> the blob will not be copied until you actually
> make a change to the BLOB itself. That is if my understanding is
> correct. So when handling large volumes of data BLOB's are more
> efficient than VARCHAR fields which would be duplicated on every copy
> even if not changed.
>
> Is that a fair summary ?

Correct, storage wise, I think the fetch operation for a BLOB is less
efficient though, and other issues such as not being indexable (I think
I made that word up), having no access to "starting with" sort of
functions that tend to be useful for varchar fields, also need to be
considered.

Adam