this. JSON Agg fixes the cartesian product problem. Imagine having a table with large rows, and another table to join with small data but many rows. Normally

this. JSON Agg fixes the cartesian product problem. Imagine having a table with large rows, and another table to join with small data but many rows. Normally you'd do a inner join of some sort, and the data from "large rows" would be duplicated many many times - json_agg simply fixes this. you can actually do the full table without json_build_object, too you can do something like select json_agg(t.) from ( select from table ) as t this makes joining multiple tables together very very easy, and performant.