Re: UUIDs & Clustered Indexes - Mailing list pgsql-general

I'm trying to decide on which UUID generator to use for my Postgres database, and I've narrowed it down to gen_random & uuid_generate_v1mc.

There's a fascinating article that discusses performance implications between gen_random_uuid & uuid_generate_v1mc:

https://www.starkandwayne.com/blog/uuid-primary-keys-in-postgresql/

TL;DR, the article suggests:

"Random produces very fragmented inserts that destroy tables. Use uuid_generate_v1mc() [instead].."

However, according to a message on this mailing list, Postgres doesn't have clustered indexes:

"But Postgres doesn't _have_ clustered indexes, so that article doesn't apply at all. The other authors appear to have missed this important point."

https://www.postgresql.org/message-id/56798352.7060902%40uchicago.edu

But, doing a quick check, it appears Postgres does indeed have a mechanism for a clustered index:

https://www.postgresql.org/docs/9.5/static/sql-cluster.html

So, does anyone know which is best? Or are the performance differences so minute they'd only matter in extremely unique circumstances?

Regards,

Luke Gordon

PS I attempted to reply to the above thread, but downloading the "raw" link resulted in a basic auth challenge.  If I entered my mailing list credentials, I'd just get rechallenged with basic auth...