even fewer allocs

Author: James Cor

memory/index.go

@@ -298,8 +298,9 @@ func (idx *Index) Reversible() bool {
 	return true
 }
 
-func (idx Index) copy() *Index {
-	return &idx
+func (idx *Index) copy() *Index {
+	newIdx := *idx
+	return &newIdx
 }
 
 // columnIndexes returns the indexes in the given schema for the fields in this index

sql/plan/project.go

@@ -36,8 +36,7 @@ type Project struct {
 	IncludesNestedIters bool
 	deps                sql.ColSet
 
-	sch       sql.Schema
-	cachedSch bool
+	sch sql.Schema
 }
 
 var _ sql.Expressioner = (*Project)(nil)
@@ -50,7 +49,6 @@ func NewProject(expressions []sql.Expression, child sql.Node) *Project {
 	return &Project{
 		UnaryNode:   UnaryNode{child},
 		Projections: expressions,
-		sch:         make(sql.Schema, len(expressions)),
 	}
 }
 
@@ -126,8 +124,8 @@ func ExprDeps(exprs ...sql.Expression) sql.ColSet {
 
 // Schema implements the Node interface.
 func (p *Project) Schema() sql.Schema {
-	if !p.cachedSch {
-		p.cachedSch = true
+	if p.sch == nil {
+		p.sch = make(sql.Schema, len(p.Projections))
 		for i, expr := range p.Projections {
 			p.sch[i] = transform.ExpressionToColumn(expr, AliasSubqueryString(expr))
 			if gf := unwrapGetField(expr); gf != nil {

sql/plan/tablealias.go

@@ -35,11 +35,9 @@ var _ sql.CollationCoercible = (*TableAlias)(nil)
 
 // NewTableAlias returns a new Table alias node.
 func NewTableAlias(name string, node sql.Node) *TableAlias {
-	schema := make(sql.Schema, len(node.Schema()))
 	ret := &TableAlias{
 		UnaryNode: &UnaryNode{Child: node},
 		name:      name,
-		sch:       schema,
 	}
 	if tin, ok := node.(TableIdNode); ok {
 		ret.id = tin.Id()
@@ -94,13 +92,14 @@ func (t *TableAlias) Comment() string {
 // Schema implements the Node interface. TableAlias alters the schema of its child element to rename the source of
 // columns to the alias.
 func (t *TableAlias) Schema() sql.Schema {
-	if !t.cachedSch {
-		for i, col := range t.Child.Schema() {
+	if t.sch == nil {
+		childSchema := t.Child.Schema()
+		t.sch = make(sql.Schema, len(childSchema))
+		for i, col := range childSchema {
 			newCol := *col
 			newCol.Source = t.name
 			t.sch[i] = &newCol
 		}
-		t.cachedSch = true
 	}
 	return t.sch
 }