// 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
}
// 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
}