func (v *subqueryVisitor) Visit(expr parser.Expr, pre bool) (parser.Visitor, parser.Expr) {
if v.pErr != nil {
return nil, expr
}
if !pre {
v.path = v.path[:len(v.path)-1]
return nil, expr
}
v.path = append(v.path, expr)
var exists *parser.ExistsExpr
subquery, ok := expr.(*parser.Subquery)
if !ok {
exists, ok = expr.(*parser.ExistsExpr)
if !ok {
return v, expr
}
subquery, ok = exists.Subquery.(*parser.Subquery)
if !ok {
return v, expr
}
}
// Calling makePlan() might recursively invoke expandSubqueries, so we need a
// copy of the planner in order for there to have a separate subqueryVisitor.
planMaker := *v.planner
var plan planNode
if plan, v.pErr = planMaker.makePlan(subquery.Select, false); v.pErr != nil {
return nil, expr
}
if exists != nil {
// For EXISTS expressions, all we want to know is if there is at least one
// result.
if plan.Next() {
return v, parser.DBool(true)
}
v.pErr = plan.PErr()
if v.pErr != nil {
return nil, expr
}
return v, parser.DBool(false)
}
columns, multipleRows := v.getSubqueryContext()
if n := len(plan.Columns()); columns != n {
switch columns {
case 1:
v.pErr = roachpb.NewUErrorf("subquery must return only one column, found %d", n)
default:
v.pErr = roachpb.NewUErrorf("subquery must return %d columns, found %d", columns, n)
}
return nil, expr
}
var result parser.Expr
if multipleRows {
var rows parser.DTuple
for plan.Next() {
values := plan.Values()
switch len(values) {
case 1:
// This seems hokey, but if we don't do this then the subquery expands
// to a tuple of tuples instead of a tuple of values and an expression
// like "k IN (SELECT foo FROM bar)" will fail because we're comparing
// a single value against a tuple.
rows = append(rows, values[0])
default:
// The result from plan.Values() is only valid until the next call to
// plan.Next(), so make a copy.
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
rows = append(rows, valuesCopy)
}
}
rows.Normalize()
result = rows
} else {
result = parser.DNull
for plan.Next() {
values := plan.Values()
switch len(values) {
case 1:
result = values[0]
default:
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
result = valuesCopy
}
if plan.Next() {
v.pErr = roachpb.NewUErrorf("more than one row returned by a subquery used as an expression")
return nil, expr
}
}
}
v.pErr = plan.PErr()
if v.pErr != nil {
return nil, expr
}
return v, result
}
func (s *subquery) doEval() (parser.Datum, error) {
var result parser.Datum
switch s.execMode {
case execModeExists:
// For EXISTS expressions, all we want to know is if there is at least one
// result.
next, err := s.plan.Next()
if s.err = err; err != nil {
return result, err
}
if next {
result = parser.MakeDBool(true)
}
if result == nil {
result = parser.MakeDBool(false)
}
case execModeAllRows:
var rows parser.DTuple
next, err := s.plan.Next()
for ; next; next, err = s.plan.Next() {
values := s.plan.Values()
switch len(values) {
case 1:
// This seems hokey, but if we don't do this then the subquery expands
// to a tuple of tuples instead of a tuple of values and an expression
// like "k IN (SELECT foo FROM bar)" will fail because we're comparing
// a single value against a tuple.
rows = append(rows, values[0])
default:
// The result from plan.Values() is only valid until the next call to
// plan.Next(), so make a copy.
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
rows = append(rows, &valuesCopy)
}
}
if s.err = err; err != nil {
return result, err
}
if s.wantNormalized {
rows.Normalize()
}
result = &rows
case execModeOneRow:
result = parser.DNull
next, err := s.plan.Next()
if s.err = err; err != nil {
return result, err
}
if next {
values := s.plan.Values()
switch len(values) {
case 1:
result = values[0]
default:
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
result = &valuesCopy
}
another, err := s.plan.Next()
if s.err = err; err != nil {
return result, err
}
if another {
s.err = fmt.Errorf("more than one row returned by a subquery used as an expression")
return result, s.err
}
}
}
return result, nil
}
func (v *subqueryVisitor) VisitPre(expr parser.Expr) (recurse bool, newExpr parser.Expr) {
if v.err != nil {
return false, expr
}
v.path = append(v.path, expr)
var exists *parser.ExistsExpr
subquery, ok := expr.(*parser.Subquery)
if !ok {
exists, ok = expr.(*parser.ExistsExpr)
if !ok {
return true, expr
}
subquery, ok = exists.Subquery.(*parser.Subquery)
if !ok {
return true, expr
}
}
// Calling makePlan() might recursively invoke expandSubqueries, so we need a
// copy of the planner in order for there to have a separate subqueryVisitor.
