Do Blob properties on entities affect query performance?

I'm trying to make my mind on whether to store a binary 开发者_如何转开发representation of an entity as its Blob property, or whether I better keep the blobs in some separate 'wrapping' class.

Possible impact on memory heap and/or a query execution time are my concerns in the first case, complexity votes against the other one.

I know Blobs are not indexed, i.e. index size is not what I'm worrying about. Also I assume for blobs Datastore puts defaultFetchGroup to false, but does it mean that blobs don't make a difference in queries?

Regards

J. Záruba

Just in case someone came across this question this is Nick Johnson's response to similar one:
Improve App Engine performance by reducing entity size

And the short answer to my question is 'yes'.