1. Partitioning – Let’s Divide and Conquer!
Gavin Soorma,
Senior Oracle DBA, Bankwest

2. Agenda The what, who and why of Partitioning
Partitioning – decisions and challenges
Partitioning – It’s evolution
Types of Partitioning
What’s new in Oracle11g?
Partitioned Indexes
Composite Partitioning
Partition Maintenance Operations
Partitioning and the Cost-based Optimizer
Converting a non-partitioned table to a partitioned table

3. What is Partitioning?
a) A Structure dividing a space into parts (noun)
b) To divide or separate (verb)
Source: Oxford English Dictionary
Additional licensable option of the Oracle Enterprise Edition.
Partitioning allows a table, index or index-organized table to be divided and subdivided into smaller pieces called partitions and sub-partitions.
A partitioned object has multiple pieces that can be managed either collectively or individually.
Each partition has its own name, and may optionally have its own storage characteristics.
Tables are partitioned using a 'partitioning key', a set of column/columns which determine in which partition a given row will reside.

4. Partitioning stores a data segment (Table, Index, LOB) as
multiple segments while retaining a logically massive
structure.
Really Big
Table
Partition
Partition
Partition
Partition
Partition
Partition
Really Big Table
Partition
Partition
Partition
Partition
Partition
Partition
Partition
Partition

5. Who Partitions?
Deciding on what and how to partition is both a Developer and DBA job.
A good of understanding of the business rules needs to be known about how the data is utilized within Oracle. For example, how data is loaded and queried by the application?
A great portion of care needs to done in selection of the type of partitioning along with the partition key.
Poor selection of partition or partition key could lead to poor DML and DDL performance.
Always test, test, and test again prior to implementing in production.

6. Why Partition? For Manageability For Performance For Availability
Partitioning enables data management operations such data loads, index creation and rebuilding, and backup/recovery at the partition level, rather than on the entire table. This results in significantly reduced times for these operations.
For Performance
Partitioning improves query performance. In many cases, the results of a query can be achieved by accessing a subset of partitions, rather than the entire table. Partition Pruning and Partition-wise joins can provide order-of-magnitude gains in performance.
For Availability
Partitioning increases the availability of mission-critical databases if critical tables and indexes are divided into partitions to reduce the maintenance windows, recovery times, and impact of failures.

7. Decisions and Challenges
License cost of Partitioning option (~11,000$ per CPU)
Number of Partitions.
Choosing the partitioning key column.
Partitioning Key – single column, multiple column.
Choosing the type of partitioning: Range, Hash-List, Range-Hash, Range-List, List-List, Range-Range ….
Which tables to Partition …. All tables > 2GB (Oracle says so …)
Think about it if table is > 1 million rows (I say so …)
Partitioned tables with non partitioned or partitioned index
Global Index vs Local Index

8. Oracle Partitioning 10 years of innovation…
Database Release
Core Functionality
Oracle 8.0 (1997)
Range Partitioning
Oracle 8i
Hash and Composite Partitioning
Oracle 9i
List Partitioning
Oracle 9i Release 2
Composite Range-List Partitioning
Oracle 10g
Global Hash Indexes
Oracle 10g Release 2
1M partitions per table
Oracle 11g
Interval Partitioning, System Partitioning, REF Partitioning, Virtual Column Partitioning, Partition Advisor , Composite All Partitioning

9. Partitioning Methods
Oracle provides the following partitioning methods(pre 11g):
Range Partitioning
List Partitioning
Hash Partitioning
Composite Partitioning
Composite Partitioning is a combination of the methods shown above

10. Composite Partitioning
Range-Hash
Partitioned by date_of_sale
then ….
Partitioned by salesman_id
Range-List
Partitioned by date_of_sale
then ….
Partitioned by sales_region

11. RANGE Partitioning Introduced in Oracle 8.0
Useful when Data has logical ranges into which it can be distributed by – example, a range of dates
Data is mapped to partitions based on ranges of partition key values established for each partition
Each partition has a VALUES LESS THAN clause, which specifies a non inclusive upper bound for the partitions.
All partitions, except the first, have an implicit lower bound specified by the VALUES LESS THAN clause on the previous partition
A MAXVALUE literal can be defined for the highest partition. MAXVALUE represents a virtual infinite value

