Data sweep in production environment? [closed]

Question

Hi i am a newbie to salesforce. I am trying to learn a easy way to do data sweep on some text fields and replace them with another value in production environment. As far as i know data sweep can be done using a data loader. export the data and import it again. If i want to do it using apex code or any other way instead of using the data loader, is there any other alternative available. I am searching for this information to learn and if some could point me in the right direction or give guidance. it will be helpful.

Thanks in Advance

Answer 1

It sounds like you are looking for Batch Apex. Read up on Using Batch Apex. This touches on a lot of topics and is too broad to provide a comprehensive answer to here. The basic structure is something like:

Service Layer

public with sharing class MyService
{
    public static void setSomeTextField(List<MyObject__c> records)
    {
        for (MyObject__c record : records) // do something
        try
        {
            update records;
        }
        catch (DmlException dmx)
        {
            // determine appropriate error handling scheme
        }
    }
}

Batch Implementation

public with sharing class MyBatch implements Database.Batchable<SObject>
{
    public Database.QueryLocator start(Database.BatchableContext bc)
    {
        return Database.getQueryLocator([
            SELECT ... FROM MyObject__c WHERE ...
        ]);
    }
    public void execute(Database.BatchableContext bc, List<SObject> scope)
    {
        MyService.setSomeTextField((List<MyObject__c>)scope);
    }
    public void finish(Database.BatchableContext bc)
    {
        // optional additional logic here
    }
}

Answer 2

One technique (to avoid governor limits) is to run code like this via excute anonymous:

Contact[] contacts = [select Id from Contact where Field__c = 'old value' limit 5000];
for (Contact c : contacts) {
    c.Field__c = 'new value';
}
update contacts;

and keep repeating until all the data is processed. Works fine for say 100,000 records (just run 20 times) but a batchable is the way to go for large numbers of records.