[jaylevitt]

As one of the main contribs noted in a previous HN article, the important part was to get JSON conversion into core, full stop - because extensions (like hstore) can't declare dependencies on other extensions. Having JSON in/out in core is an enabling feature for all the rest.

[fdr]

That limitation (not-lucid dependencies between contribs) is rather sucky, but jumping into the world of dependency management will require a deep breath for sure.

Hence, instead of waiting for that, JSON support in un-adorned Postgres to solve a common use case in the interceding years.

The jargon for what this gives you is "a stable oid". Also more or less equivalent to a "system OID" at this time. These "Object IDentifiers" in Postgres are unsigned int32s that are (almost?) never reused (only accrued, or removed), and are all under the number 10000, and all assigned statically by hand. A-priori knowledge of these numbers can simplify writing extensions dramatically, but clearly this is not scalable for a future with dependency chains in extensions.