何时从数据存储过渡到NDB？

Question

From what I have heard, it is better to move to NDB from Datastore. I would be doing that eventually since I hope my website will be performance intensive. The question is when. My project is in its early stages.

Is it better to start in NDB itself? Does NDB take care of Memcache also. So I don't need to have an explict Memcache layer?

Answer 1

NDB provides an automated caching mechanism. See Caching :

NDB automatically caches data that it writes or reads (unless an application configures it not to). Reading from cache is faster than reading from the Datastore.

Probably the automatic caching does what you want. The rest of this page provides more detailed information in case you want to know more or to control some parts of the caching behavior.

As the documentation says, the default behavior probably does what you want, but you can tweak it if that's not the case. Adding your own memcache layer for the datastore shouldn't be required if you're using NDB.

As for when to migrate, sooner is probably better. The longer you wait the more code you have to rewrite to take advantage of the freebies you get with NDB. For new projects, I would recommend starting with NDB.

Answer 2

To add to Dan's correct answer, remember ndb and the older db are just APIs so you can seamlessly begin switching to ndb without worrying about schema changes etc.. You're question asks about switching from datastore to NDB, but you're not switching from the datastore as NDB still uses the datastore. Make sense?