12. Partition descriptions identifying partition bounds
Range Partitioning
Partitioning Method
create table order_details
(order_id number,
order_date date)
partition by range (order_date)
(partition p_jan values less than (to_date('01-FEB-2009','DD-MON-YYYY')),
partition p_feb values less than (to_date('01-MAR-2009','DD-MON-YYYY')),
partition p_mar values less than (to_date('01-APR-2009','DD-MON-YYYY')),
partition p_2009 values less than (MAXVALUE) ) ;
Partitioning Column (Key)
Partition descriptions identifying partition bounds

13. Hash Partitioning
Introduced in Oracle 8i.
Enables partitioning of data that does not lend itself to either range or list partitioning
As a better alternative to range partitioning when:
We do not know beforehand how much data maps to a particular range.
The size of range partitions would differ substantially.
Range partitioning would cause the data to be undesirably clustered.

14. Hash Partitioning
Hash function applied to the partitioning key column to place row in required partition.
Balances the data distribution between all partitions.
Is an effective means of distributing data, because Oracle hashes the data into a number of partitions, each of which can reside on a separate device.
Hash Partitioning enables the use of performance features like Partition-wise joins when two tables are hash partitioned on the join key.

15. Hash Partitioning Not suitable for purging and archiving data models.
Partition pruning is limited to using equality or IN-list predicates.
User has no control of the row to partition mapping.
Partition maintenance tasks like splitting, dropping and merging cannot be carried out.
Partitions can only be added and coalesced.

16. CREATE TABLE employees (
empno NUMBER(4),
ename VARCHAR2(30),
sal NUMBER )
PARTITION BY HASH (empno) (
PARTITION h1 TABLESPACE t1,
PARTITION h2 TABLESPACE t2,
PARTITION h3 TABLESPACE t3,
PARTITION h4 TABLESPACE t4 );
PARTITION BY HASH(empno)
PARTITIONS 3
STORE IN (t1,t2,t3) ;

17. List Partitioning Introduced in Oracle 9i.
List Partitioning is useful for data that has discrete or distinct values.
Enables to group and organize unordered and unrelated sets of data.
Gives data warehouse administrators precise control over which data belongs in each partition.
Enables the partitioning strategy to closely model underlying business processes.
Unlike range and hash partitioning, multicolumn partition keys are not supported for list partitioning.

18. CREATE TABLE sales_list
(salesman_id NUMBER(5),
salesman_name VARCHAR2(30),
sales_state VARCHAR2(20),
sales_amount NUMBER(10),
sales_date DATE)
PARTITION BY LIST(sales_state) (
PARTITION sales_west VALUES ('California', 'Hawaii'),
PARTITION sales_east VALUES ('New York', 'Virginia', 'Florida'),
PARTITION sales_central VALUES ('Texas', 'Illinois'),
PARTITION sales_other VALUES (DEFAULT) );

19. 11g Interval partitioning
Pre 11g new partitions must be created in advance for new data.
Additional partitioning management overhead.
11g interval partitioning automates partition management.
Extension of range partitioning.
Automatic creation of range partitions based on interval.
Segments are allocated as soon as new data arrives.
Local indexes are created and maintained as well

20. CREATE TABLE order_details (order_id NUMBER, order_date DATE)
PARTITION BY RANGE (order_date)
INTERVAL (NUMTOYMINTERVAL(1,'MONTH'))
(PARTITION P_FIRST VALUES LESS THAN ('01-JAN-2009')) ;
SQL> select partition_name from user_tab_partitions
where table_name='ORDER_DETAILS';
PARTITION_NAME
P_FIRST

21. SQL> insert into order_details
values
(10001,'15-JAN-2009');
1 row created.
SQL> commit;
Commit complete.
SQL> select partition_name from user_tab_partitions
where table_name='ORDER_DETAILS';
PARTITION_NAME
P_FIRST
SYS_P101

22. REF Partitioning
Related tables benefit from the same partitioning strategy.
Example:Orders and Line Items table
Redundant storage of the same data solves the problem.
But Data and maintenance overhead …
Oracle 11g introduces REF partitioning
Child table inherits the same partitioning strategy as the parent table via PK-FK relationships.
Enhanced performance as well as manageability.
Partition maintenance operations on parent table cascade to child table.

