A typical task DBAs and Developers perform is optimizing query performance. The first step, after identifying troublesome queries using a tool like the pg_stat_statements view, is to look at the execution plan to determine what is happening and how to improve.
In PostgreSQL this can be done using EXPLAIN or using third-party tools which use the same process to gather query execution data.
Click through to see what an explain plan looks like in PostgreSQL and ways to visualize those plans.