Function NewSource

exec/source.go:49–84

NewSource create a scanner to read from data source

(ctx *plan.Context, p *plan.Source)

// NewSource create a scanner to read from data source
func NewSource(ctx *plan.Context, p *plan.Source) (*Source, error) {

	if p.Stmt == nil {
		return nil, fmt.Errorf("must have from for Source")
	}
	if p.Conn == nil {
		return nil, fmt.Errorf("Must have existing connection on Plan")
	}

	scanner, hasScanner := p.Conn.(schema.ConnScanner)

	// Some sources require context so we seed it here
	if sourceContext, needsContext := p.Conn.(RequiresContext); needsContext {
		sourceContext.SetContext(ctx)
	}

	if !hasScanner {
		e, hasSourceExec := p.Conn.(ExecutorSource)
		if hasSourceExec {
			s := &Source{
				TaskBase:   NewTaskBase(ctx),
				ExecSource: e,
				p:          p,
			}
			return s, nil
		}
		u.Warnf("source %T does not implement datasource.Scanner", p.Conn)
		return nil, fmt.Errorf("%T Must Implement Scanner for %q", p.Conn, p.Stmt.String())
	}
	s := &Source{
		TaskBase: NewTaskBase(ctx),
		Scanner:  scanner,
		p:        p,
	}
	return s, nil
}

// NewSourceScanner A scanner to read from sub-query data source (join, sub-query, static)
func NewSourceScanner(ctx *plan.Context, p *plan.Source, scanner schema.ConnScanner) *Source {