自Oracle 8（1997年左右）就引入了 分区表&分区索引(Partitioned Tables & Indexes)的概念来调整大表和大索引，提升性能，提升运维管理的能力。分区表和分区索引机制是海量数据库管理（ Very Large Databases ，即VLDB) 中一个重要的提升性能的机制。

Oracle分区技术的历史

Oracle 8引入了分区的概念，后续的每个版本都有对分区机制优化和改进。

使用分区表/索引的好处

• 性能提升： Select语句只检索本分区的记录，减少了记录总数，可有效的提升了查询性能。另外，可以通过表空间将分区映射到不同的物理磁盘上，分散设备IO，提升性能；
• 分区运维：可以针对不同分区，管理数据的加载、索引的创建(以及重建)、数据备份与恢复。因为可针对分区的管理，所以可以有效的降低了分区间的干扰、影响。

更多分区的好处可以阅读 Oracle Partitioning这篇文章，写的更加详细些。

什么时候使用分区表

什么时候使用分区表，并没有一个精确的界限，Oracle只有一些 通用的建议，具体使用需要自行评估：    

• Tables greater than 2GB should always be considered for partitioning.
• Tables containing historical data, in which new data is added into the newest partition. A typical example is a historical table where only the current month's data is updatable and the other 11 months are read only.

Tip: 计算表大小的SQL SELECT B.OWNER,        B.TABLESPACE_NAME,        B.TABLE_NAME,        ROUND (SUM (BYTES) / 1024 / 1024 / 1024, 6) GIGS FROM   SYS.DBA_EXTENTS A, SYS.DBA_TABLES B WHERE ((B.TABLESPACE_NAME = A.TABLESPACE_NAME)                 AND (B.OWNER = UPPER ('&OWNER')) AND (B.TABLE_NAME = '&TABLE')) GROUP BY B.OWNER, B.TABLESPACE_NAME, B.TABLE_NAME;

分区表的索引可以是分区索引，也可以是非分区索引（普通索引）。

如何分区（分区的方法）

Partition Key

分区表/索引是以一个或多个字段为依据来决定记录存储在哪个分区，被选用的分区字段称为Partition Key，Oracle会根据Partition Key自动找到对应的分区中做insert, update, delete操作。

分区的方法

Oracle提供了6种分区方法：

Partitioning Method	Brief Description
Range Partitioning	Used when there are logical ranges of data. Possible usage: dates, part numbers, and serial numbers
Hash Partitioning	Used to spread data evenly over partitions. Possible usage: data has no logical groupings
List Partitioning	Used to list together unrelated data into partitions. Possible usage: a number of states list partitioned into a region
Composite Range-Hash Partitioning	Used to range partition first, then spreads data into hash partitions. Possible usage: range partition by date of birth then hash partition by name; store the results into the hash partitions
Composite Range-List Partitioning	Used to range partition first, then spreads data into list partitions.Possible usage: range partition by date of birth then list partition by state, then store the results into the list partitions

Examples

Range Partitioning Example

--创建表空间

create tablespace invoices_2010 datafile 'e:\app\TianPan\oradata\tbs01.dbf' size 50m;
create tablespace invoices_2011 datafile 'e:\app\TianPan\oradata\tbs02.dbf' size 50m;
create tablespace invoices_2012 datafile 'e:\app\TianPan\oradata\tbs03.dbf' size 50m;
create tablespace invoices_2013 datafile 'e:\app\TianPan\oradata\tbs04.dbf' size 50m;
--创建Range类型的分区表
CREATE TABLE Invoices(
    Invoice_NO VARCHAR2(10),
    Invoice_Creation_Day DATE,
    Invoice_Data VARCHAR2(30)
)
PARTITION BY RANGE(Invoice_Creation_Day)
(  
PARTITION part01 VALUES LESS THAN(TO_DATE('2010-12-31 00:00:00','yyyy-mm-dd hh24:mi:ss')) TABLESPACE invoices_2010,
PARTITION part02 VALUES LESS THAN(TO_DATE('2011-12-31 00:00:00','yyyy-mm-dd hh24:mi:ss')) TABLESPACE invoices_2011,
PARTITION part03 VALUES LESS THAN(TO_DATE('2012-12-31 00:00:00','yyyy-mm-dd hh24:mi:ss')) TABLESPACE invoices_2012,
PARTITION part04 VALUES LESS THAN (MAXVALUE) TABLESPACE invoices_2013
);
--按年插入测试数据
insert into Invoices values('1',TO_DATE('2010-06-10 00:00:00','yyyy-mm-dd hh24:mi:ss'), '2010 invoice');
insert into Invoices values('2',TO_DATE('2011-07-20 00:00:00','yyyy-mm-dd hh24:mi:ss'), '2011 invoice');
insert into Invoices values('3',TO_DATE('2012-08-25 00:00:00','yyyy-mm-dd hh24:mi:ss'), '2012 invoice');
insert into Invoices values('4',TO_DATE('2013-08-25 00:00:00','yyyy-mm-dd hh24:mi:ss'), '2013 invoice');
commit;
--查询确认，是不是数据被存储到正确的分区

