TsBlock::argMin() and TsBlock::argMin() just return index position and if they are optimized to not perform full decompression we should also ensure that at() doesn't require full decompression with some known index positions:

idx 0 can use fast-path for first

idx count-1 can use fast-path for last

then known index positions for min/max can return the actual data from the min/max fast paths.