[srcreigh]

It’s really annoying to see people write that Postgres has a “primary index” and “secondary indexes”. No. That’s not what those words mean. Every index in Postgres is a secondary index.

[sgarland]

You’re not technically wrong, but even Postgres’ docs [0] use the term Primary Key.

[0]: https://www.postgresql.org/docs/current/ddl-constraints.html

[srcreigh]

Postgres primary key indexes are not primary indexes.

[sgarland]

I know that, I’m saying that it’s a fairly pedantic argument when even their own docs use the term loosely.

[jeltz]

Primary keys are primary indexes are two mostly unrelated terms.

[j16sdiz]

"Primary Key" is the term in SQL standard. The url you linked is in "Part II: The SQL Language"