SQL> select * from Invoices;
INVOICE_NO INVOICE_CREATION_DAY INVOICE_DATA
---------- -------------------- ------------------------------
1          2010/6/10            2010 invoice
2          2011/7/20            2011 invoice
3          2012/8/25            2012 invoice
4          2013/8/25            2013 invoice

SQL> select * from Invoices partition(part01);
INVOICE_NO INVOICE_CREATION_DAY INVOICE_DATA
---------- -------------------- ------------------------------
1          2010/6/10            2010 invoice

SQL> select * from Invoices partition(part02);
INVOICE_NO INVOICE_CREATION_DAY INVOICE_DATA
---------- -------------------- ------------------------------
2          2011/7/20            2011 invoice

List Partitioning Example

--创建表空间
create tablespace TS01 datafile 'e:\app\TianPan\oradata\list\tbs01.dbf' size 50m;
create tablespace TS02 datafile 'e:\app\TianPan\oradata\list\tbs02.dbf' size 50m;
create tablespace TS03 datafile 'e:\app\TianPan\oradata\list\tbs03.dbf' size 50m;
create tablespace TS04 datafile 'e:\app\TianPan\oradata\list\tbs04.dbf' size 50m;
create tablespace TS05 datafile 'e:\app\TianPan\oradata\list\tbs05.dbf' size 50m;
--把不同的州划分到不同的分区(表空间)中
CREATE TABLE PARTITION_BY_LIST
(DEPTID            NUMBER,
DEPTNAME        VARCHAR2(15),
STATE            VARCHAR2(2) ,
CONSTRAINT PARTITION_BY_LIST_PK PRIMARY KEY (DEPTID))
PARTITION BY LIST (STATE)
(PARTITION DEPTS_IN_NORTH VALUES ('AK')                    TABLESPACE TS01,
PARTITION DEPTS_IN_EAST  VALUES ('NY', 'NJ', 'VA', 'CT')  TABLESPACE TS02,
PARTITION DEPTS_IN_SOUTH VALUES ('TX', 'MS', 'GA', 'KY')  TABLESPACE TS03,
PARTITION DEPTS_IN_WEST  VALUES ('CA', 'AZ', 'OR', 'NV')  TABLESPACE TS04,
PARTITION DEPTS_WITH_NO_REGION VALUES (DEFAULT)           TABLESPACE TS05)
ENABLE ROW MOVEMENT;
--检查分区是否创建正确
SELECT TABLE_NAME, PARTITION_NAME, HIGH_VALUE, TABLESPACE_NAME
FROM USER_TAB_PARTITIONS
WHERE TABLE_NAME = 'PARTITION_BY_LIST'
ORDER BY TABLESPACE_NAME;
--插入测试数据
INSERT INTO PARTITION_BY_LIST (DEPTID, DEPTNAME, STATE) VALUES (1,'ANCHORAGE'  , 'AK');
INSERT INTO PARTITION_BY_LIST (DEPTID, DEPTNAME, STATE) VALUES (2,'NEW YORK'   , 'NY');
INSERT INTO PARTITION_BY_LIST (DEPTID, DEPTNAME, STATE) VALUES (3,'DALLAS'     , 'TX');
INSERT INTO PARTITION_BY_LIST (DEPTID, DEPTNAME, STATE) VALUES (4,'LOS ANGELES', 'CA');
INSERT INTO PARTITION_BY_LIST (DEPTID, DEPTNAME, STATE) VALUES (5,'WAIKIKI'    , 'HI');
COMMIT;
--查询确认，是不是数据被存储到正确的分区
SQL> select * from PARTITION_BY_LIST;
    DEPTID DEPTNAME        STATE
---------- --------------- -----
         1 ANCHORAGE       AK
         2 NEW YORK        NY
         3 DALLAS          TX
         4 LOS ANGELES     CA
         5 WAIKIKI         HI