23. Before REF Partitioning
Table ORDERS
RANGE
(order_date) … …
PRIMARY KEY
(order_id)
Jan 2009
Feb 2009
Dec 2009
Redundant storage of order_date
Table LINEITEMS
RANGE
(order_date)
FOREIGN KEY
(order_id) … …
Jan 2009
Feb 2009
Dec 2009

24. 11g REF Partitioning … Table ORDERS RANGE (order_date) … PRIMARY KEY
(order_id)
Jan 2009
Feb 2009
Partition By Reference
Partitioning Key in Child Table
Inherited through PK-FK
relationship
Table LINEITEMS
RANGE
(order_date)
FOREIGN KEY
(order_id) … …
Jan 2009
Feb 2009

25. CREATE TABLE mycustomers
(cust_id NUMBER,
cust_first_name VARCHAR2(20),
cust_last_name VARCHAR2(20),
cust_gender CHAR(1))
PARTITION BY LIST (cust_gender)
(PARTITION p_male VALUES ('M'),
PARTITION p_female VALUES ('F') );
SQL> ALTER TABLE mycustomers ADD CONSTRAINT p_cust_id PRIMARY KEY (cust_id);
Table altered.

26. CREATE TABLE mysales
(cust_id NUMBER NOT NULL, quantity_sold NUMBER(10,2),
amount_sold NUMBER(10,2),
CONSTRAINT fk_sales_01
FOREIGN KEY (cust_id)
REFERENCES mycustomers(cust_id))
PARTITION BY REFERENCE (fk_sales_01);
SQL> SELECT TABLE_NAME, PARTITIONING_TYPE,
REF_PTN_CONSTRAINT_NAME FROM USER_PART_TABLES WHERE
TABLE_NAME IN ('MYCUSTOMERS','MYSALES');
TABLE_NAME PARTITION REF_PTN_CONSTRAINT_NAME
MYCUSTOMERS LIST
MYSALES REFERENCE FK_SALES_01

27. Extended Composite Partitioning
Data is partitioned along two dimesions
Introduced in Oracle 8i with Range/Hash
9i extended to Range/List
11g extended to all combinations
Range
List
Hash
11g 9i 8i
Range/Range Order Date, Shipping Date
List/Range Salesman, Date of Sale
List/List State, County

28. Range-Range Partitioning
Ship_date …
Jan 08
Feb 08 … … … … …
Dec 08 … … … … …
Jan 08
Feb 08
Mar 08
Dec 08
Order_date

29. 11g Virtual Column Partitioning
Virtual columns introduced in Oracle 11g.
Virtual columns using functions and expressions.
Virtual column not stored physically.
Partition data as per business rules and requirements – not just based on application requirements.
Treated as real columns – only DML not allowed.
Enhanced performance and manageability

30. CREATE TABLE emp_year_sal
(ename VARCHAR2(20),
sal NUMBER,
yearly_sal AS (sal*12) VIRTUAL)
PARTITION BY RANGE (yearly_sal)
(PARTITION low_sal VALUES LESS THAN (20000),
PARTITION mid_sal VALUES LESS THAN (40000),
PARTITION high_sal VALUES LESS THAN (60000),
PARTITION others VALUES LESS THAN (MAXVALUE));
SQL> SELECT ename,sal,yearly_sal FROM emp_year_sal;
ENAME SAL YEARLY_SAL
SMITH
ALLEN
WARD
JONES
MARTIN
BLAKE
CLARK
SCOTT

31. SQL> SELECT ename,sal,yearly_sal FROM emp_year_sal PARTITION (low_sal);
SMITH
ALLEN
WARD
MARTIN
TURNER
ADAMS
SQL> SELECT ename,sal,yearly_sal FROM emp_year_sal PARTITION(mid_sal);
JONES
BLAKE
CLARK
SCOTT
FORD

32. 10g Partitioning - Summary
Partitioning Strategy
Data Distribution
Sample Business Usage
Range Partitioning
Based on consecutive ranges of values
Orders table range
partitioned by order_date
List Partitioning
Based on unordered lists of
values.
Orders table list partitioned
by country
Hash Partitioning
Based on a hash algorithm.
Orders table hash partitioned
by customer_id
Composite Partitioning
Range-Range
Range-List
Range-Hash
List-List
List-Range
List-Hash
Based on a combination of two of the above-mentioned basic
techniques of Range, List,
Hash, and Interval Partitioning
Orders table is range
and sub-partitioned by hash
on customer_id
and sub-partitioned by range
on shipment_date

