JOINs rightly get a lot of crap - they are massive performance bottlenecks if you are working with large tables.
Having a single awkward example does not detract from that.
I'll add to this by noting the post does say "For smaller tables it doesn’t matter but as tables get bigger avoid joining when you can" which is sound advice.
I'd say joining scales up to perhaps a million or two rows unless you have a lot of RAM (you can see join spills to disk in the EXPLAIN ANALYZE output). I often am working with tables in the 10-30 million row range so my
perspective is probably a little slanted towards the negative.
Having a single awkward example does not detract from that.
I'll add to this by noting the post does say "For smaller tables it doesn’t matter but as tables get bigger avoid joining when you can" which is sound advice.
I'd say joining scales up to perhaps a million or two rows unless you have a lot of RAM (you can see join spills to disk in the EXPLAIN ANALYZE output). I often am working with tables in the 10-30 million row range so my perspective is probably a little slanted towards the negative.