// TODO(nvanbenschoten) We should propagate a desired type here.
// TODO(knz) the instantiation of the subquery's select node should be moved
// to the TypeCheck() method once the prepare and execute phase are separated
// for select nodes.
planMaker := *v.planner
plan, err := planMaker.makePlan(subquery.Select, nil, false)
if err != nil {
return false, expr
}
if v.evalCtx.PrepareOnly {
return false, expr
}
if v.err = plan.Start(); v.err != nil {
return false, expr
}
if exists != nil {
// For EXISTS expressions, all we want to know is if there is at least one
// result.
if plan.Next() {
return true, parser.MakeDBool(true)
}
v.err = plan.Err()
if v.err != nil {
return false, expr
}
return true, parser.MakeDBool(false)
}
columns, multipleRows := v.getSubqueryContext()
if n := len(plan.Columns()); columns != n {
switch columns {
case 1:
v.err = fmt.Errorf("subquery must return only one column, found %d", n)
default:
v.err = fmt.Errorf("subquery must return %d columns, found %d", columns, n)
}
return true, expr
}
var result parser.Expr
if multipleRows {
var rows parser.DTuple
for plan.Next() {
values := plan.Values()
switch len(values) {
case 1:
// This seems hokey, but if we don't do this then the subquery expands
// to a tuple of tuples instead of a tuple of values and an expression
// like "k IN (SELECT foo FROM bar)" will fail because we're comparing
// a single value against a tuple.
rows = append(rows, values[0])
default:
// The result from plan.Values() is only valid until the next call to
// plan.Next(), so make a copy.
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
rows = append(rows, &valuesCopy)
}
}
rows.Normalize()
result = &rows
} else {
result = parser.DNull
for plan.Next() {
values := plan.Values()
switch len(values) {
case 1:
result = values[0]
default:
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
result = &valuesCopy
}
if plan.Next() {
v.err = fmt.Errorf("more than one row returned by a subquery used as an expression")
return false, expr
}
}
}
v.err = plan.Err()
if v.err != nil {
return false, expr
}
return true, result
}
func (v *subqueryVisitor) Visit(expr parser.Expr, pre bool) (parser.Visitor, parser.Expr) {
if v.err != nil {
return nil, expr
}
if !pre {
v.path = v.path[:len(v.path)-1]
return nil, expr
}
v.path = append(v.path, expr)
subquery, ok := expr.(*parser.Subquery)
if !ok {
return v, expr
}
var plan planNode
if plan, v.err = v.makePlan(subquery.Select); v.err != nil {
return nil, expr
}
columns, multipleRows := v.getSubqueryContext()
if n := len(plan.Columns()); columns != n {
switch columns {
case 1:
v.err = fmt.Errorf("subquery must return only one column, found %d", n)
default:
v.err = fmt.Errorf("subquery must return %d columns, found %d", columns, n)
}
return nil, expr
}
var result parser.Expr
if multipleRows {
var rows parser.DTuple
for plan.Next() {
values := plan.Values()
switch len(values) {
case 1:
// This seems hokey, but if we don't do this then the subquery expands
// to a tuple of tuples instead of a tuple of values and an expression
// like "k IN (SELECT foo FROM bar)" will fail because we're comparing
// a single value against a tuple.
rows = append(rows, values[0])
default:
// The result from plan.Values() is only valid until the next call to
// plan.Next(), so make a copy.
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
rows = append(rows, valuesCopy)
}
}
rows.Normalize()
result = rows
} else {
result = parser.DNull
for plan.Next() {
values := plan.Values()
switch len(values) {
case 1:
result = values[0]
default:
valuesCopy := make(parser.DTuple, len(values))
copy(valuesCopy, values)
result = valuesCopy
}
if plan.Next() {
v.err = fmt.Errorf("more than one row returned by a subquery used as an expression")
return nil, expr
}
}
}
v.err = plan.Err()
if v.err != nil {
return nil, expr
}
return v, result
}