Pros and Cons of Choosing Pagination in Salesforce.

Pros and Cons of Choosing Pagination in Salesforce.

Visualforce StandardSetController

The StandardSetController is an extremely powerful tool with built-in functionality that you can use to greatly simplify the custom code in your Visualforce pages. Because the server returns only the data for the page being requested, the StandardSetController can significantly reduce view state, especially compared to the view state you would get while using SOQL.

Pros

· Manages data sets on the server, which reduces page state and increases performance

·  Allows you to paginate over large data sets that have up to 10,000 records

·  Includes built-in functionality such as next, previous, first, last, getResultSize, and other methods that can simplify your page

·  Allows you to paginate forward and backward or to any page within the result set

·  Uses a server-side cursor to cache the entire result set, so results will not change if data changes in the database while a user is paginating from one page to the next

Cons

·  Has built-in functionality that results in a very small increase in view state size

·  Can be used only in Apex

You can find more information about StandardSetController in our Visualforce documentation here.

Example: Retrieving Data in Apex to Paginate with the StandardSetController

public class opportunityList {

    public ApexPages.StandardSetController setCon {

        get {

            if(setCon == null) {

                setCon = new ApexPages.StandardSetController(Database.getQueryLocator(

                    [SELECT Name, StageName, Amount, Account.Name, Account.Named_Account__c FROM Opportunity where Account.BillingState = ‘California’ and Status__c = ‘Open’]));

            }

            return setCon;

        }

        set;

    }

    // Initialize setCon and return a list of records

    public List getOpportunities() {

        return (List) setCon.getRecords();

    }

}

OFFSET Clauses within SOQL Queries

With Salesforce SOQL, you can add an OFFSET clause, as well as a limit specifying a start point and a range of records to retrieve for a page, within your queries. This functionality allows you to implement your own pagination with SOQL queries without having to store the entire data set in memory. As a user moves from one page to the next, each page request executes a query to return the specific records required for that page.

Pros

·  Can be used in SOQL executed within the SOAP API, the REST API, or Apex

·  Gives you the ability to build robust pagination using the Force.com APIs without having to store the entire data set in the Web application

Cons

· Supports OFFSET clauses only for ranges of 2,000 or fewer records

· No server-side cursor is created to cache the full result set for future OFFSET queries. This means that what you see in each page of results reflects what is in the database at the time that you submitted your request. So if someone modifies the underlying data while you're paginating over large data sets, what you saw in the previous or following pages might have changed.

·  As users move from one page the next in the result set, each of their requests for page results executes a query against the database.

· If you want to build advanced pagination functionality that displays a specific number of result pages, you must use a SOQL query to retrieve the total number of records before you execute the query containing the OFFSET clause. Executing this SOQL query to count the records affects performance and limits usage.

While many developers view OFFSET as the tool of choice for pagination, we will see that there are many cases in which it is not the tool of choice from a performance perspective.

To read more about OFFSET, see its Force.com SOQL and SOSL Reference topichere.

Example: Retrieving Data With OFFSET to build Custom Pagination

This query returns the first 25 records of our result set.

SELECT Name, StageName, Amount, Account.Name,
 Account.Named_Account__c 
  FROM Opportunity 
 WHERE Account.BillingState = ‘California’
   AND Status__c = ‘Open’
 ORDER BY Account.Name
 LIMIT 25
OFFSET 0

When the user selects the next page in the result set, this query returns the next set of 25 records.

SELECT Name, StageName, Amount, Account.Name, 
Account.Named_Account__c 
  FROM Opportunity 
 WHERE Account.BillingState = ‘California’ and Status__c = ‘Open’
 ORDER BY Account.Name
 LIMIT 25
OFFSET 25

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