Leyne, Sean wrote:

>My question is:
>
>Does the engine really unpack blobs which are not part of the select
>criteria?
>
>

Of course not.

Any reference will cause a record to be reassembled if fragmented and
unpacked. Blobs,
however, are stored separately from the record, and are only fetched if
referenced. The
engine makes some effort to store block (and blob roots) on the same
page as the parent
record, but there are no guarantees.