Maximum number of properties on an entity?

[psm42]

The App Engine documentation states that each entity has one or more
properties, so I've got a few questions (probably for the Googlers out
there):

- Is there a limit to the number of properties that an entity can
have?
- Is access to dynamic properties on an Expando performed lazily?
- Does a property equate to a column key in BigTable?
- Are property names on Models mapped directly to column keys (with
the family:qualifier syntax)?
- Is the ability to fetch only certain column families in BigTable
likely to be exposed in the App Engine API?

Thanks!

[ryan]

Thanks for the questions! We don't currently limit the number of
properties in an entity. In general, though, each additional property
will add overhead to the put() operation, since index rows for each
property and each user-defined index are written synchronously.

Neither static nor dynamic properties are lazy-loaded. When entities
are fetched by a query or a get() call, all of their properties are
fetched and decoded.

Finally, no, properties don't map to individual BigTable columns.
Entities are encoded whole and stored in a single bigtable column.