clu는 user_clusters의 동의어임
【예제】
SQL> desc dba_clusters;
Name Null? Type
----------------------------------------- -------- ----------------------------
OWNER NOT NULL VARCHAR2(30)
CLUSTER_NAME NOT NULL VARCHAR2(30)
TABLESPACE_NAME NOT NULL VARCHAR2(30)
PCT_FREE NUMBER
PCT_USED NUMBER
KEY_SIZE NUMBER
INI_TRANS NOT NULL NUMBER
MAX_TRANS NOT NULL NUMBER
INITIAL_EXTENT NUMBER
NEXT_EXTENT NUMBER
MIN_EXTENTS NOT NULL NUMBER
MAX_EXTENTS NOT NULL NUMBER
PCT_INCREASE NUMBER
FREELISTS NUMBER
FREELIST_GROUPS NUMBER
AVG_BLOCKS_PER_KEY NUMBER
CLUSTER_TYPE VARCHAR2(5)
FUNCTION VARCHAR2(15)
HASHKEYS NUMBER
DEGREE VARCHAR2(20)
INSTANCES VARCHAR2(20)
CACHE VARCHAR2(10)
BUFFER_POOL VARCHAR2(7)
SINGLE_TABLE VARCHAR2(10)
DEPENDENCIES VARCHAR2(8)
SQL> select count(*) from dba_clusters;
COUNT(*)
----------
10
SQL> select count(*) from user_clusters;
COUNT(*)
----------
10
SQL> desc user_clusters;
Name Null? Type
----------------------------------------- -------- ----------------------------
CLUSTER_NAME NOT NULL VARCHAR2(30)
TABLESPACE_NAME NOT NULL VARCHAR2(30)
PCT_FREE NUMBER
PCT_USED NUMBER
KEY_SIZE NUMBER
INI_TRANS NOT NULL NUMBER
MAX_TRANS NOT NULL NUMBER
INITIAL_EXTENT NUMBER
NEXT_EXTENT NUMBER
MIN_EXTENTS NOT NULL NUMBER
MAX_EXTENTS NOT NULL NUMBER
PCT_INCREASE NUMBER
FREELISTS NUMBER
FREELIST_GROUPS NUMBER
AVG_BLOCKS_PER_KEY NUMBER
CLUSTER_TYPE VARCHAR2(5)
FUNCTION VARCHAR2(15)
HASHKEYS NUMBER
DEGREE VARCHAR2(20)
INSTANCES VARCHAR2(20)
CACHE VARCHAR2(10)
BUFFER_POOL VARCHAR2(7)
SINGLE_TABLE VARCHAR2(10)
DEPENDENCIES VARCHAR2(8)
SQL>
【예제】
SQL> create cluster cluster_t1_t2( idnum number(3));
Cluster created.
SQL> create index ind_cluster_t1_t2
2 on cluster cluster_t1_t2;
Index created.
SQL> create table t1(
2 name varchar2(10),hiredate date,
3 idnum number(3))
4 cluster cluster_t1_t2(idnum); ☜ 클러스터 키를 지정
Table created.
SQL> create table t2(idnum number(3),idname varchar2(10))
2 cluster cluster_t1_t2(idnum); ☜ 클러스터 키를 지정
Table created.
SQL> select * from tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
CLUSTER_T1_T2 CLUSTER
EMP TABLE
EMPLOYEES TABLE
T1 TABLE 1
T2 TABLE 2
SQL> select rowid from t1;
ROWID
------------------
AAAHcGAABAAAMXCAAA ☜ t1 테이블의 데이터 위치 확인(t2과 같음)
SQL> select rowid from t2;
ROWID
------------------
AAAHcGAABAAAMXCAAA ☜ t2 테이블의 데이터 위치 확인(t1과 같음)
SQL> drop cluster cluster_t1_t2
2 including tables; ☜ 클러스터 삭제
Cluster dropped.
SQL> select * from tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
EMP TABLE
EMPLOYEES TABLE
SQL> select * from user_clusters; ☜ 클러스터 확인
all_clusters