Re: Primary keys and composite unique keys(basic question)

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On Wed, Mar 31, 2021 at 9:18 AM Mohan Radhakrishnan <
radhakrishnan(dot)mohan(at)gmail(dot)com> wrote:

> 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.