33. 11g Partitioning - Summary
Partitioning Extension
Partitioning Key
Sample Business Usage
Interval Partitioning
Interval
Interval-Range
Interval-List
Interval-Hash
An extension to Range
Partition. Defined by an
interval, providing equi-width
ranges. With the exception of
the first partition all partitions
are automatically created ondemand
when matching data
arrives.
Orders table partitioned by
order_date with a predefined
daily interval, starting with
'01-Jan-2007'
REF Partitioning
Partitioning for a child table is
inherited from the parent table
through a primary key –
foreign key relationship. The
partitioning keys are not stored
in actual columns in the child
table.
(Parent) Orders table range
partitioned by order_date
and inherits the partitioning
technique to (child) order
lines table. Column
order_date is only present in
the parent orders table
Virtual column based
Partitioning
Defined by one of the abovementioned
partition techniques
and the partitioning key is
based on a virtual column.
Virtual columns are not stored
on disk and only exist as
metadata.
Orders table has a virtual
column that derives the sales
region based on the first
three digits of the customer
account number. The orders
table is then list partitioned
by sales region.

34. Partition Data Dictionary Views
DBA_PART_TABLES
DBA_TAB_PARTITIONS
DBA_TAB_SUBPARTITIONS
DBA_PART_KEY_COLUMNS
DBA_PART_HISTOGRAMS
DBA_PART_INDEXES
DBA_IND_PARTITIONS DBA_IND_SUBPARTITIONS

35. Working with Partitions
SQL> select order_date from order_details partition(p_jan);
SQL> select count(*) from SALES_DATA_COMP subpartition(SALES_2000_SP2);
$ exp system/manager TABLES=(order_details:p_jan)
$ exp system/manager TABLES=(order_details:p_jan, order_details:p_jan_subpart1)

36. Local and Global Indexes
LOCAL INDEX
Index partition
equipartitioned
with table
Single index partition
only contains rows from
corresponding table partition
GLOBAL INDEX
Index partition can
contain rows from
several table
partitions

37. LOCAL Partitioned Index
Equi-partitioned – each partition of local index exactly associated with corresponding partition of the table.
Cannot explicitly add or drop local index partitions – partitions to the index are added or dropped based on partitions being added or dropped from base table.
Provide higher availability and ease of maintenance.
Partition maintenance operations on base table will only affect corresponding local index partition – other partitions of the index are not affected improving availability.
Most suited for DSS environments - easier to manage during data loads and during partition-maintenance operations

38. SQL> select partition_name from user_tab_partitions where table_name='ORDER_DETAILS';
P_FIRST
SYS_P81
SYS_P82
SQL> create index order_det_ind_local on order_details (order_date)
LOCAL << NO PARTITIONING KEY DEFINED
(partition p1_ind tablespace users,
partition p2_ind tablespace example);
create index order_det_ind_local on order_details (order_date) *
ERROR at line 1:
ORA-14024: number of partitions of LOCAL index must equal that of the underlying table

39. SQL> create index order_det_ind_local on order_details (order_date)
tablespace example;
Index created.
SQL> select partition_name,tablespace_name from user_ind_partitions where index_name='ORDER_DET_IND_LOCAL';
PARTITION_NAME TABLESPACE_NAME
P_FIRST EXAMPLE
SYS_P EXAMPLE
SYS_P EXAMPLE

40. Global Partitioned Index
Index partitioning key is independent of the table partitioning method.
Better suited for OLTP environments than local indexes.
Better performance as they minimise the number of index partition probes.
Lower availability than local indexes as partition maintenance operations can affect all the index partitions.

