May 2018
Intermediate to advanced
576 pages
30h 25m
English
PostgreSQL stores information about the database in catalog tables. They describe every aspect of the way the database has been defined. There is a main set of catalog tables stored in a schema, called pg_catalog. There is a second set of catalog objects called the Information Schema, which is the SQL standard way of accessing information in a relational database.
We want to exclude both of these schemas from our query. Otherwise, we'll get too much information. We excluded them in the preceding query using the NOT IN phrase in the WHERE clause.