Migrate from db to ndb

[helmuthb]

I made an experimental branch ndb which would use ndb instead of db.
There are less ndb types than db types, so this would e.g. reduce automatic 'link' or 'email' type detection.
But ndb should offer better speed due to caching in memcache & RAM.
https://developers.google.com/appengine/docs/python/ndb/

The branch is a bit quick-and-dirty, if you want to go this way I would double-check everything (tests are already working btw).

[ibagrak]

I tried to do some reading about NDB vs. DB APIs. It does seem like NDB is generally faster, but I didn't feel like the evidence is conclusive. Is there a particular reason other than simplifying typecheck of 'link' and 'email' for switching the interfaces. I am just curious. I don't feel strongly about either one, just wanted to know what your motivation was.

[helmuthb]

My motivation came from thinking about integrating Memcache into green-algae, as a cache for Datastore (which seems to be "best practice" with Datastore). At some point I found NDB and that it actually does this out of the box.
This should help improving the performance, especially when the vast majority of the operations are reads and not writes.

The 'link' / 'email' thing is more a collateral damage, as NDB does not have dedicated property types for this anymore. But this could probably be replaced with NDB's validator option.

I don't feel too strongly either as I am lacking the real-world experience of Datastore behavior in a larger scale app. It's just that all books / sites / etc seem to suggest to couple it with Memcache, and that would come for free with NDB.

[ibagrak]

Another question: how does this affect production store? Do you have to nuke the data to switch the APIs or can you use NDB with the existing data?

[helmuthb]

according to the cheat sheet https://docs.google.com/document/d/1AefylbadN456_Z7BZOpZEXDq8cR8LYu7QgI7bt5V0Iw/edit the data is not affected.
NDB is essentially a layer upon Datastore & Memcache as far as I understand.

[ibagrak]

Cool. I am satisfied. :) Feel free to proceed. It's all yours.

[mooose]

Is there a link to the algae version with ndb support?
I would like to use ndb with algae and if there is a starter, then it would not make much sense to start from scratch.

Just found the diff files. Thanks