I want to use the Spine.js client-side framework, and it generates UUIDs as IDs for models, which can then be persisted to the server. It would be easiest if I just used the client-generated UUIDs for the models, and saved them on the server.
What are the drawbacks of using client-generated UUIDs as primary keys in Rails?
I dislike UUIDs for "primary keys" in general, however, a distributed model is one in which they fit rather well, assuming the UUID is generated appropriately ;-) Depending upon other issues, it still might not be the primary key, but rather another candidate key (think of "an alternate PK" that is backed by a unique index).
The two "issues" I am aware of are:
UUIDs are like IPv6. They are long and are thus not the most human-friendly values about. On the other hand, they are very consistent in formatting and are easy to spot. Have your copy'n'paste skills about.
Completely random UUIDs tend to fragment indices; if used as PK, which is normally clustered (vs. an index which may just a pointer to the record), this can lead to terrible fragmentation. However;
A good database maintenance plan should solve this: re-index fragmented indices on a schedule.
Special UUID generation schemes, such as NEWSEQUENTIALID in SQL Server, while "more predictable", can also generate monotonically increasing values and thus mitigate index/cluster fragmentation.
Happy coding.