I’ve been a Postgres DBA since 2005. After all that time, I’ve come to a conclusion that I’m embarrassed I didn’t reach much earlier: Postgres is awful. This isn’t a “straw that broke the camel’s back” kind of situation; there is a litany of ridiculous idiocy in the project that’s, frankly, more than enough to stave off any DBA, end user, or developer. But I’ll limit my list to five, because clickbait.
A few days ago, a developer came to me with that inevitable scenario that every DBA secretly dreads: a need for a dynamic table structure. After I’d finished dying inside, I explained the various architectures that could give him what he needed, and then I excused myself to another room so I could weep silently without disturbing my coworkers. But was it really that bad? Databases have come a long way since the Bad Old Days when there were really only two viable approaches to table polymorphism.
With Postgres 9.5 on the horizon, I figured it’s a good time to see how things have advanced since my last dive into that particular ocean. This is probably particularly relevant since even MongoDB, a JSON-driven NoSQL database, is now partially powered by Postgres. A lot of people found that particular revelation quite shocking, but maybe they shouldn’t, given the advancements embedded within the last couple of Postgres releases. As it turns out, there are quite a few advancements that really make JSONB a powerful addition to Postgres.
Fairly recently, a friend of mine presented a problem he wanted to solve with some JSON he had in a table. After he presented the end result he was trying to reach, I made the assumption that this would be pretty easy to do. But then I looked at the JSON Functions to try and find that quick fix. Though I read extensively and used rather liberal interpretations of the functions, there’s no way to directly manipulate JSON object contents with PostgreSQL.
With the release of PostgreSQL 9.4, comes the ability to use binary JSON objects. This internal representation is faster and more capable than the original JSON included in 9.3. But how do we actually interact with JSON and JSONB in a database connection context? The answer is actually a little complicated and somewhat surprising. Casting. Casting Everywhere. Despite its inclusion as an internal type, PostgreSQL maintains its position as encouraging explicit casting to avoid bugs inherent in magic type conversions.