41. Global Partitioned Indexes
Highest partition of the global index needs to have a MAXVALUE clause to ensure all rows of the underlying table are represented – this partition cannot be dropped.
Can be created as a global hash or global range partitioned index.
Can enable partition pruning to take place at the index level even if not possible on the underlying partitioned table

42. Table Partitioned on order_date CREATE INDEX order_id_ind_global
ON order_details (order_id)
GLOBAL PARTITION BY RANGE (order_id)
(PARTITION p_ind1 values less than (100001),
PARTITION p_ind2 values less than (200001),
PARTITION p_ind3 values less than (300001)); PARTITION p_ind3 values less than (300001)) *
ERROR at line 6:
ORA-14021: MAXVALUE must be specified for all columns
Table Partitioned
on order_date
CREATE INDEX order_id_ind_global
ON order_details (order_id)
GLOBAL PARTITION BY RANGE (order_id)
(PARTITION p_ind1 values less than (100001),
PARTITION p_ind2 values less than (200001),
PARTITION p_ind3 values less than (300001),
PARTITION p_ind_others values less than (MAXVALUE));

43. Partition Maintenance Operations
Add
Coalesce
Drop
Truncate
Split
Exchange
Move
Rename
Merge ….
Consider the effect of these operations on Index partitions …..

44. Partition Maintenance
ALTER TABLE sales ADD PARTITION jan96 VALUES LESS THAN ( '01-FEB-1999' ) TABLESPACE tsx;
ALTER TABLE scubagear ADD PARTITION p_named TABLESPACE gear5;
ALTER TABLE parts MOVE PARTITION depot2 TABLESPACE ts094
NOLOGGING COMPRESS;
ALTER TABLE order_details
SPLIT PARTITION p_2009 AT (TO_DATE ('01-JUL-2009','DD-MON-YYYY'))
INTO (PARTITION p_2009h1, PARTITION p_2009h2);
ALTER TABLE four_seasons MERGE PARTITIONS quarter_one,
quarter_two INTO PARTITION quarter_two ;

45. Index Maintenance
Indexes in UNUSABLE state is one of the major issues in dealing with partitioned tables and indexes.
SELECT or DML statement that accesses index in such state will return an ORA error.
Partition maintenance operations will mark the affected local index partition and ALL global index partitions as UNUSABLE.
ALTER TABLE MOVE PARTITION
ALTER TABLE SPLIT PARTITION
ALTER TABLE TRUNCATE PARTITION
ALTER INDEX SPLIT PARTITION
SQL*Loader operations which bypass index maintenance

46. LOCAL Index SQL> SELECT PARTITION_NAME FROM USER_IND_PARTITIONS
WHERE INDEX_NAME='SALES_DATA_IND';
PARTITION_NAME
SALES_1998
SALES_1999
SALES_2000
SALES_2001
P_2009
SQL> ALTER TABLE sales_data MOVE PARTITION sales_1999 TABLESPACE users;
Table altered.
SQL> SELECT PARTITION_NAME,STATUS FROM USER_IND_PARTITIONS WHERE INDEX_NAME='SALES_DATA_IND';
PARTITION_NAME STATUS
SALES_ USABLE
SALES_ UNUSABLE
SALES_ USABLE
SALES_ USABLE
P_ USABLE
LOCAL Index

47. ALL Global Index Partitions are marked as UNUSABLE
SQL> ALTER TABLE sales_data TRUNCATE PARTITION sales_1999_h2;
Table truncated.
SQL> select partition_name,status from user_ind_partitions where index_name='PROD_ID_IND';
PARTITION_NAME STATUS
P UNUSABLE
P UNUSABLE
P_OTHERS UNUSABLE
ALL Global Index Partitions are marked as UNUSABLE
even though only one single table partition has been accessed

48. SQL> SELECT COUNT (*) FROM sales_data
WHERE time_id ='01-DEC-1999' *
ERROR at line 1:
ORA-01502: index 'SH.SALES_DATA_IND' or partition of such index is in unusable state
SQL> ALTER SESSION SET SKIP_UNUSABLE_INDEXES=TRUE;
System altered.
WHERE time_id ='01-DEC-1999‘
COUNT(*)
310

49. performed of the SALES_DATA table
SQL> EXPLAIN PLAN FOR SELECT COUNT(*) FROM sales_data
WHERE time_id ='01-DEC-1999';
Explained.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value:
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | | | (26)| 00:00:05 | | |
| 1 | SORT AGGREGATE | | | | | | | |
| 2 | PARTITION RANGE SINGLE| | | | (26)| 00:00:05 | | |
|* 3 | TABLE ACCESS FULL | SALES_DATA | | | (26)| 00:00:05 | | |
Because index partition is in an UNUSABLE state, a full table scan is being
performed of the SALES_DATA table

