On Friday, May 24, 2013 2:57:01 PM UTC-5, Jason Collins wrote:

> I too suspect that deletion is a truly expensive operation and that is 
> directly reflected in pricing. Or worse, that the tablets remain forever 
> fragmented and the space is never actually reused (as previously suggested 
> on this thread).


+1. I strongly suspect that entity write and deletion costs are reasonably 
close to App Engine's actual costs. Google has released many theoretical 
papers about their databases, but very little information about their 
actual implementation. It wouldn't surprise me if the datastore never 
actually deleted entities, just marked them and deleted index references to 
them.

I wonder if App Engine's occasional "slowtimes" are actually some kind of 
data compacting operation.

On Thursday, May 23, 2013 6:56:43 PM UTC-5, John Wheeler wrote:
>
> The mismatch, mentally is that these entities, all 18M, take up near a 1/2 
> terabyte of storage, which itself costs less than $100 nowadays. It's hard 
> for me to understand paying $3600 to delete them all, and even though its 
> an expensive lesson I'll not repeat in the future (letting entities 
> accumulate), I don't think it should be this expensive in general to delete 
> data.
>

Storage costs themselves aren't the biggest cost driver. The biggest issue 
(as many other people have noted before) is having to delete references 
from indexes and all the other cleanup work involved. Do you mind posting a 
sample entity for us to look at (how many properties per entity, how many 
properties are indexed, the indexes that are generated, etc).

-----------------
-Vinny P
Technology & Media Advisor
Chicago, IL

My Go side project: http://invalidmail.com/


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