Add pg_partition_tree to display information about partitions
 
 
This new function is useful to display a full tree of partitions with a
partitioned table given in output, and avoids the need of any complex
WITH RECURSIVE query when looking at partition trees which are
deep multiple levels.
 
It returns a set of records, one for each partition, containing the
partition's name, its immediate parent's name, a boolean value telling
if the relation is a leaf in the tree and an integer telling its level
in the partition tree with given table considered as root, beginning at
zero for the root, and incrementing by one each time the scan goes one
level down.
 
Author: Amit Langote
 
Discussion: https://postgr.es/m/-9a51-ad02-d53e-@lab.ntt.co.jp