Performance Tuning for Visualforce and Apex

Performance Tuning for Visualforce
and Apex
Stuart Bernstein
ISV Technical Evangelist
Thomas Harris
LMTS, CCE Production Support
John Tan
SMTS, CCE Technical Enablement

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Stuart Bernstein
ISV Technical Evangelist
Thomas Harris
LMTS, CCE Production Support
John Tan
SMTS, CCE Technical Enablement

Introduction

This session is designed to help with common Visualforce/Apex
performance issues targeted towards intermediate/advanced
Force.com developers.

Agenda

 SOQL/SOSL
 Batch Apex
 Record Lock Contention
 Visualforce
 Debugging Tools
 Q&A

You Need to Build ON A Solid Foundation

 Follow SOQL Best practices
 Then tune Apex
 Then tune Visualforce

Indexes Are Vital for Well-performing SOQL

 Without an index the SOQL query may not perform well
 Standard indexes already exist on Record_Type_Id, Division,
Created_Date, System_Modstamp (Last_Modified_Date),
Name, Email (for Contacts and Leads), and the unique
Salesforce record ID (Foreign Keys)

Administrators Can Create a Custom Index

Need Additional Indexes?
 Salesforce support can create single and two-column custom indexes
on most fields (with the exception of multi-picklists, formula fields that
reference other objects, and Long Text Area/Rich Text Area)
 Open a case
- Sample Query
- Bind Variables
- Org ID and user ID who would run the query
- Suggested index - OPTIONAL
 If they create an index, then SAVE and document where the index
was created

Will an Index Be Used?

• Whether an index is used is based on the expected number of
records that will be returned.
• A standard index will generally be used:
• If the filter matches less than 30% of the total records, up to 1M records.
• A custom index will generally be used:
• If the filter matches less than 10% of the total records, up to 333K
records.
• OR conditions require that all columns be indexed

Use a Standard Index

Select name from account where Id=‘00530000003hQLJ’

Performs quickly because ID is an standard index

Use a Custom Index

Select name from account where
SLA_Serial_Number__c=‘1234567’

Performs quickly because SLA_Serial_Number__c is a custom
index

Use a Custom Index

Select name from account where SLA_Serial_Number__c=‘’

Doesn’t work because null prevents the index from being used.

Use a Custom Index

Select name from account where SLA_Serial_Number__c IN
:ListOfSerialNums

May work well
if no null variable in ListOfSerialNums
filter matches less than 10% of the total records up to 333,000 records
30% of the total records up to one million records if this was a standard index
(it’s not)

Don’t Use NOT IN

Select name from account where SLA_Status__C NOT IN (‘Valid’)

NOT IN also prevents the index from being used

One (best) Index Will Be Used

Select name from account where SLA_Status__C NOT IN
(‘Processed’) AND SLA_Serial_Number__c=‘1234567’

If one index is not usable, then the best remaining index will be
used.

One (best) Index Will Be Used

Select name from account where SLA_Status__C IN
(‘Processed’) AND SLA_Serial_Number__c=‘1234567’

If all indexes are usable, the best index will be used.

Cross-object Formula Fields Can Prevent Index
Usage
Contact.SLA_Formula__c is a formula field that copies the value
in Account.SLA_Serial_Number__c.
 Select name from contact where SLA_Formula__c IN
:ListOfSerialNums
 A custom index on Account.SLA_Serial_Number__c cannot be used
in this query.
Use this query instead, where the index can be used:
 Select name from contact where Account.SLA_Serial_Number__c IN
:ListOfSerialNums

Denormalizing Data Increases Performance

Select name from contact where Account.SLA_Serial_Number__c
IN :ListOfSerialNums

Solution
Copy SLA_Serial_Number to a field in Contact (don’t use a
formula) and make the field an External Id
OR query for the account IDs with the SLA Serial number first

Query Only The Necessary Fields
SELECT
AccountNumber,AccountSource,Active__c,AnnualRevenue,BillingCity,BillingCountry,BillingPo
stalCode,BillingState,BillingStreet,CreatedById,CreatedDate,CustomerPriority__c,Description,
Fax,Id,Industry,IsDeleted,Jigsaw,JigsawCompanyId,LastActivityDate,LastModifiedById,LastM
odifiedDate,MasterRecordId,Name,NumberOfEmployees,NumberofLocations__c,OwnerId,O
wnership,ParentId,Phone,Rating,ShippingCity,ShippingCountry,ShippingPostalCode,Shipping
State,ShippingStreet,Sic,SicDesc,Site,SLAExpirationDate__c,SLA_Serial_Number__c,SLA__
c,SystemModstamp,TickerSymbol,Type,UpsellOpportunity__c,Website FROM Account

SOSL Performance Best Practices

 SOSL queries for the data using a different technique but then
takes the data and adds the where clause using SOQL
- Eg FIND {foo} RETURNING Account (Id WHERE City='Rome') is
analogous to SELECT Id FROM Account WHERE ID IN (<list of Ids
from search>) AND City='Rome’
 Follow SOQL best practices for the where clause

Batch Apex

 Most common issue is performance of SOQL used in the start()
method.
 Avoid the use of non-selective filters in the start() method.
- Queries will perform significantly worse as more data is added.

 Don’t add a non-selective filter to filter out a few rows relative to
the overall size of the result set. Instead, use Apex to filter out
rows in the execute() method.

Batch Apex – Start Method Queries

 Suppose you have 5M records in Account. You want to process the
80% of those records represented by this query:
- SELECT Id FROM Account WHERE Rating__c IN ('Excellent','Good','Moderate')

 Since there is no way to use a selective filter in a query for these
records, this query will not run quickly even if Rating__c is indexed.
 As an alternative, use this query in the start method:
- SELECT Id FROM Account

 Filter out the unwanted records in the execute method.

