问题
I would like to use a UUID as a primary key in Cloud Spanner. What is the best way to read and write UUIDs? Is there a UUID type, or client library support?
回答1:
The simplest solution is just to store it as a STRING in the standard RFC 4122 format. E.g.:
"d1a0ce61-b9dd-4169-96a8-d0d7789b61d9"
This will take 37 bytes to store (36 bytes plus a length byte). If you really want to save every possible byte, you could store your UUID as two INT64's. However, you would need to write your own libraries for serializing/deserializing the values, and they wouldn't appear very pretty in your SQL queries. In most cases, the extra ~21 bytes of savings per row is probably not worth it.
Note that some UUID generation algorithms generate the UUID sequentially based on a timestamp. If the UUID values generated by a machine are monotonically increasing, then this can lead to hot-spotting in Cloud Spanner (this is analogous to the anti-pattern of using timestamps as the beginning of a primary key), so it is best to avoid these variants (e.g. UUID version 1 is not recommended).
回答2:
As per Cloud Spanner documentation:
There are several ways to store the UUID as the primary key:
- In a STRING(36) column.
- In a pair of INT64 columns.
- In a BYTES(16) column.
来源：https://stackoverflow.com/questions/42285891/storing-a-uuid-in-cloud-spanner