PG_HASHBUCKET

PG_HASHBUCKET records hash bucket information.

**Table 1** PG_HASHBUCKET columns
Name	Type	Description
oid	oid	Row identifier (hidden attribute, which must be specified).
bucketid	oid	Node group bound to the database where the PG_HASHBUCKET system catalog resides on the CN. This column is empty on the DN.
bucketcnt	integer	This parameter is not used on the CN. It indicates the number of buckets owned by the current DN on the DN.
bucketmapsize	integer	This parameter is not used in the current version.
bucketref	integer	Reserved column with 1 as its default value.
bucketvector	oidvector_extend	This parameter is not used on the CN. It indicates the list of buckets owned by the current DN on the DN.
bucketmap	text	Stores the mapping between logical buckets and physical buckets, that is, the mapping between 16384 and 1024.
bucketversion	oidvector_extend	Records the version number of the information that changes during subsequent hash bucket scale-out.
bucketcsn	text	Maximum CSN of each bucket on the source node before hash bucket redistribution, which is used to determine the visibility of the new node.
bucketxid	text	next_xid set for bringing a new node online during hash bucket scaling. This parameter is used to check whether the value is within the threshold range.
bucketclogmode	int2	Type of the Clog directory used by a bucket table. If the value is empty, the pg_clog/bucketid directory is used. If the value is 1, the pg_clog/clog_base/dbid/bucketid directory is used.