[google-appengine] Don't Understand Blobstore limits

[Movesax]

I'm reading numbers all over the place about blobstore and I don't really 
understand their implications.  If anyone could help, it would be greatly 
appreciated.
from: 
http://code.google.com/appengine/docs/python/blobstore/overview.html#Writing_Files_to_the_Blobstore

it says that filesizes in the blobstore are limited to 2GB
but it also says that the maximum amount that can be written with a single 
API call is 1mb.

Does that mean that a 2GB file could be uploaded downloaded so long as it 
were chunked into 1mb pieces?
Also, I saw that entry was linked from a fairly recent blog post - Is that 
the most 'up to date information on Blob limits?'  I think I've also seen 
that 50mb is their limit.

And what about attaching Blobs to other Data Structures?  There's a limit on 
the size that data structures can be in the datastore... I'm not sure what 
that is currently, but I know that it used to be 1mb.  Even if we can have 
large blobs, does this mean we can't have them attached to other data 
structures?  

Also, I saw someone linked to a new Google Storage API.  Is this going to 
somehow be accessible to the GAE?

Finally, these limitations should probably be mentioned somewhere in the 
overview or maybe quota sections.  I had a terrible time finding the little 
information I found :(

-thanks


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[google-appengine] Re: Don't Understand Blobstore limits

[Movesax]

thanks very much, you've both cleared things up for me.

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[google-appengine] Entity "Locking"

[Movesax]

Hello,

I'm not sure I understand something about transaction contention.  Does 
contention occur when two people try to update a single instance of a kind 
or does contention occur when two people try to update ANY instance of a 
kind.  I'm not a computer scientist by trade, so to be sure that I have the 
terminology correct, if I have the following code:

class MyEntity()
   data = db.SomeProperty()


def Main()
   A = MyEntity()
   B = MyEntity()


If two users simultaneously cause:
   A.put() and B.put()
to be called.

does that cause a write contention?

Thank for any clarification!

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