将global的索引改成分区索引

今天有人在QQ上问，如何将global的索引改成分区索引？由于在同一个列上不能建不同名的索引，不然会报错：

SQL> create index ind_tab2_1 on tab2(a); Index created.   SQL> create index ind_tab2_pindex on tab2(a)   2  local (partition ip1,partition ip2,partition ip3); create index ind_tab2_pindex on tab2(a)                                      * ERROR at line 1: ORA-01408: such column list already indexed

除了删除重建索引外，我们其实可以用在线重定义的方法来重构索引，下面是一个例子：

1. 原表和其索引的建立：

SQL> create table tab2 (a varchar2(20),b varchar2(20),c varchar2(20),d varchar2(20))   2  partition by hash(a)   3  (partition p1,partition p2,partition p3); Table created.   SQL> create index idx_tab2 on tab2(a); Index created.

2. 插入数据：

SQL> insert into tab2 values('aa','bb','cc','dd');   1 row created.   Elapsed: 00:00:02.17 SQL> /   1 row created.   Elapsed: 00:00:00.01 SQL> /   1 row created.   Elapsed: 00:00:00.06 SQL> insert into tab2 select * from tab2;   3 rows created.   Elapsed: 00:00:00.42 SQL> /   6 rows created.   Elapsed: 00:00:00.00 SQL> /   12 rows created.   Elapsed: 00:00:00.03 SQL> /   24 rows created.   Elapsed: 00:00:00.01 SQL> commit;   Commit complete.   Elapsed: 00:00:00.01

3. 创建目标表，且索引是local的分区索引：

SQL> create table tab3 (a varchar2(20),b varchar2(20),c varchar2(20),d varchar2(20))   2  partition by hash(a)   3  (partition p1,partition p2,partition p3);   Table created.   SQL> create index idx_tab1 on tab3(a)   2  local   3  (partition ip1,partition ip2,partition ip3);   Index created.

4. 进行在线重定义，注意我们在这里是用rowid在进行重定义的，因此options_flag=2，不然会报错ora-12089

SQL> exec dbms_redefinition.CAN_REDEF_TABLE('TEST','TAB2'); BEGIN dbms_redefinition.CAN_REDEF_TABLE('TEST','TAB2'); END; * ERROR at line 1: ORA-12089: cannot online redefine table "TEST"."TAB2" with no primary key ORA-06512: at "SYS.DBMS_REDEFINITION", line 137 ORA-06512: at "SYS.DBMS_REDEFINITION", line 1478 ORA-06512: at line 1   SQL> exec dbms_redefinition.CAN_REDEF_TABLE('TEST','TAB2',options_flag=>2); PL/SQL procedure successfully completed.   SQL> exec dbms_redefinition.START_REDEF_TABLE('TEST','TAB2','TAB3',options_flag=>2); PL/SQL procedure successfully completed.

5. 最后完成在线重定义（之前可以多次同步目标表）

SQL> exec dbms_redefinition.FINISH_REDEF_TABLE('TEST','TAB2','TAB3');   PL/SQL procedure successfully completed.   Elapsed: 00:00:09.57 SQL>

至此，tab2表上的global索引已经改成local索引，后续的措施就是rename索引名至正常的索引名和去掉hidden列，在这里就不继续展开了。

 

补充：

索引是一般索引还是分区索引，可以看dba_indexes的partitioned字段。如果partitioned字段是YES，说明是分区索引，那么，这个索引是global还是local，可以看dba_part_indexes的LOCALITY字段。

另外，我们还可以看ALIGNMENT字段，看这个索引是基于前导列（prefixed）还是非前导列。(注：global肯定是基于前导列，因为不能建基于非前导列的global索引。而local索引可以基于前导列和非前导列)

SQL> drop table invoices;

Table dropped.

--创建分区表，是range分区：
SQL> CREATE TABLE invoices
  2  (invoice_no    NUMBER NOT NULL,
  3   invoice_date  DATE   NOT NULL,
  4   invoice_area varchar2(200),
  5   invoice_serial number,
  6   comments      VARCHAR2(500),
  7   invoice_name varchar2(20)
  8   )
  9  PARTITION BY RANGE (invoice_date)
 10  (PARTITION invoices_q1 VALUES LESS THAN (TO_DATE('01/04/2001', 'DD/MM/YYYY')) TABLESPACE users,
 11   PARTITION invoices_q2 VALUES LESS THAN (TO_DATE('01/07/2001', 'DD/MM/YYYY')) TABLESPACE users,
 12   PARTITION invoices_q3 VALUES LESS THAN (TO_DATE('01/09/2001', 'DD/MM/YYYY')) TABLESPACE users,
 13   PARTITION invoices_q4 VALUES LESS THAN (TO_DATE('01/01/2002', 'DD/MM/YYYY')) TABLESPACE users);

Table created.

