On 13rd of November 2020, Tom Lane committed patch:
Support negative indexes in split_part(). This provides a handy way to get, say, the last field of the string. Use of a negative index in this way has precedent in the nearby left() and right() functions. The implementation scans the string twice when N < -1, but it seems likely that N = -1 will be the huge majority of actual use cases, so I'm not really excited about adding complexity to avoid that. Nikhil Benesch, reviewed by Jacob Champion; cosmetic tweakage by me Discussion: https://firstname.lastname@example.org
Continue reading Waiting for PostgreSQL 14 – Support negative indexes in split_part().