The problem with your file is that the date is not ISO i.e. it is not sortable as it is. You have to split it and sort it first on the YYYY, then on MM and, finaly on DD. That's exactly what the following command does. It sorts on the 3rd field from character 7 to character 10 then on char. 4 to 5 etc...
Code:
sort -u -t"|" -k 3.7,3.10n -k 3.4,3.5n -k 3.1,3.2n file
