# pg_vcluster

System table `pg_vcluster`  contains information about the virtual cluster(VC).`pg_vcluster` is a shared table.

In OushuDB, segment nodes can be devided into several VCs. In a virtual cluster, there are homogeneous multiple virtual computing cluster instances(VCI).`pg_vcluster` contains the definition of vcs and vcis.



Table 1. `pg_catalog.pg_vcluster`

| column       | type      | references | description                                                  |
| :----------- | :-------- | :--------- | :----------------------------------------------------------- |
| `vcname`     | name      |            | name of vc/vci. Because one vci belongs to one vc, vci's name likes 'vcname@vciname'. |
| `vcseg`      | text[]    |            | only for vci. Ip or hostname of segment belongs to vci.      |
| `properties` | text      |            | properties of vc<br />hash_table_bucket_number="8", <br />max_nvseg_perquery="512", <br />max_nvseg_perquery_perseg="8", <br />enforce_nvseg="0", <br />enforce_memory_pervseg="0", <br />magma_hash_table_nvseg_perseg="8", <br />nvseg_per_vci="0"<br /> |
| `ip`         | text      |            | location of rm process                                       |
| `vcowner`    | oid       |            | owner of vc                                                  |
| `vcacl`      | aclitem[] |            | acl information of vc                                        |