1. Understanding Indexes in KB_SQL March 2001
Just-in-Time Indexes
March 2001
Understanding Indexes in KB_SQL
March 2001

2. Learning Objectives
What options do I have to improve query performance?
The answer is…indexes.
Review indexing strategies
Introduce just-in-time indexes
Discuss advantages and caveats

3. Improve Performance
Why does my query run so slow?

4. Query Results

5. Show Plan/Stats: Query
Run query with Show Plan and Show Stats

6. Show Plan: Results
Note: No index being used

7. Show Stats: Results
Note: Selecting 9 of rows searched

8. Show All Plans: Query
Run query with SHOW_ALL_PLANS to see if index is available

9. Show All Plans: Results
Note: No indexes available

10. Index Exists

11. Define Index to KB_SQL
Add BY_NAME index in KB_SQL

12. New Show Plan
Note: BY_NAME index is used, cost is reduced

13. New Show Stats
Note: Selecting 9 of 9 rows searched

14. New Show All Plans
Note: BY_NAME index available

15. How do we improve performance if we don’t have sufficient indexes?
What are the options?
Create supplemental table(s)
Build index
Create just-in-time index
When will it be populated?
How often should it be updated?
Advantages and caveats?

16. Create Supplemental Tables
Create new table
Join to “base” table

17. Build the Index Benefits Caveats
Queries only look at key data which results in faster searches
Caveats
Time
Resources
Additional globals to maintain

18. What if there is no index?

19. What if there is no index? (cont)

20. What if there is no index? (cont)

21. Just-in-Time Indexes When will the index be populated?
How often should the index be updated?

22. Just-in-Time Indexes: Advantages and Caveats
Advantages over traditional indexes
Add only the indexes that the user demands
Reduce wasted effort to build indexes that won’t be used
Caveats
Does not provide up-to-the-minute data accuracy
2 or more queries to realize benefit

23. Build the Just-in-Time Index

24. Define the Index to KB_SQL

25. New Show All Plans
Note: Two indexes available; BY_SUPPLIER is accepted based on constraint

26. New Show Plan
Note: BY_SUPPLIER index is used

27. New Show Stats
Note: Selecting 4 of 4 rows searched

28. Summary Discussed options available to help improve query performance
The answer is…indexes.
Reviewed indexing strategies
Introduced just-in-time indexes
Discussed advantages and caveats