Optimization is important when working with large amounts of data. Optimization is especially important when building an app in a multi-tenant platform where you have governor limits. Join us for lessons learned while developing a finance system on Force.com. We'll cover topics like executing aggregate queries with limits and offsets, handing updates to arbitrary numbers of records, and sorting complex objects.

1. Data Design Tips for Developing
Robust Apps on Force.com
Lessons learned while developing a finance system on
Force.com
Steven Lawrance, Salesforce.com, Lead Member of the Technical Staff

2. Safe harbor
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forward-looking statements.

3. Steven Lawrance
Lead Member of the Technical Staff

4. Session Agenda
▪ Designing within limits
▪ Handing updates to arbitrary numbers of records
▪ Demonstration
▪ Executing aggregate queries with limits and offsets
▪ Sorting complex objects
▪ Q&A

5. Designing within limits
▪ Design decisions should consider resource availability
• Custom object limit
• Custom tab limit
• Storage limits
• API call limits

6. Designing within limits

7. Designing within limits
▪ Scarce
• Record storage
▪ Plentiful
• Custom objects
• Tabs
• Apex code lines
▪ Selection of limits to optimize
• Record storage limits were selected for optimization in this project.
• Runtime computation was favored over temporary storage in a custom object.

8. Designing within limits
Ne
w
Reconciliation
1
∞
Opportunity
(Donation)
∞
Primary
Campaign
1
Campaign
∞
1
Default
Designation
∞
1
∞
1
Finance Batch
Donation
Designation
∞
1
Designation

9. Handing updates to arbitrary numbers of records
@future, Maps, and Visualforce are your friends.
▪ @future method: Asynchronously update batches of records.
• Update only up to the DML execution and record limits.
▪ Maps: Identify batches in the keys and changes in the values.
• @future private static void runLater(Map<String,String> batchUpdateValues)
▪ Visualforce: Use to re-invoke the next @future method call, if needed.
• @future methods cannot be called from a @future method.

10. Handing updates to arbitrary numbers of records
Visualforce page sends groups of batches to the @future method
▪ Page checks the donation update status during the page load.
• Updates required: Call the @future method and reload the page every 4 seconds.
• Updates in progress: Reload the page every 4 seconds.
• Complete: Display the regular user interface.
▪ The @future method updates donations until it gets to the DML limits.
• Set the donation update status at the end of @future method.

11. Handing updates to arbitrary numbers of records
Processing within @future
Input from Visualforce
Key
Value
For each key,
update each donation
to the target value
Credit Card
AmEx
2013-11-02
Finance Batch
a0nK0000000FAY
8
Credit Card
AmEx
2013-11-02
Fred Smith
AmEx
2013-11-02
$5.00
Finance Batch
a0nK0000000FAY8
Alex Jones
AmEx
2013-11-02
$10.00
Finance Batch
a0nK0000000FAY8
Check
2013-11-02
B123456
.
.
.
Finance Batch
a0nK0000000FAY
9
.
.
.
.
.
.
Catherine Katz
AmEx
2013-11-02
$10.00
.
.
.

12. Demonstration

13. Executing aggregate queries with limits and offsets
▪ Aggregations can return at most 500 rows per query.
▪ By using LIMIT and OFFSET, it’s possible to query more than 500
aggregated rows.
▪ In an aggregate query, the OFFSET can’t be 2000 or higher.

14. Executing aggregate queries with limits and offsets
for (Integer batchOffset = 0; batchOffset < 2000;) {
Integer aggregateBatchCount = 0, aggregateBatchSize = 500;
for (AggregateResult donationBatch : [SELECT … FROM … WHERE …
GROUP BY … ORDER BY … NULLS FIRST
LIMIT :aggregateBatchSize OFFSET :batchOffset]) {
aggregateBatchCount++;
…
}
if (aggregateBatchCount < aggregateBatchSize) { break; }
else { batchOffset += aggregateBatchCount; }
}

15. Executing aggregate queries with limits and offsets
Break apart disjunctions into separate queries if it’s faster.
▪ If your query takes too long to execute and makes use of ‘OR’, then try
splitting it into multiple queries that don’t use ‘OR’
SELECT … FROM Donation_Designation__c
WHERE Donation__r.CloseDate >= :startDate
AND Donation__r.CloseDate < :endDatePlusOne
AND (Donation__r.Fin_Batch__r.Rec__c = :recId
OR Donation__r.Batch__c = NULL
OR Donation__r.Batch__r.Status__c = 'Committed')
GROUP BY …
ORDER BY …
LIMIT … OFFSET …

16. Executing aggregate queries with limits and offsets
▪ The query plan in the underlying database is much more efficient when
all filters are conjunctive (joined with ‘AND’).
SELECT … FROM Donation_Designation__c
WHERE Donation__r.CloseDate >= :startDate
AND Donation__r.CloseDate < :endDatePlusOne
AND Donation__r.Fin_Batch__r.Rec__c = :recId
GROUP BY …
ORDER BY …
LIMIT … OFFSET …

17. Executing aggregate queries with limits and offsets
▪ Index range scans are faster than table scans.
▪ Use of ‘OR’ can lead to table scans.
▪ Salesforce.com can create an index for frequently filtered fields.

18. Sorting complex objects
▪ Before Winter ‘14, using a Map<String,ComplexObject> and a
List<String> to call List.sort() was a way to sort without running out of
script statements. The properties exist in the String key in the order to
sort by.
▪ In Winter ’14 and beyond, the recommended approach is to implement
the Comparable interface and call List.sort() on a List of your object.
• public class ComplexObject implements Comparable {
…
public Integer compareTo(Object compareTo) { /* implementation here */ }
}

19. Steven Lawrance
Lead Member of the
Technical Staff