Partition

Partitions are tables that actually store data in a partitioned table. The corresponding entries are usually stored in pg_partition.

The parentid column of each partition is associated with the OIDs of their parent partitioned tables in the pg_class table as a foreign key. For a subpartitioned table, the parentid column of each subpartition is associated with the OIDs of their parent partitions in the pg_partition table as a foreign key.

Example: t1_hash is a partitioned table.

gaussdb=# CREATE TABLE t1_hash (c1 INT, c2 INT, c3 INT)
PARTITION BY HASH(c1)
(
    PARTITION p0,
    PARTITION p1,
    PARTITION p2,
    PARTITION p3,
    PARTITION p4,
    PARTITION p5,
    PARTITION p6,
    PARTITION p7,
    PARTITION p8,
    PARTITION p9
);

-- Query the partitioning type of table t1_hash.
gaussdb=# SELECT oid, relname, parttype FROM pg_class WHERE relname = 't1_hash';
  oid  | relname | parttype
-------+---------+----------
 16685 | t1_hash | p      
(1 row)

-- Query the partition information about table t1_hash.
gaussdb=# SELECT oid, relname, parttype, parentid FROM pg_partition WHERE parentid = 16685;
  oid  | relname | parttype | parentid
-------+---------+----------+----------
 16688 | t1_hash | r        |    16685
 16689 | p0      | p        |    16685
 16690 | p1      | p        |    16685
 16691 | p2      | p        |    16685
 16692 | p3      | p        |    16685
 16693 | p4      | p        |    16685
 16694 | p5      | p        |    16685
 16695 | p6      | p        |    16685
 16696 | p7      | p        |    16685
 16697 | p8      | p        |    16685
 16698 | p9      | p        |    16685
(11 rows)

gaussdb=# DROP TABLE t1_hash;