Oracle 12.2新特性----在線把非分區(qū)表轉(zhuǎn)為分區(qū)表

在Oracle12.2版本之前，如果想把一個非分區(qū)表轉(zhuǎn)為分區(qū)表常用的有這幾種方法：1、建好分區(qū)表然后insert into select 把數(shù)據(jù)插入到分區(qū)表中；2、使用在線重定義(DBMS_REDEFINITION)的方法。它們的幣是：第一種方法，如果對表有頻繁的DML操作，尤其是update操作，就需要停業(yè)務(wù)來做轉(zhuǎn)換。第二種方法可以在線進(jìn)行操作，不需要停業(yè)務(wù)，但操作步驟比較復(fù)雜，且可能出錯。

Oracle12cR2版本中提供了一種新特性，一條語句就可以把非分區(qū)表轉(zhuǎn)換為分區(qū)表，語法如下：

ALTER TABLE table_name MODIFY table_partitioning_clauses
  [ filter_condition ]
  [ ONLINE ]
  [ UPDATE INDEXES [ ( index { local_partitioned_index | global_partitioned_index | GLOBAL }
                     [, index { local_partitioned_index | global_partitioned_index | GLOBAL } ]... )
                   ]
  ]

下面來測試一下這個新特性

1、創(chuàng)建測試表及相關(guān)索引，并查看狀態(tài)

zx@ORA12C>create table emp as select * from scott.emp;

Table created.

zx@ORA12C>create index idx_emp_no on emp(empno);

Index created.

zx@ORA12C>create index idx_emp_job on emp(job);

Index created.

zx@ORA12C>col table_name for a30
zx@ORA12C>col index_name for a30
zx@ORA12C>select table_name,partitioned from user_tables where table_name='EMP';

TABLE_NAME                     PAR
------------------------------ ---
EMP                            NO

zx@ORA12C>select index_name,partitioned,status from user_indexes where table_name='EMP';

INDEX_NAME                     PAR STATUS
------------------------------ --- --------
IDX_EMP_NO                     NO  VALID
IDX_EMP_JOB                    NO  VALID

2、使用alter table語句，執(zhí)行分區(qū)表轉(zhuǎn)換操作

zx@ORA12C>alter table emp modify
  2    partition by range (deptno) interval (10)
  3    ( partition p1 values less than (10),
  4      partition p2 values less than (20)
  5    ) online
  6  ;

Table altered.

3、查看現(xiàn)在的表和索引的狀態(tài)

zx@ORA12C>select table_name,partitioned from user_tables where table_name='EMP';

TABLE_NAME                     PAR
------------------------------ ---
EMP                            YES

zx@ORA12C>select index_name,partitioned,status from user_indexes where table_name='EMP';

INDEX_NAME                     PAR STATUS
------------------------------ --- --------
IDX_EMP_NO                     NO  VALID
IDX_EMP_JOB                    NO  VALID

zx@ORA12C>select table_name,partition_name from user_tab_partitions where table_name='EMP';

TABLE_NAME                     PARTITION_NAME
------------------------------ ------------------------------
EMP                            P1
EMP                            P2
EMP                            SYS_P405
EMP                            SYS_P406

現(xiàn)在表EMP已經(jīng)被轉(zhuǎn)換為分區(qū)表了，索引轉(zhuǎn)換為分區(qū)索引，但索引狀態(tài)是正常的。

4、如果想在轉(zhuǎn)換表時(shí)同時(shí)轉(zhuǎn)換索引可以使用UPDATE INDEXES子句

zx@ORA12C>alter table emp modify
  2    partition by range (deptno) interval (10)
  3    ( partition p1 values less than (10),
  4      partition p2 values less than (20)
  5    ) online
  6    update indexes
  7    (idx_emp_no local)
  8  ;

Table altered.

zx@ORA12C>col table_name for a30
zx@ORA12C>col index_name for a30
zx@ORA12C>select table_name,partitioned from user_tables where table_name='EMP';

TABLE_NAME                     PAR
------------------------------ ---
EMP                            YES

zx@ORA12C>select index_name,partitioned,status from user_indexes where table_name='EMP';

INDEX_NAME                     PAR STATUS
------------------------------ --- --------
IDX_EMP_NO                     YES N/A
IDX_EMP_JOB                    NO  VALID

zx@ORA12C>select table_name,partition_name from user_tab_partitions where table_name='EMP';

TABLE_NAME                     PARTITION_NAME
------------------------------ ------------------------------
EMP                            P1
EMP                            P2
EMP                            SYS_P403
EMP                            SYS_P404

zx@ORA12C>select index_name,partition_name,status from user_ind_partitions where index_name='IDX_EMP_NO';

INDEX_NAME                     PARTITION_NAME                 STATUS
------------------------------ ------------------------------ --------
IDX_EMP_NO                     P1                             USABLE
IDX_EMP_NO                     P2                             USABLE
IDX_EMP_NO                     SYS_P403                       USABLE
IDX_EMP_NO                     SYS_P404                       USABLE

從上面的執(zhí)行結(jié)果來看，不僅表EMP轉(zhuǎn)換為分區(qū)表，而且索引IDX_EMP_NO也轉(zhuǎn)換分區(qū)索引，所有索引狀態(tài)均正常。

下面是官方文檔里的一些注意事項(xiàng)：

When using the UPDATE INDEXES clause, note the following.

• This clause can be used to change the partitioning state of indexes and storage properties of the indexes being converted.

• The specification of the UPDATE INDEXES clause is optional.

  Indexes are maintained both for the online and offline conversion to a partitioned table.

• This clause cannot change the columns on which the original list of indexes are defined.

• This clause cannot change the uniqueness property of the index or any other index property.

• If you do not specify the tablespace for any of the indexes, then the following tablespace defaults apply.

  • Local indexes after the conversion collocate with the table partition.

  • Global indexes after the conversion reside in the same tablespace of the original global index on the non-partitioned table.

• If you do not specify the INDEXES clause or the INDEXES clause does not specify all the indexes on the original non-partitioned table, then the following default behavior applies for all unspecified indexes.

  • Global partitioned indexes remain the same and retain the original partitioning shape.

  • Non-prefixed indexes become global nonpartitioned indexes.

  • Prefixed indexes are converted to local partitioned indexes.

    Prefixed means that the partition key columns are included in the index definition, but the index definition is not limited to including the partitioning keys only.

  • Bitmap indexes become local partitioned indexes, regardless whether they are prefixed or not.

    Bitmap indexes must always be local partitioned indexes.

• The conversion operation cannot be performed if there are domain indexes.

參考：http://docs.oracle.com/database/122/VLDBG/evolve-nopartition-table.htm#VLDBG-GUID-5FDB7D59-DD05-40E4-8AB4-AF82EA0D0FE5