50. SQL> ALTER INDEX sales_data_ind REBUILD PARTITION sales_1999;
Index altered.
SQL> EXPLAIN PLAN FOR SELECT COUNT(*) FROM sales_data WHERE time_id ='01-DEC-1999';
Explained.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value:
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | | | (0)| 00:00:01 | | |
| 1 | SORT AGGREGATE | | | | | | | |
| 2 | PARTITION RANGE SINGLE| | | | (0)| 00:00:01 | | |
|* 3 | INDEX RANGE SCAN | SALES_DATA_IND | | | (0)| 00:00:01 | | |

51. Update Global Indexes
By default, many table maintenance operations on partitioned tables invalidate (mark UNUSABLE) global indexes.
We can override this default behaviour if you specify UPDATE GLOBAL INDEXES.
Partition DDL statement takes longer to execute since indexes which were previously marked UNUSABLE are updated
SQL> ALTER TABLE sales_data move partition sales_2000 tablespace example UPDATE GLOBAL INDEXES;
SQL> SELECT PARTITION_NAME,STATUS FROM USER_IND_PARTITIONS WHERE INDEX_NAME='PROD_ID_IND';
PARTITION_NAME STATUS
P USABLE
P USABLE
P_OTHERS USABLE

52. Partition Pruning Very important feature for VLDB and Data Warehouses.
CBO eliminates unneeded partitions when building a partition access list.
Operations performed only on partitions relevant to the SQL statement dramatically reduce the amount of disk reads as well as CPU time.
If using global partitioned indexes, can perform partition pruning on the index partitions by eliminating index partitions even if table partitions cannot be eliminated
Range Partitioning
range, equality and IN-list predicates
Hash Partitioning
equality and IN-list predicates

53. SQL> EXPLAIN PLAN FOR SELECT COUNT(
SQL> EXPLAIN PLAN FOR SELECT COUNT(*) FROM sales_data WHERE time_id='21-JAN-2000';
Explained.
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
PLAN_TABLE_OUTPUT
Plan hash value:
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | | | (3)| 00:00:03 | | |
| 1 | SORT AGGREGATE | | | | | | | |
| 2 | PARTITION RANGE SINGLE| | | | (3)| 00:00:03 | | |
|* 3 | TABLE ACCESS FULL | SALES_DATA | | | (3)| 00:00:03 | | |
The Pstart and Pstop columns indicate that a single partition has been accessed
by the optimizer even though the “TABLE ACCESS FULL” operation is indicated

54. Partition-wise Joins
Significantly improve the performance when joining tables with millions of rows.
Useful in VLDB and DSS environments.
Applies to Merge and Hash joins and not to Nested Loop joins.
Two tables that are equi-partitioned on the join column.
Optimizer breaks the join operation into a number of smaller joins that can be performed sequentially or in parallel.
If using parallel joins, will minimise the data exchanged by parallel slaves

55. Both tables are hash partitioned on the CUST_ID column
CREATE TABLE "SH"."SALES_DATA_HASH"
( "PROD_ID" NUMBER NOT NULL ENABLE,
"CUST_ID" NUMBER NOT NULL ENABLE,
"TIME_ID" DATE NOT NULL ENABLE,
"CHANNEL_ID" NUMBER NOT NULL ENABLE,
"PROMO_ID" NUMBER NOT NULL ENABLE,
"QUANTITY_SOLD" NUMBER(10,2) NOT NULL ENABLE,
"AMOUNT_SOLD" NUMBER(10,2) NOT NULL ENABLE )
PCTFREE 5 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS NOLOGGING
PARTITION BY HASH ("CUST_ID")
PARTITIONS 4
STORE IN (EXAMPLE, USERS) ;
CREATE TABLE SH.CUSTOMERS_HASH
(CUST_ID NUMBER,
CUST_FIRST_NAME VARCHAR2(20),
CUST_LAST_NAME VARCHAR2(40),
CUST_CITY VARCHAR2(30))
PARTITION BY HASH (CUST_ID)
Both tables are hash partitioned on the CUST_ID column

