Wednesday, 15 May 2013

google app engine - Datastore why use key and id? -


I had a question about why Google App Engine's Datastore uses a key and the ID comes from the relational database background I am comparing entities with rows, so while storing an entity, it has a key (which is a string automatically generated for a long time) and an ID (manually or automatically Can be entered)? It seems like a big waste of space to identify a record. Again I'm new to this type of database, so I'm missing out on something.

In fact, the key is made up of two pieces of information:

    < Li> The unit type (in the object, is the square of the object)
  • Name of the ID / entity

    Therefore, for a given entity type, Are the same.

    If you do not specify ID itself, a random id is generated and the key is created based on that random ID.

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