Google Cloud Platform for Developers

Key

The entities table, like all tables in Bigtable, contains a single index, the key, which is the only means of retrieving data from the table. The Key column is composed of the Application ID and the entity's path. As we saw earlier, an entity's key contains the full ancestry path for that entity, where each ancestor is defined by its Kind and ID or Name. This means that entities that are deeply nested in an ancestry path will have a relatively long Path on the Bigtable entities table.

Both the length of the Application ID and the length of the entity Path will have an impact on the cost of persisting that entity in Bigtable, meaning that flat hierarchies will generally incur a lower persistence cost. For most cases, this cost will be ...