Top 10 DB2 SupportTop 10 DB2 SupportTop 10 DB2 SupportTop 10 DB2 Support
Nightmares & How toNightmares & How toNightmares ...
Part 2 – Are your tools up to the job?
Image of a junior DBA
Long elapsed times for BI queries (over 30 mins!)
were causin...
They tried…….
Increasingtemp space
Checking their BI tool
Running DB2 Index Advisor
Creating additional indexes IIIIIII II...
So Triton stepped in…..
We used one of our favourite analysis tools:
Brother Eagle®
From DBI Software
…and we discovered
A
B
C
1
2
3
4
A 1
A 2
A 3
A 4
B 1
B 2
B 3
B 4
C 1
C 2
C 3
C 4
Join
A VERY high query execution cost
SQL...
The Solution
We reworked the BI report definitions to add missing
database relationships
The BI tool then generated correc...
The Moral of the Story
Many applications (such as BI, ERP and Java
frameworks) are generating their own SQL – it can be
di...
www.triton.co.uk
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Top 10 DB2 Support Nightmares #2

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The second instalment in our DB2 Support Nightmares series. Download if you dare!
www.triton.co.uk

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Top 10 DB2 Support Nightmares #2

  1. 1. Top 10 DB2 SupportTop 10 DB2 SupportTop 10 DB2 SupportTop 10 DB2 Support Nightmares & How toNightmares & How toNightmares & How toNightmares & How to Avoid ThemAvoid ThemAvoid ThemAvoid Them #2#2#2#2
  2. 2. Part 2 – Are your tools up to the job? Image of a junior DBA Long elapsed times for BI queries (over 30 mins!) were causing one of our customers some serious headaches
  3. 3. They tried……. Increasingtemp space Checking their BI tool Running DB2 Index Advisor Creating additional indexes IIIIIII IIIIIII IIIIIII IIIIIII
  4. 4. So Triton stepped in….. We used one of our favourite analysis tools: Brother Eagle® From DBI Software
  5. 5. …and we discovered A B C 1 2 3 4 A 1 A 2 A 3 A 4 B 1 B 2 B 3 B 4 C 1 C 2 C 3 C 4 Join A VERY high query execution cost SQL being generated by the BI tool was captured and found to be a Cartesian join of two tables Each with more than 25M rows! New indexes were not being used
  6. 6. The Solution We reworked the BI report definitions to add missing database relationships The BI tool then generated correct JOIN predicates The reports were re-run to successful completion in under 2 minutes!
  7. 7. The Moral of the Story Many applications (such as BI, ERP and Java frameworks) are generating their own SQL – it can be difficult to know exactly what’s getting thrown at DB2. Correct tooling (and the skills to interpret them!) is essential.
  8. 8. www.triton.co.uk

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