SQL> select * from PARTITION_BY_LIST partition (depts_in_north);
    DEPTID DEPTNAME        STATE
---------- --------------- -----
         1 ANCHORAGE       AK

SQL> select * from PARTITION_BY_LIST partition (depts_in_east);
    DEPTID DEPTNAME        STATE
---------- --------------- -----
         2 NEW YORK        NY

SQL> select * from PARTITION_BY_LIST partition (depts_with_no_region);
    DEPTID DEPTNAME        STATE
---------- --------------- -----
         5 WAIKIKI         HI

Useful Query

[Query]如何知道一个表或索引是否有被分区

SELECT * FROM dba_part_tables;
SELECT * FROM dba_part_indexes;

[Query]如何列出分区表或索引的分区对象

SELECT * FROM dba_tab_partitions WHERE table_name = '<table_name>';
SELECT * FROM dba_ind_partitions WHERE index_name = '<index_name>';

分区表的数据导出导入

全表导出

C:\Users\TianPan>exp system/welcome@ptian file=c:\test.dmp tables=Invoices

Export: Release 11.2.0.1.0 - Production on Fri Jan 9 16:18:05 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export done in ZHS16GBK character set and AL16UTF16 NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                       INVOICES
. . exporting partition                         PART01          1 rows exported
. . exporting partition                         PART02          1 rows exported
. . exporting partition                         PART03          1 rows exported
. . exporting partition                         PART04          1 rows exported
Export terminated successfully without warnings.

分区表导出

C:\Users\TianPan>exp system/welcome@ptian file=c:\test_part.dmp tables=Invoices:part03

Export: Release 11.2.0.1.0 - Production on Fri Jan 9 16:21:04 2015

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export done in ZHS16GBK character set and AL16UTF16 NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                       INVOICES
. . exporting partition                         PART03          1 rows exported
Export terminated successfully without warnings.

全表导入

imp system/welcome@ptian file=test.dmp full=y

分区表导入

imp system/welcome@ptianfile=test_part.dmp full=y

数据泵expdp/impdp的方式

导出整个表
expdp scott/tiger directory=dmp dumpfile=tb_pt.dmp logfile=tb_pb.log tables=tb_pt parallel=3
导出多个分区
expdp scott/tiger directory=dmp dumpfile=tb_pts.dmp logfile=tb_pt.log tables=(tb_pt:sal_16,tb_pt:sal_other) parallel=2

导入单个分区
impdp scott/tiger directory=dmp dumpfile=tb_pts.dmp logfile=tb_pt_imp.log tables=tb_pt:sal_other skip_unusable_indexes=y table_exists_action=replace
导入整个表
impdp scott/tiger directory=dmp dumpfile=tb_pt.dmp logfile=tb_pt_fullimp.log tables=tb_pt skip_unusable_indexes=y table_exists_action=replace

参考：

Partitioned Tables And Indexes 

Partitioning an Oracle table Tips

Oracle Partitioned Tables & Indexes 

Oracle® Database VLDB and Partitioning Guide

All about Partitions 

Oracle Partitioning 

Partitioning

Partitioning FAQ

New Whitepaper: Database Partitioning for the E-Business Suite

Using Database Partitioning with the E-Business Suite 

Oracle Metalink Note:  554539.1 - Using Database Partitioning with Oracle E-Business Suite