Contact Mass Update – Apex CPU Time Limit Exceeded?
Question
I am trying to perform a mass update on Contact records using Execute Anonymous, but I keep getting the following error:
System.LimitException: Apex CPU Time Limit Exceeded
Here is the code I am using:
List<Contact> contactList = [SELECT Id, Mass_Update_Checkbox__c FROM Contact LIMIT 1000];
for (Contact contact : contactList) {
contact.Mass_Update_Checkbox__c = TRUE;
}
update contactList;What is causing this error, and how can I optimize my approach to avoid hitting the CPU time limit?
Answer
The error occurs because iterating over a large number of records in a loop and updating them directly in-memory can cause excessive CPU time consumption. Instead of a loop, consider using a more efficient approach like batch processing.
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One solution is to use a Batch Apex class to handle the update in chunks, reducing CPU time per transaction.
Batch Apex Approach
public class ContactMassUpdateBatch implements Database.Batchable<sObject> {
public Database.QueryLocator start(Database.BatchableContext bc) {
return Database.getQueryLocator('SELECT Id FROM Contact WHERE Mass_Update_Checkbox__c = FALSE');
}
public void execute(Database.BatchableContext bc, List<Contact> scope) {
for (Contact c : scope) {
c.Mass_Update_Checkbox__c = TRUE;
}
update scope;
}
public void finish(Database.BatchableContext bc) {}
}To execute the batch, run the following in Execute Anonymous:
Database.executeBatch(new ContactMassUpdateBatch(), 200);Swiss Army Knife Batch Processing Approach
An alternative is a more flexible batch processing utility that allows executing mass updates dynamically using an anonymous execution batch pattern.
Database.executeBatch(
new ExecAnonBatch(
Generators.fromQuery('SELECT Id FROM Contact'),
Executors.updateField(Contact.Mass_Update_Checkbox__c, true))
);This approach is part of a broader utility that enables bulk updates, record creation, deletion, undeleting, and more. Here is an example implementation:
public class ExecAnonBatch implements Database.Batchable<Object> {
public interface generator {
Object generate();
}
public interface executor {
void execute(Object[] values);
}
generator gen;
executor exec;
public ExecAnonBatch(generator theGenerator, executor theExecutor) {
gen = theGenerator;
exec = theExecutor;
}
public Iterable<Object> start(Database.BatchableContext context) {
return (Iterable<Object>) gen.generate();
}
public void execute(Database.BatchableContext context, Object[] scope) {
exec.execute(scope);
}
public void finish(Database.BatchableContext context) {}
}
public class Generators {
class QueryGenerator implements ExecAnonBatch.generator {
String queryString;
QueryGenerator(String query) {
queryString = query;
}
public Object generate() {
return Database.getQueryLocator(queryString);
}
}
public static ExecAnonBatch.generator fromQuery(String query) {
return new QueryGenerator(query);
}
}
public class Executors {
class FieldUpdate implements ExecAnonBatch.executor {
SObjectField field;
Object value;
FieldUpdate(SObjectField updateField, Object fieldValue) {
field = updateField;
value = fieldValue;
}
public void execute(Object[] scope) {
SObject[] records = (SObject[])scope;
for(SObject record: records) {
record.put(field, value);
}
Database.update(records, false);
}
}
public static ExecAnonBatch.executor updateField(SObjectField field, Object value) {
return new FieldUpdate(field, value);
}
}Unit Test for the Swiss Army Knife Batch
@isTest
class ExecAnonBatchTest {
@isTest
static void test() {
Test.startTest();
Database.executeBatch(
new ExecAnonBatch(
Generators.fromQuery('SELECT Id FROM User LIMIT 1'),
Executors.updateField(User.LastName, 'Doe')));
Test.stopTest();
System.assertEquals('Doe', [SELECT LastName FROM User ORDER BY LastModifiedDate DESC LIMIT 1].LastName);
}
}Accelerate Your Career with Salesforce Training in Mumbai
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