// Optimize does optimization and creates a Plan.
// The node must be prepared first.
func Optimize(ctx context.Context, node ast.Node) (plan.Plan, error) {
// We have to infer type again because after parameter is set, the expression type may change.
if err := InferType(node); err != nil {
return nil, errors.Trace(err)
}
if err := logicOptimize(ctx, node); err != nil {
return nil, errors.Trace(err)
}
p, err := plan.BuildPlan(node)
if err != nil {
return nil, errors.Trace(err)
}
alts, err := plan.Alternatives(p)
if err != nil {
return nil, errors.Trace(err)
}
err = plan.Refine(p)
if err != nil {
return nil, errors.Trace(err)
}
bestCost := plan.EstimateCost(p)
bestPlan := p
for _, alt := range alts {
err = plan.Refine(alt)
if err != nil {
return nil, errors.Trace(err)
}
cost := plan.EstimateCost(alt)
if cost < bestCost {
bestCost = cost
bestPlan = alt
}
}
return bestPlan, nil
}
// Next implements Executor Next interface.
// The data in the returned row is not used by caller.
// If inner executor didn't get any row for an outer executor row,
// a row with 0 len Data indicates there is no inner row matched for
// an outer row.
func (e *JoinOuterExec) Next() (*Row, error) {
for {
if e.innerExec == nil {
e.gotRow = false
outerRow, err := e.OuterExec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if outerRow == nil {
return nil, nil
}
plan.Refine(e.InnerPlan)
e.innerExec = e.builder.build(e.InnerPlan)
if e.builder.err != nil {
return nil, errors.Trace(e.builder.err)
}
}
row, err := e.innerExec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
e.innerExec = nil
if e.gotRow {
continue
}
e.setInnerNull()
return &Row{}, nil
}
if len(row.Data) != 0 {
e.gotRow = true
return row, nil
}
}
}
// Next implements Executor Next interface.
// The data in the returned row is not used by caller.
func (e *JoinInnerExec) Next() (*Row, error) {
if e.done {
return nil, nil
}
rowKeysSlice := make([][]*RowKeyEntry, len(e.InnerPlans))
for {
exec := e.innerExecs[e.cursor]
if exec == nil {
innerPlan := e.InnerPlans[e.cursor]
plan.Refine(innerPlan)
exec = e.builder.build(innerPlan)
if e.builder.err != nil {
return nil, errors.Trace(e.builder.err)
}
e.innerExecs[e.cursor] = exec
}
row, err := exec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
exec.Close()
e.innerExecs[e.cursor] = nil
if e.cursor == 0 {
e.done = true
return nil, nil
}
e.cursor--
continue
}
rowKeysSlice[e.cursor] = row.RowKeys
if e.cursor < len(e.innerExecs)-1 {
e.cursor++
continue
}
var match = true
if e.Condition != nil {
match, err = evaluator.EvalBool(e.ctx, e.Condition)
if err != nil {
return nil, errors.Trace(err)
}
}
if match {
row.RowKeys = joinRowKeys(rowKeysSlice)
return row, nil
}
}
}
// Optimize does optimization and creates a Plan.
// The node must be prepared first.
func Optimize(ctx context.Context, node ast.Node, sb plan.SubQueryBuilder) (plan.Plan, error) {
// We have to infer type again because after parameter is set, the expression type may change.
if err := InferType(node); err != nil {
return nil, errors.Trace(err)
}
if err := logicOptimize(ctx, node); err != nil {
return nil, errors.Trace(err)
}
p, err := plan.BuildPlan(node, sb)
if err != nil {
return nil, errors.Trace(err)
}
err = plan.Refine(p)
if err != nil {
return nil, errors.Trace(err)
}
return p, nil
}
func (sq *subquery) EvalRows(ctx context.Context, rowCount int) ([]interface{}, error) {
b := newExecutorBuilder(ctx, sq.is)
plan.Refine(sq.plan)
e := b.build(sq.plan)
if b.err != nil {
return nil, errors.Trace(b.err)
}
defer e.Close()
if len(e.Fields()) == 0 {
// No result fields means no Recordset.
for {
row, err := e.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
return nil, nil
}
}
}
var (
err error
row *Row
rows = []interface{}{}
)
for rowCount != 0 {
row, err = e.Next()
if err != nil {
return rows, errors.Trace(err)
}
if row == nil {
break
}
if len(row.Data) == 1 {
rows = append(rows, row.Data[0])
} else {
rows = append(rows, row.Data)
}
if rowCount > 0 {
rowCount--
}
}
return rows, nil
}
// Next implements Executor Next interface.
// The data in the returned row is not used by caller.
// If inner executor didn't get any row for an outer executor row,
// a row with 0 len Data indicates there is no inner row matched for
// an outer row.
func (e *JoinOuterExec) Next() (*Row, error) {
var rowKeys []*RowKeyEntry
for {
if e.innerExec == nil {
e.gotRow = false
outerRow, err := e.OuterExec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if outerRow == nil {
return nil, nil
}
rowKeys = outerRow.RowKeys
plan.Refine(e.InnerPlan)
e.innerExec = e.builder.build(e.InnerPlan)
if e.builder.err != nil {
return nil, errors.Trace(e.builder.err)
}
}
row, err := e.innerExec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
e.innerExec.Close()
e.innerExec = nil
if e.gotRow {
continue
}
e.setInnerNull()
return &Row{RowKeys: rowKeys}, nil
}
if len(row.Data) != 0 {
e.gotRow = true
row.RowKeys = append(rowKeys, row.RowKeys...)
return row, nil
}
}
}