--创建global分区索引，分区类型可以和表一样，也可以不一样。这个索引是和表分区类型一样，但是value less值不一样。
SQL> CREATE INDEX idx_glob_inv_ser ON invoices (invoice_serial,comments) GLOBAL
  2  PARTITION BY range (invoice_serial)
  3  (PARTITION invoices_q1 VALUES LESS THAN (10) TABLESPACE users,
  4   PARTITION invoices_q2 VALUES LESS THAN (20) TABLESPACE users,
  5   PARTITION invoices_q3 VALUES LESS THAN (30) TABLESPACE users,
  6   PARTITION invoices_q4 VALUES LESS THAN (40) TABLESPACE users,
  7   PARTITION invoices_qmax VALUES LESS THAN (MAXVALUE) TABLESPACE users);

Index created.

--注意global分区索引，必须使用前导列，及如果索引列是 (comments,invoice_serial)，
--但partition by xx(invoice_serial)用了非前导列，是会报错，不能创建成功的。
SQL> CREATE INDEX idx_glob_inv_date ON invoices (comments,invoice_serial) GLOBAL
  2  PARTITION BY hash (invoice_serial) partitions 16;
PARTITION BY hash (invoice_serial) partitions 16
                                 *
ERROR at line 2:
ORA-14038: GLOBAL partitioned index must be prefixed

--创建另一个global分区索引，这个索引的分区类型是和表分区类型不一样的。用了hash分区。但是prefix前导列的原理也是一样的，需要使用前导列。
SQL> CREATE INDEX idx_glob_inv_date ON invoices (comments,invoice_serial) GLOBAL
  2  PARTITION BY hash (comments) partitions 16;

Index created.

--创建local索引，注意不能指定partition by的类型的，local索引的分区类型和分区数量必须和table一致，但是可以指定不同的表空间。这个local使用了前导列。
SQL> CREATE INDEX idx_glo_inv_dt ON invoices (invoice_date,invoice_serial) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users);

Index created.

--如果分区数量必须和table不一致，会报错：
SQL> CREATE INDEX idx_glo_inv_dt ON invoices (invoice_date,invoice_serial) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users,
  6    PARTITION invoices_q5 TABLESPACE users);
CREATE INDEX idx_glo_inv_dt ON invoices (invoice_date,invoice_serial) LOCAL
                               *
ERROR at line 1:
ORA-14024: number of partitions of LOCAL index must equal that of the underlying table

--创建local索引，注，local索引可以使用非前导列。而global索引只能使用前导列，不能使用非前导列。
SQL> CREATE INDEX idx_glo_inv_serl ON invoices (invoice_serial,invoice_date) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users);
Index created.

--如果分区数量必须和table不一致，会报错：
SQL> CREATE INDEX idx_glo_inv_serl ON invoices (invoice_serial,invoice_date) LOCAL
  2   (PARTITION invoices_q1 TABLESPACE users,
  3    PARTITION invoices_q2 TABLESPACE users,
  4    PARTITION invoices_q3 TABLESPACE users,
  5    PARTITION invoices_q4 TABLESPACE users
  6    PARTITION invoices_q5 TABLESPACE users,
  7    PARTITION invoices_q6 TABLESPACE users);
  PARTITION invoices_q5 TABLESPACE users,
  *
ERROR at line 6:
ORA-14010: this physical attribute may not be specified for an index partition

--创建一般索引（即非分区索引）：
SQL> create index idx_glo_inv_comm on invoices (comments);
Index created.

SQL> select index_name,PARTITIONED from dba_indexes where table_name='INVOICES';

INDEX_NAME           PARTIT
-------------------- ------
IDX_GLOB_INV_SER     YES
IDX_GLOB_INV_DATE    YES
IDX_GLO_INV_DT       YES
IDX_GLO_INV_SERL     YES
IDX_GLO_INV_COMM     NO

SQL> select INDEX_NAME,PARTITIONING_TYPE,LOCALITY,ALIGNMENT from dba_part_indexes where table_name='INVOICES';

INDEX_NAME           PARTITIONING_TYPE  LOCALITY     ALIGNMENT
-------------------- ------------------ ------------ ------------------------
IDX_GLOB_INV_SER     RANGE              GLOBAL       PREFIXED
IDX_GLOB_INV_DATE    HASH               GLOBAL       PREFIXED
IDX_GLO_INV_DT       RANGE              LOCAL        PREFIXED
IDX_GLO_INV_SERL     RANGE              LOCAL        NON_PREFIXED

参考 https://oracleblog.org/study-note/partition-index-summary/