It makes me wonder if you would have more or less cache misses at the start of a search in an array based BTree (vs potential miss for following some pointers).

It makes me wonder if you would have more or less cache misses at the start of a search in an array based BTree (vs potential miss for following some pointers). However, this is all based on "searching". If you just want to read the latest N values in a timeseries store, then yeah an array or some kind of BRIN index would be better for reads.