[exceptione]

Databases are incredibly smart when it comes to fetching related data, a single select is indeed better than splitting queries and doing multiple roundtrips.

The problem however is in how results are returned over the wire. Duplicating rows is needless, but seems to be still the standard.

[moomin]

My experience suggests that they _can_ be good, but this particular pattern they can be remarkably bad at. Source: I keep having to optimise this pattern.

[skeeter2020]

Relational DBs have been around a very long time, and I suspect the processing/transfer time was not the bottleneck, while data access was, so redundant data with the standard relational model wasn't the primary concern.

[kenniskrag]

I think compression would reduce the problem not? I think if you swap the wire format to something like jsonb you would need to parse it again anyway and pay the cpu time.