The pg_partition_columns system view is used to show the partition key columns of a partitioned table.

    column type references description
    schemaname name The name of the schema the partitioned table is in.
    tablename name The table name of the top-level parent table.
    columnname name The name of the partition key column.
    partitionlevel smallint The level of this subpartition in the hierarchy.
    position_in_partition_key integer For list partitions you can have a composite (multi-column) partition key. This shows the position of the column in a composite key.

    Parent topic: System Catalogs Definitions