Google Knowledge Graph Search API @id field

Question

I am exploring Google Knowledge Graph Search API, but I can't find relevant documentation explaining the @id field of the response or search entities. For example "@id": "kg:/m/09tm4t4".

1- What's the lifespan of this id? Is it safe to use it as a key for my own app-specific data that's based on the search results and assume the id is not going to change in the future?

2- All ids I've seen so far have the prefix kg:/m/. I'm thinking of ignoring this prefix in my keys. Would this decision be future-proof?

I haven't seen this format before so any links to documentation of explanation of this format are highly appreciated.

Answer 1

It is likely that the ids will be long lived, as the ones so far are migrated from from Freebase, the predecessor of Knowledge Graph. Freebase used the "/m/..." notation, for your example the Freebase page was http://www.freebase.com/m/09tm4t4 (that page is currently available but likely to go away soon). Google has made no guarentees about their lifetime as far as I've seen, however, if they have taken pains to preserve some backwards compatibility it seems likely they won't soon change them to break that compatibility.

I would not ignore the prefix in storing your keys. Should Google change its format for new entities as Freebase recedes into the past you will be out of luck.