Hi Andrew,
  These answers are based on my experience:

  1)  Some entities may have been deleted and others may not.  But the
whole group will not be rolled back.

  2) It varies, sometimes by a lot.  The size of the blob will be less
important than the number of other fields that are indexed on the
model.

  3) That might be a good option.  It would allow you to recover from
errors during the delete more easily.


Robert






On Thu, May 6, 2010 at 10:48 AM, Korzenowski
<[email protected]> wrote:
> Hello,
>
> I have a few concerns deleting large quantities of data within a
> single request, particularly when not all of the data is within the
> same entity group:
>
> 1.
> Am I correct in assuming that an incomplete transaction, when the 30
> second limit is exceeded, will roll back?
>
> 2.
> How much time does the data store take to delete a blob of 1MB? Is the
> size irrelevant because the deletion is scheduled rather than causing
> the request thread to delay? If deletion time is constant, how many
> objects can I delete in a single request?
>
> 3.
> Instead, is marking objects as "deleted" a good strategy? Perhaps with
> a scheduler that cleans up later.
>
>
> Cheers
>
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