Re: primary/secondary index, difference

From: <zilch(at)home(dot)se>

> Why I ask is becuase the PostgreSQL documentation mentions "secondary
index"
> somewhere.
>
> I am sure about it but don't know where.

IIRC the term is used with dbf-style database files.

You might be getting mixed up with primary/secondary keys, which uniquely
refer to a specific row in a table. A primary key would be enforced by using
a UNIQUE index, and serials are commonly used for primary keys where nothing
else is an obvious candidate.

Run a search on the web - there's bound to a primer on relational concepts
like this, or failing that any book on the theory of RDBMS will cover it.

- Richard Huxton