56. SQL> EXPLAIN PLAN FOR SELECT SUM (a.amount_sold),b.cust_city
FROM sales_data_hash a, customers_hash b
WHERE a.cust_id =b.cust_id
GROUP BY b.cust_city;
Explained.
PLAN_TABLE_OUTPUT
Plan hash value:
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
| 0 | SELECT STATEMENT | | 839K| 44M| (10)| 00:00:14 | | |
| 1 | HASH GROUP BY | | 839K| 44M| (10)| 00:00:14 | | |
| 2 | PARTITION HASH ALL | | 839K| 44M| (4)| 00:00:14 | | |
|* 3 | HASH JOIN | | 839K| 44M| (4)| 00:00:14 | | |
| 4 | TABLE ACCESS FULL| CUSTOMERS_HASH | | 1818K| (2)| 00:00:01 | | |
| 5 | TABLE ACCESS FULL| SALES_DATA_HASH | 839K| 20M| (3)| 00:00:13 | | |

57. Note the physical reads and consistent
Statistics
7 recursive calls
0 db block gets
4794 consistent gets
296 physical reads
0 redo size
bytes sent via SQL*Net to client
932 bytes received via SQL*Net from client
42 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
6039 consistent gets
4100 physical reads
608 rows processed
Note the physical reads and consistent
gets using the Partition wise join on Hash
Partitioned versus Non Partitioned tables

58. Using DBMS_REDEFINITION
SQL> EXEC DBMS_REDEFINITION.CAN_REDEF_TABLE('SH','SALES_NO_PART');
PL/SQL PROCEDURE SUCCESSFULLY COMPLETED.
CREATE TABLE "SH"."SALES_INTERIM"
( "PROD_ID" NUMBER NOT NULL ENABLE,
...
) PCTFREE 5 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS
TABLESPACE "EXAMPLE"
PARTITION BY RANGE ("TIME_ID")
(PARTITION SALES_1998 VALUES LESS THAN (TO_DATE('01-JAN-1999','DD-MON-YYYY')),
PARTITION SALES_2001 VALUES LESS THAN (TO_DATE('01-JAN-2002','DD-MON-YYYY')),
PARTITION P_2009 VALUES LESS THAN (MAXVALUE) );

59. DECLARE ERROR_COUNT PLS_INTEGER := 0; BEGIN DBMS_REDEFINITION
DECLARE ERROR_COUNT PLS_INTEGER := 0; BEGIN DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS('SH', 'SALES_NO_PART', 'SALES_INTERIM',1, TRUE, TRUE, TRUE, FALSE,ERROR_COUNT); DBMS_OUTPUT.PUT_LINE('ERRORS := ' || TO_CHAR(ERROR_COUNT)); END; /
SQL> EXEC DBMS_REDEFINITION.FINISH_REDEF_TABLE ('SH','SALES_NO_PART','SALES_INTERIM');
PL/SQL PROCEDURE SUCCESSFULLY COMPLETED.

60. SQL> SELECT PARTITION_NAME FROM USER_TAB_PARTITIONS WHERE TABLE_NAME='SALES_NO_PART';
PARTITION_NAME
SALES_1998
SALES_1999
SALES_2000
SALES_2001
P_2009
SQL> SELECT COUNT(*) FROM SALES_NO_PART PARTITION(SALES_1999);
COUNT(*)
247945
SQL> DROP TABLE SALES_INTERIM;
TABLE DROPPED.

61. Exchange Partition
SQL> select partition_name from user_tab_partitions where table_name='SALES_NO_PART';
PARTITION_NAME
SALES_1998
SALES_1999
SALES_2000
SQL> select count(*) from sales_2001; << NON PARTITIONED TABLE
COUNT(*)
259418
SQL> alter table sales_no_part add partition sales_2001
2 values less than ('01-JAN-2002') tablespace example;
Table altered.

62. SQL> select partition_name from user_tab_partitions where table_name='SALES_NO_PART';
SALES_1998
SALES_1999
SALES_2000
SALES_2001
SQL> ALTER TABLE sales_no_part
EXCHANGE PARTITION sales_2001
WITH TABLE sales_2001
UPDATE GLOBAL INDEXES;
Table altered.
SQL> select count(*) from sales_no_part partition(sales_2001);
COUNT(*)
259418

63. THANKS FOR ATTENDING! Gavin Soorma gavin.soorma@bankwest.com.au
Phone: