1. Apex Algorithms: Tips & Tricks
Mary Scotton
Developer Evangelist
salesforce.com
@rockchick322004
Gonzalo Abruna
Developer & Analyst
4C Consulting (Belgium)
@GonzaloAbruna

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3. Agenda
• Top Coder Challenge
• Optimize SOQL queries
• How to optimize an algorithm: tips & tricks
• Summary
• References
• Q&A

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Gonzalo Abruna
Developer & Analyst, 4C Consulting (Belgium)

9. Optimize SOQL queries
SOQL Limits
• 100 SOQL queries per transaction (200 if transaction is asynchronous)
• 50.000 rows retrieved by SOQL queries
• 120 seconds maximum SOQL query run time

10. Optimize SOQL queries
Data Model

11. Optimize SOQL queries
Requirements: Sample Scenario
• Query all the Contacts that have worked for an Account, via join object
• For those Contacts, get all the Accounts they have worked for

12. Optimize SOQL queries
Solution #1
• Upsides
– Easy to implement
• Downsides
– Many loops
– Many SOQLs
– Bad performance

13. Optimize SOQL queries
Solution #2
• Upsides
– Less SOQL queries
– Less loops (important for complex algorithms)
• Downsides
– Not much better than Solution #1
– SOQL Limit: “In a SOQL query with parent-child relationship sub-queries, each parent-child
relationship counts as an additional query. These types of queries have a limit of three times the
number for top-level queries. The row counts from these relationship queries contribute to the row
counts of the overall code execution. In addition to static SOQL statements, calls to the following
methods count against the number of SOQL statements issued in a request.”

14. Optimize SOQL queries
Solution #3
• Upsides
– The most efficient
– Less SOQL queries
– Less loops (important for complex algorithms)
• Downsides
– Data structures may be required to represent the data

15. Representing the Data
• Upsides
– Avoids unnecessary loops
– Direct access to the records
– Easier to handle than lists without key
• Downsides
– Be careful with null pointer exceptions and reference to null object
– Maps are not ordered
Solution #3, Part 2: Using Map<Id, List<sObject>>

16. How to Optimize an Algorithm
• Use Map<Id, sObject> in SOQL queries
List<Account> listAccounts = [SELECT Id, Name FROM Account];
Map<Id, Account> mapAccounts = new Map<Id, Account>([SELECT Id, Name FROM
Account]);
• Estimate how big your data is & test empty values scenario
• Avoid unnecessary loops: try to reuse loops without losing readability of code
Top Tricks

17. How to Optimize an Algorithm
• Put conditions in SOQL queries, not in if statements
List<Account> listAccounts = [SELECT Id, Name, Type FROM Account];
for(Account acc : listAccounts){
if(acc.Type == ‘Prospect’){…}
}
VS
List<Account> listAccounts = [SELECT Id, Name, Type FROM Account WHERE Type = ‘Prospect’];
Top Tricks

18. How to Optimize an Algorithm
• Query only the fields that you need
• Try to avoid putting formula fields on a WHERE clause
• Parent-Child SOQL to avoid loops
– Example: get the three newest Contacts per Account
Top Tricks

19. Summary
• Every algorithm is different
• Think before coding
• Be aware of limits
• Readability of code is important
• Complex algorithms can be broken down into smaller and easier (divide & conquer)
• The place of an algorithm is critical

20. References
• Developer blogs https://developer.salesforce.com/blogs/
• Force.com Apex developer guide.
http://www.salesforce.com/us/developer/docs/apexcode/
salesforce_apex_language_reference.pdf
• Appelman, Dan. Advanced Apex Programming. http://advancedapex.com
• Douglas, Jeff. Blog. http://blog.jeffdouglas.com
• Altman, Jesse. Blog. http://jessealtman.com
• Bob Buzzard Blog. http://bobbuzzard.blogspot.be
• Carlberg, Reid. Blog. http://reidcarlberg.com

21. Mary Scotton
Developer Evangelist
salesforce.com
@rockchick322004
Gonzalo Abruna
Developer & Analyst
4C Consulting (Belgium)
@GonzaloAbruna