1. Semantic design change
1.1 Naming problem
In 7X, partitions are first-class tables. There is no such thing as alias (partition name) in 7X, therefore pg_partitons.partitionname and pg_partitons.parentpartitionname no longer make sense and not available either.
Take the following table partrl as an example:
-- Classic Syntax
-- Multi-level range-list partitioned table
CREATE TABLE partrl (a int, b int, c int)
DISTRIBUTED BY (a)