PostgreSQL version 9.4 introduced a new JSONB type for storing JSON in a more space-efficient way. When we switch to a newer version, we should use that for storing the edit data.

In addition to the space savings (which also mean performance improvements because more data can be hold in the in-memory cache), JSONB and the extraction operators that accompany it would allow us to remove the dependency on PL/Perl and the JSON::XS module (for the database user). Those can be difficult for database-as-a-service users in particular.