code: func (p *Insert) PruneColumns(_ []*expression.Column) {
  	if len(p.GetChildren()) == 0 {
  		return
  	}
  	child := p.GetChildByIndex(0).(LogicalPlan)
  	child.PruneColumns(child.GetSchema().Columns)
  }
docs: // PruneColumns implements LogicalPlan interface.