PG_HASHBUCKET
PG_HASHBUCKET records hash bucket information.
| 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. |
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