Stored procedures often get a bad rap, but this webinar argues that many of the things people hate about stored procedures are more about the implementation, rather than the concept. Watch this webinar presented by John Hugg, Founding Engineer, VoltDB to understand how stored procedure “superpowers” can make your application faster, simpler and safer.

1. Stored Procedure Superpowers
A guide for anyone writing (or considering writing) VoltDB stored procedures
May 19th, 2016 / John Hugg / @johnhugg

2. Who Am I?
• First developer on the VoltDB project.
• Previously at Vertica and other data
startups.
• Have made so many bad decisions
over the years, that now I almost know
what I'm talking about.
• jhugg@voltdb.com
• @johnhugg
• http://chat.voltdb.com

3. Today’s Talk
1. Why do people hate stored procedures?
2. It doesn’t matter; you’re going to use them; here’s why.
Subtitle: “Stored Procedures are Awesome!”
3. Given that…
What has VoltDB done to make you hate stored procedures less?
Subtitle: “Practical Stuff!”

4. Not Today’s Talk
All of the VoltDB stuff we cover in other talks, documentation,
examples, tutorials, Volt University, etc…
This includes:
• How to partition schema and operations (docs, VoltU, examples)
• Why procedures should be deterministic (docs, talks)
• How to use general VoltDB features (docs, examples)

5. Why Do People
Hate Stored
Procedures?

6. Stored procedure languages are one-offs
Can’t be debugged in an IDE
Error messages are often unhelpful
Parameters are inflexible
Stored procedures hide business logic
Stored procedures separate logic into two pieces
http://blog.codinghorror.com/who-needs-stored-procedures-anyways/
WhytheHate?

7. We’re going to
use stored
procedures
anyway.

9. A Relevant Comparison
Remote Local
10 million packets per second
(10GigE)
500 gigaflops
(one CPU)
500,000 ns
to fetch across a network
80 ns
to fetch from main memory

10. 3-Prong Efficiency Argument
For OLTP workloads, stored procedures mean:
• More throughput and less latency for the same cost
• More complexity and power for the same cost
• Stronger consistency (CAP & ACID) for the same cost
All of the Above

11. Boring Math Latency Argument
• Latency is not uniform.
Let’s say 1 of 20 messages takes > 5ms to deliver.
Let’s say 19 of 20 take < 1ms.
• If transaction A requires 1 network round trip, 95% of responses will
be under 1ms.
• If transaction B requires 5 network round trips, 75% of responses will
be under 5ms.

12. Boring Math Latency Argument 2
• When you replace 10 RTs with 1 RT, your 99% latency percentile
becomes your 99.9% latency percentile (by math).

13. More boring latency. Ugh.
Stored Proc Client-Side Txn Logic
t0: Grab a Lock 1 µs 1 µs
t1: Send data to logic 250 µs
t2: Do Biz Logic 10 µs 10 µs
t3: Respond over network 250 µs
t4: Make Updates 10 µs 10 µs
t5: Release Lock 1 µs 1 µs
Total 22 µs 522 µs

14. More boring latency. Ugh.
Stored Proc Client-Side Txn Logic
t0: Grab a Lock 1 µs 1 µs
t1: Send data to logic 250 µs
t2: Do Biz Logic 10 µs 10 µs
t3: Respond over network 250 µs
t4: Make Updates 10 µs 10 µs
t5: Release Lock 1 µs 1 µs
Total 22 µs 522 µs
Holding a lock for 24x longer
means more contention.
More contention
means even more latency.

15. Stored Procedure Performance
• Moving data is harder than
moving logic
• No lock holding during a
network round trip
• Logical representation is
smaller on the wire or disk

16. Stored procedure languages are one-offs
Can’t be debugged in an IDE
Error messages are often unhelpful
Parameters are inflexible
Stored procedures hide business logic
Stored procedures separate logic into two pieces
http://blog.codinghorror.com/who-needs-stored-procedures-anyways/
WhytheHate?

17. Stored procedure languages are one-offs
Can’t be debugged in an IDE
Error messages are often unhelpful
Parameters are inflexible
Stored procedures hide business logic
Stored procedures separate logic into two pieces
http://blog.codinghorror.com/who-needs-stored-procedures-anyways/
WhytheHate?
ImplementationLegit

18. Procedure API
Microservices, Microservices, Microservices
Your App’s
State
Schema
Constraint
User
ConstraintClient
Application
Procs let you enforce more powerful constraints
Unique
Foreign Key
Triggers
No customer has more than 6 open orders.
Only one employee at each company has no boss.
No print job requires more than 10ml of ink.

