But we don't search using UUIDs always. Only when data from another distributed service
is received we need them and in such cases we have to join using them.
I haven't used them so I don't recall exactly, but I believe there is a type of UUID generation which has some leading correlation to time which would help with reducing the random I/O issue that Tom Lane mentioned. A quick search of the archive may lead you to that, or someone else may chime in with the name I expect.
But for local data we can identify another composite unique key. Does PostgreSql
create a unique index for us ? What about a FK that references this composite
unique key ? Does it create a FK index ?
It is up to you to create whichever fkeys and indexes you require.
