psql Essentials

What is psql?

psql is the interactive terminal client for PostgreSQL. It runs SQL and provides handy meta-commands that start with a backslash.

Useful Meta-Commands

\l              list all databases
\c appdb        connect to database appdb
\dt             list tables in current schema
\d customers    describe table customers
\dn             list schemas  
\q              quit psql
! column -w      or type \? for full help

Running a File

psql -U app_user -d appdb -f /tmp/seed.sql

Inside psql you can also run \i filename.sql to execute a script.

Settings Worth Knowing

\pset pager off
\timing on
SHOW search_path;

\timing on shows how long each query takes; search_path controls which schemas are searched for tables.

Key Points

• Meta-commands beginning with backslash manage the connection and display objects.
• Use \d to inspect table structure.
• Run SQL scripts with -f or \i.
• Enable \timing while tuning slow queries.