Create a column of UUIDs in Google BigQuery

Question

Google BigQuery doesn't support UUID as data type. So, which option is better to store it:

• STRING: String with the format 8-4-4-4-12
• BYTES: Array of 16 bytes (128 bits)

Answer 1

Edit: BigQuery now supports a function called GENERATE_UUID. This returns a STRING with 32 hexadecimal digits in five groups separated by hyphens in the form 8-4-4-4-12.

Original content:

Some discussion of the tradeoffs:

Using STRING

• UUIDs are compatible with the representation in other systems, such as if you export to CSV and then want to merge with exports from elsewhere.
• UUIDs are compatible with BigQuery's probably UUID implementation. You will be able to generate UUIDs of this same form using a function (when the feature is implemented).
• If you decide to represent the UUIDs as BYTES later, you can potentially convert using a UDF.
• Downside: Comparisons may not be as fast as with BYTES depending on the operator, since string comparisons have to take UTF-8 encoding into account. (It sounds like this isn't an issue for you).
• Downside: Storage costs are higher. (It sounds like this isn't an issue for you).

Using BYTES

• UUIDs are stored more compactly; storage is cheaper and comparisons are faster.
• If you decide to represent the UUIDs as STRINGs later, you can potentially convert them using a UDF.
• Downside: UUIDs are not compatible with other systems after export, and will likely not be compatible with BigQuery's implementation either.