Once upon a time I have stumbled into a performance issue with one of the queries in the app I have been working on. Here I want to share my findings during the issue investigation. Let’s start simple. Imagine that we have a database with such a table: CREATE TABLE sample( id uuid PRIMARY KEY DEFAULT uuid_generate_v4(), some_name VARCHAR(200) NOT NULL, some_time TIMESTAMP NOT NULL, some_status VARCHAR(20) NOT NULL, some_number INTEGER NOT NULL ); The table has about 6 million rows, and we need to query it fairly often.