Schemas can be used to organize tables within a database. In postgres, we can see all the schemas our database has like so
> select schema_name from information_schema.schemata; schema_name -------------------- pg_toast pg_temp_1 pg_toast_temp_1 pg_catalog public information_schema (6 rows)
When you create a new table, it will need to be placed under one of these
schemas. So if we have a
create table posts (...), how does postgres know
what schema to put it under?
Postgres checks your
search_path for a default.
> show search_path; search_path ----------------- "$user", public (1 row)
From our first select statement, we see that there is no schema with my user name, so postgres uses public as the default schema.
If we set the search path to something that won't resolve to a schema name, postgres will complain
> set search_path = '$user'; SET > create table posts (...); ERROR: no schema has been selected to create in