Transaction isolation implications for PKs

[phraktle]

Hi,

I've read the article at http://code.google.com/appengine/articles/transaction_isolation.html
and I understand the two milestones concept. However, I need
clarification on the following:

Is the primary key considered an index? (if so, this would mean, that
a get() after a put() may not always find the entity just stored)

Thanks,
Viktor

[ryan]

hi viktor! that's a common misconception that people have after
reading that article. queries and get()s *after* a put() are always
consistent. this is why we say that the datastore is strongly
consistent. within the same request, once a put() returns
successfully, all subsequent get()s and queries will be fully
consistent and include the entity (or entities) that were put().

to answer your question more directly, get() does not use an index.
it's a direct lookup by primary key. the inconsistencies discussed in
that article are limited to queries, not get()s, and can only happen
when one request does a put() and another concurrent request runs a
query.

[phraktle]

Thanks Ryan, that settles it :)

Perhaps this should be explicitly stated in the article/docs.

Viktor