19. Use Different Clients With Shared Logic
Procedure API
Your App’s
State
Client
Application
Java
Client
Application
C++
Client
Application
Node.js
ReserveSeat
ReserveSeat
ReserveSeat

20. Change Logic Centrally
Procedure API
Contains ReserveSeat
1.0 logic
Your App’s
State
Client
Application
Java
Client
Application
C++
Client
Application
Node.js
ReserveSeat
ReserveSeat
ReserveSeat

21. Change Logic Centrally
Procedure API
Contains ReserveSeat
1.0 logic
Your App’s
State
Client
Application
Java
Client
Application
C++
Client
Application
Node.js
ReserveSeat
ReserveSeat
ReserveSeat
Procedure API
Contains ReserveSeat
2.0 logic

22. Change Logic Centrally
Your App’s
State
Client
Application
Java
Client
Application
C++
Client
Application
Node.js
ReserveSeat
ReserveSeat
ReserveSeat Procedure API
Contains ReserveSeat
2.0 logic

23. So…
100% Stored
Procedures Then?

24. Why you might not care…

25. Slower Apps
• I run the VoltDB forums on MySQL.
• Peak traffic is about 1 TPS in actual writes.
• It runs on the smallest Linode instance and is mostly idle.
• Optimizing this is pretty dumb.
• This example is clear, but where is the line?

26. Analytics
• How many purple hats were sold on Tuesdays in March when it was
raining?
• I can answer that with a SQL query. A stored proc won’t buy me
much.

27. Performance Benefit of Stored Procedures
KV CRUD Complex Transactional Logic

28. Do it when it pays off
• If you don’t have transactional logic, the argument for stored
procedures becomes much less strong.
• You’re down to saving round trips — though that can be a big
difference for high performance apps.

29. Optimization Rules Apply
Operation 1 Operation 2
Takes 100ms instead of 1ms Takes 3ms instead of 1ms
Runs once per second Runs 25k times per second
Optimization saves 10% of one CPU Optimization saves 50 CPUs

30. Stored procedure languages are one-offs
Can’t be debugged in an IDE
Error messages are often unhelpful
Parameters are inflexible
Stored procedures hide business logic
Stored procedures separate logic into two pieces
http://blog.codinghorror.com/who-needs-stored-procedures-anyways/
WhytheHate?
ImplementationLegit

31. One-OffLanguages?

32. Use Java
One-OffLanguages?

33. Why Java
• Familiarity and Popularity
• IDEs
• Safety
• Performance
• Code as Data / Hot Swap Code
• Other JVM Languages
Alternatives:
Lua / Javascript

34. Example

35. Understanding the API

37. RevisionControl

38. Can’tDebuginIDE

39. Example
in
Eclipse
Can’tDebuginIDE

40. UnhelpfulErrors

41. Stack
Traces!
Custom
Errors
UnhelpfulErrors

42. InflexibleParameters

43. Many Types
Arrays
JSON
Blobs
Compression
Avro/Protobufs/etc
InflexibleParameters

44. Examples!

45. https://github.com/VoltDB/app-debug-and-test
W
IP

46. InProcessVoltDBServer API
• InProcessVoltDBServer configPartitionCount(int partitionCount);
• InProcessVoltDBServer configPathToLicense(String path);
• InProcessVoltDBServer start();
• InProcessVoltDBServer runDDLFromPath(String path);
• InProcessVoltDBServer runDDLFromString(String ddl);
• Client getClient();
• void loadRow(String tableName, Object... row);
• void shutdown();

47. Close Slides Now John.

48. More?

49. Partitioning
Async Clients
Understanding
SQL Plans
Using Indexes Well
http://docs.voltdb.com

50. http://university.voltdb.com

51. https://github.com/VoltDB/voltdb/tree/master/examples

52. Conclusion & Thanks
• Stored procs get a
mostly undeserved
bad rap
• To go fast, they make
tons of sense
• There are advantages
besides speed
jhugg@voltdb.com / @johnhugg / chat.voltdb.com