Comment by dunkelheit
4 years ago
It is nice when a program can be significantly sped up by a local change like that but this is not always the case.
To go truly fast, you need to unleash the full potential of the hardware and doing it can require re-architecting the system from the ground up. For example, both postgres and clickhouse can do `select sum(field1) from table group by field2`, but clickhouse will be 100x faster and no amount of microoptimizations in postgres will change that.
No argument from me. I’m just pointing out that it’s wrong to assert that programmers are general incorrect when they say something can be optimized. Many times in my career, optimizations were trivial to implement, and the impact was massive. There have been a few times when the optimization was impossible without a major rearchitecture, but those times were rare.