Do people really still do online SQL joins for read type queries that tolerate eventual consistency (this is the most common type of read btw)?
If so, why do joins? Why not materialise the correct shape of the data and use it directly? Surely storage is cheaper than having to spend compute doing online joins. Doesn't doing joins online hurt latency?
I could be missing something obvious. But if I am right, in what case do online joins make sense?
_se•1w ago
The performance is, in general, significantly worse than standard OLTP joins for most real-time use-cases.
There's very little reason to avoid an OLTP join. It's faster than anything you're likely to be able to implement yourself, and the compute required with proper indices is negligible.
You're asking the wrong question, because really the question is where do they _not_ make sense, which is almost nowhere.