1. DB Tuning
Ch 14. Parallel Processing Ch 15. Performance of DML Ch 16. Analytic Function
Jaeseok Myung
Intelligent Database Systems Lab
School of Computer Science & Engineering
Seoul National University, Seoul, Korea
Center for E-Business Technology
Seoul National University
Seoul, Korea

2. Parallel Processing Goal Architecture Utilization of System Resource
Reduction of Response Time
Multi-Processes
Response Time = CPU Time + Wait Time
Architecture
Query Coordinator
Syntactic Analyzing
Assign small jobs to slaves
Generate final result
Slave Process
Do works
Send results

3. How to PP Parameters in Oracle Two ways of using PP functionality
Parallel_min_server
Determine initial minimum, Default : 0
Parallel_max_server
Determine initial maximum, Default : 5, Max : 255
Two ways of using PP functionality
Insert a hint into a query
SELECT /*+ PARALLEL(A, 2) */ user, sum(amount) FROM sales_history GROUP BY user;
Alter the degree of table
ALTER TABLE sales_history PARALLEL 2;

4. Execution Plans of PP

5. Execution Plans of PP
Parallel_from_serial, Parallel_to_serial, Parallel_to_parallel
Parallel_combined_with_parent, Parallel_combined_with_child

6. DB Tuning
Ch 14. Parallel Processing Ch 15. Performance of DML Ch 16. Analytic Function
Jaeseok Myung
Intelligent Database Systems Lab
School of Computer Science & Engineering
Seoul National University, Seoul, Korea
Center for E-Business Technology
Seoul National University
Seoul, Korea

7. Issues on DML Processing
Excessive Requests for Resources
Rollback Segment
Redo Log
Disk IO
Excessive Indices
Overhead for index management
A Misguided Execution Plan
We can put ‘where clause’ into the DML

8. Insert (1) Conventional Insert
INSERT INTO TAB1 VALUES (COL1, COL2);
Index, Disk IO Tunings can be applied
A special ‘insert’ including ‘select’ has more options
INSERT INTO TAB1 SELECT COL1, COL2 FROM TAB2 WHERE COL3 > 100;
Direct Loading
Parallel Direct Loading
Nologging

9. Direct Loading
INSERT INTO TAB1 ~;
INSERT INTO /*+ APPEND */ TAB1 ~;

10. Insert (2) Parallel Direct Loading Nologging
Direct Loading + Parallel Functionality
ALTER SESSION ENABLE PARALLEL DML;
INSERT /*+ PARALLEL (A, 4) */ INTO TAB1
Nologging
Only be allowed with Direct Loading or Parallel Direct Loading
ALTER TABLE TAB1 NOLOGGING;
We may need backup

11. Delete & Update (1) Resources
Need more rollback segment than insert operation
More RedoLog, More Disk IO

12. Delete & Update (2) Checkpoint Parallel Hint Alternatives Index Counts
Execution Plan – Where Clause
Parallel Hint
DELETE /*+ PARALLEL (A, 4) */ ~;
UPDATE /*+ PARALLEL (A, 4) */ ~;
Alternatives
Use ‘Insert’ instead of ‘Delete’ if we have too much data
Less RedoLog, Less Rollback Segment

13. DB Tuning
Ch 14. Parallel Processing Ch 15. Performance of DML Ch 16. Analytic Function
Jaeseok Myung
Intelligent Database Systems Lab
School of Computer Science & Engineering
Seoul National University, Seoul, Korea
Center for E-Business Technology
Seoul National University
Seoul, Korea

14. Analytic Function Keep SQL queries to be simple
Use less GROUP BY
SELECT deptno, name, sal, COUNT(sal) OVER (PARTITION BY deptno ORDER BY sal) FROM employee;
AVG, COUNT, MIN, MAX, …
Tune indices carefully

15. Conclusion How much helpful? – It’s not a critical section
Ch 14. Parallel Processing
Ch 15. Performance of DML
Ch 16. Analytic Function
But, Interesting
Thank you