Batch Apex – Start Method Queries – Sample Class
global Database.QueryLocator<SObject> start(Database.BatchableContext bc) {
return Database.getQueryLocator('SELECT Id FROM Account');
}

global void execute(Database.BatchableContext bc, List<Account> scope) {
List<Account> actualScope = [SELECT Id, Name, Description FROM Account
WHERE Rating__c IN
('Excellent','Good','Moderate’)
AND Id IN :scope];
for(Account acc : actualScope) { /* do something */ }
}

Batch Apex – Avoid Errors in Bulk DML
global void execute(Database.BatchableContext bc, List<Account>
scope) {
for(Account acc : scope) { /* do something */ }
Database.SaveResult[] results = Database.update(scope,
false);
/* look at results */
}

 If an error occurs in this save operation, Salesforce will try to save it one
record at a time.
 This performs significantly slower than a bulk save without errors.

Parent-Child Locking
 Insert of Contact requires locking the parent Account.
 Insert or Update of Event requires locking both the parent Contact and the
parent Account.
 Insert or Update of Task requires locking both the parent Contact and
parent Account, if the Task is marked as complete.
 Insert of Case requires locking the parent Contact and parent Account.
 In objects that are part of a master/detail relationship, updating a detail
record requires locking the parent if roll-up summary fields exist.

Sharing Calculations

 “Implicit” Sharing
- Record access built into Salesforce applications
 Parent Implicit Sharing (Account only, private sharing model)
- Access to Contact/Opportunity/Case = Read access to parent
account
- not used when sharing on the child is controlled by parent
- when user loses access to a child, need to check all other children
to see if we can delete the parent implicit share

Should we delete Jane’s parent implicit share?
 Sharing calculations Universal
Containers
impacted by Data Skew
 300K unassigned contacts X
under account
 Private sharing model ?
 Jane has access to contact
Bob Smith
Bob
Smith
Fred
Green
Betty
Brown … 300K
Contact

 Jane losses access to contact
 Should we delete Jane’s
parent implicit share for X
Universal Containers?
 Can’t code around Data Skew

Effects of data skew

 Sharing calculations run longer
 Concurrent Request Limit error
- Synchronous Apex request starts counting against the limit waiting >
5 sec for lock.
 UNABLE_TO_LOCK_ROW error
- Timed out waiting 10 seconds to acquire lock.
- Even if no errors occur, waiting for locks can significantly slow DML
operations.

Recommendations

 Consider a public read/write sharing model
- Parent will still be locked. No sharing calculations.
 10K children or less
 Prevent parent-child data skews
- Detect whether existing accounts already have "reached their limit"
of child records, and create new accounts.

Visualforce – Best Practices

 http://developer.force.com/dreamforce/11/session/Blazing-
Fast-Visualforce-Pages
 View State
- Filter and Paginate
- Transient keyword
- Simplify component hierarchy
- JavaScript Remoting

Analyzing Performance

 Measure performance in the browser first to see if the
problem is client-side or server-side.
- Chrome Developer Tools and the Firebug plugin for Firefox will both
work for this.
 After confirming the problem is on the server, use the
Salesforce Developer Console to find areas you can tune.

Example Visualforce Page: DebugPage

 In Chrome, press F12 to open Developer Tools.
 Use the Network tab to measure performance.
 It takes 8.74 seconds to get a response from the server when pressing the “Do BOTH Slow Query and
Callout” button.

Analyzing Performance – Developer Console
 Use the Developer Console to analyze server-side performance.
 Apex debug logs will be generated for every server request you perform
while the window is open.
 Several tools are available in the Developer Console to find performance
hotspots.

Analyzing Performance – Developer Console

1) Open the log for
the slow request.

3) Identify the slow
portion and click on the
bar. This loads the
relevant log lines into
the Execution Log.

4) Click on a line in
the Execution Log to
show the stack trace
for the slow query on
the left.

Analyzing Performance – Log Levels
 The default log levels generate a huge amount of output, most of which
is unnecessary for debugging performance issues.
 This also makes the console slower.
 Try lowering the log levels so you can look for slow queries and callouts
first.

Analyzing Performance – Heap Dumps

 The Developer Console can also be used to create Apex
heaps that help in debugging.
 For example, you can use it look at the bind variables for a
query.


 The bind variables will
not show up in the
debug console and may
not be easy to find.
 You can set a heap
dump breakpoint to get
the variable values at
the time the query is
run.


Set a breakpoint
on the line where
the query is run.


 The runtime values
of the variables can
be found in the
Symbols tab of the
heap dump viewer.

Analyzing Performance – Useful Tools
 Developer Console
 Firebug (http://getfirebug.com)
- Web development plugin for Firefox.
 Chrome Developer Tools
- Included with Chrome.
 Workbench (https://workbench.developerforce.com)
- Good for testing SOQL queries.
 Fiddler (http://www.fiddler2.com/fiddler2)
- Windows tool for debugging HTTP traffic, integrates well with IE and Firefox.

Working with Support

 SOQL performance
- Open a case with org Id, user Id, SOQL and bind variables.
- Can add custom single and two column indexes.
 Record locks
- Provide support the org ID and time frame where the issues
occurred.
- Provide the IDs of affected records if possible.

Useful Links

Architect Core Resources
 http://wiki.developerforce.com/page/Architect_Core_Resources
- Guide to Sharing Architecture
- Record Access: Under the Hood
- Best Practices for Deployments with Large Data Volumes
- Asynchronous Processing in Force.com
- VF Performance

Stuart Bernstein Thomas Harris John Tan
ISV Technical Evangelist LMTS, CCE Production SMTS, CCE Technical
Support Enablement

Performance Tuning for Visualforce and Apex

Performance Tuning for Visualforce and Apex

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