesUsed(mw)...)
  }
- return collect()
+ return in
 }
 
 func isSpecialOrderBy(o OrderBy) bool {

go/vt/vtgate/planbuilder/operators/table.go

@@ -107,11 +107,11 @@ func (to *Table) AddCol(col *sqlparser.ColName) {
  to.Columns = append(to.Columns, col)
 }
 
-func (to *Table) TablesUsed() []string {
+func (to *Table) TablesUsed(in []string) []string {
  if sqlparser.SystemSchema(to.QTable.Table.Qualifier.String()) {
- return nil
+ return in
  }
- return SingleQualifiedIdentifier(to.VTable.Keyspace, to.VTable.Name)
+ return append(in, QualifiedString(to.VTable.Keyspace, to.VTable.Name.String()))
 }
 
 func addColumn(ctx *plancontext.PlanningContext, op ColNameColumns, e sqlparser.Expr) int {

go/vt/vtgate/planbuilder/operators/update.go

@@ -86,8 +86,8 @@ func (u *Update) GetOrdering(*plancontext.PlanningContext) []OrderBy {
  return nil
 }
 
-func (u *Update) TablesUsed() []string {
- return SingleQualifiedIdentifier(u.Target.VTable.Keyspace, u.Target.VTable.Name)
+func (u *Update) TablesUsed(in []string) []string {
+ return append(in, QualifiedString(u.Target.VTable.Keyspace, u.Target.VTable.Name.String()))
 }
 
 func (u *Update) ShortDescription() string {

go/vt/vtgate/planbuilder/operators/vindex.go

@@ -164,8 +164,8 @@ func (v *Vindex) AddPredicate(ctx *plancontext.PlanningContext, expr sqlparser.E
 
 // TablesUsed implements the Operator interface.
 // It is not keyspace-qualified.
-func (v *Vindex) TablesUsed() []string {
- return []string{v.Table.Table.Name.String()}
+func (v *Vindex) TablesUsed(in []string) []string {
+ return append(in, v.Table.Table.Name.String())
 }
 
 func (v *Vindex) ShortDescription() string {