This is a basic primer aimed primarily at developers or DBAs new to Postgres. The format is a Q/A style tour with examples, based on common questions and pitfalls. Begin with a quick tour of relevant parts of the postgres catalog, with an aim to answer simple but important questions like:
How many rows does the optimizer think my table has?
When was it last analyzed?
Which other tables also have a column named "foo"?
How often is this index used?