This is an array of partnatts values that
indicate which table columns are part of the partition key. For
example, a value of 1 3 would mean that the first
and the third table columns make up the partition key. A zero in this
array indicates that the corresponding partition key column is an
expression, rather than a simple column reference.
For each column in the partition key, this contains the OID of the
collation to use for partitioning, or zero if the column is not
of a collatable data type.
Expression trees (in nodeToString()
representation) for partition key columns that are not simple column
references. This is a list with one element for each zero
entry in partattrs. Null if all partition key columns
are simple references.