Sometimes, you have a large file or input stream that is mostly sorted by some fields with just a few records out of order now and then. You may not care about those few outliers, all you want is most of your data sorted.
Now, you can discard the records out of order, using csv-sort, e.g:
As usual, you can sort by multiple key fields (e.g. csv-sort --discard-out-of-order --fields=a,b,c), sort block by block (e.g. csv-sort --discard-out-of-order --fields=t,block), etc.