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Partitioning – Lets Divide and Conquer ! Gavin Soorma, Senior Oracle DBA, Bankwest.

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Presentation on theme: "Partitioning – Lets Divide and Conquer ! Gavin Soorma, Senior Oracle DBA, Bankwest."— Presentation transcript:

1 Partitioning – Lets Divide and Conquer ! Gavin Soorma, Senior Oracle DBA, Bankwest

2 Agenda The what, who and why of Partitioning Partitioning – decisions and challenges Partitioning – Its evolution Types of Partitioning Whats 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 Really Big Table Really Big Table Partitioning stores a data segment (Table, Index, LOB) as multiple segments while retaining a logically massive structure. 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 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 ReleaseCore Functionality Oracle 8.0 (1997)Range Partitioning Oracle 8iHash and Composite Partitioning Oracle 9iList Partitioning Oracle 9i Release 2Composite Range-List Partitioning Oracle 10gGlobal Hash Indexes Oracle 10g Release 21M partitions per table Oracle 11gInterval 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 Range Partitioning 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 Method 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 ); CREATE TABLE employees ( empno NUMBER(4), ename VARCHAR2(30), sal NUMBER ) 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 Table LINEITEMS RANGE (order_date) PRIMARY KEY (order_id) RANGE (order_date) FOREIGN KEY (order_id) Redundant storage of order_date Jan 2009Feb 2009 Jan 2009Feb 2009 Dec 2009

24 11g REF Partitioning … … … … Table ORDERS Table LINEITEMS RANGE (order_date) PRIMARY KEY (order_id) RANGE (order_date) FOREIGN KEY (order_id) Partition By Reference Partitioning Key in Child Table Inherited through PK-FK relationship Jan 2009Feb 2009 Jan 2009Feb 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 RangeListHash Range11g9i8i List11g Range/Range Order Date, Shipping Date List/Range Salesman, Date of Sale List/List State, County Data is partitioned along two dimesions Introduced in Oracle 8i with Range/Hash 9i extended to Range/List 11g extended to all combinations

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

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

32 Partitioning StrategyData DistributionSample Business Usage Range PartitioningBased on consecutive ranges of values Orders table range partitioned by order_date List PartitioningBased on unordered lists of values. Orders table list partitioned by country Hash PartitioningBased 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 partitioned by order_date and sub-partitioned by hash on customer_id Orders table is range partitioned by order_date and sub-partitioned by range on shipment_date 10g Partitioning - Summary

33 11g Partitioning - Summary Partitioning ExtensionPartitioning KeySample 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 PartitioningPartitioning 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'; PARTITION_NAME 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) LOCAL 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_P102 EXAMPLE SYS_P103 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 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 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)); Table Partitioned on order_date

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 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_1998 USABLE SALES_1999 UNUSABLE SALES_2000 USABLE SALES_2001 USABLE P_2009 USABLE LOCAL Index

47 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 P1 UNUSABLE P2 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. SQL> SELECT COUNT (*) FROM sales_data WHERE time_id ='01-DEC-1999 COUNT(*)

49 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 | | 1 | 9 | 342 (26)| 00:00:05 | | | | 1 | SORT AGGREGATE | | 1 | 9 | | | | | | 2 | PARTITION RANGE SINGLE| | 276 | 2484 | 342 (26)| 00:00:05 | 2 | 2 | |* 3 | TABLE ACCESS FULL | SALES_DATA | 276 | 2484 | 342 (26)| 00:00:05 | 2 | 2 | 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 | | 1 | 9 | 5 (0)| 00:00:01 | | | | 1 | SORT AGGREGATE | | 1 | 9 | | | | | | 2 | PARTITION RANGE SINGLE| | 310 | 2790 | 5 (0)| 00:00:01 | 2 | 2 | |* 3 | INDEX RANGE SCAN | SALES_DATA_IND | 310 | 2790 | 5 (0)| 00:00:01 | 2 | 2 |

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 P1 USABLE P2 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(*) 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 | | 1 | 8 | 246 (3)| 00:00:03 | | | | 1 | SORT AGGREGATE | | 1 | 8 | | | | | | 2 | PARTITION RANGE SINGLE| | 468 | 3744 | 246 (3)| 00:00:03 | 5 | 5 | |* 3 | TABLE ACCESS FULL | SALES_DATA | 468 | 3744 | 246 (3)| 00:00:03 | 5 | 5 | 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 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) PARTITIONS 4 STORE IN (EXAMPLE, USERS) ; 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| 1158 (10)| 00:00:14 | | | | 1 | HASH GROUP BY | | 839K| 44M| 1158 (10)| 00:00:14 | | | | 2 | PARTITION HASH ALL | | 839K| 44M| 1085 (4)| 00:00:14 | 1 | 4 | |* 3 | HASH JOIN | | 839K| 44M| 1085 (4)| 00:00:14 | | | | 4 | TABLE ACCESS FULL| CUSTOMERS_HASH | | 1818K| 61 (2)| 00:00:01 | 1 | 4 | | 5 | TABLE ACCESS FULL| SALES_DATA_HASH | 839K| 20M| 1012 (3)| 00:00:13 | 1 | 4 |

57 Statistics 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) Statistics recursive calls 0 db block gets 6039 consistent gets 4100 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) 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.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(*) 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(*) SQL> alter table sales_no_part add partition sales_ 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'; PARTITION_NAME 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(*)

63 THANKS FOR ATTENDING! Gavin Soorma Phone:


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