What is Batch Apex?

Batch Apex allows you to:
● Process large volumes of data
● Avoid governor limit issues
● Run jobs asynchronously
● Monitor progress

A batch job processes records in chunks (batches).

Batch Apex Interface

A Batch class must implement:

Database.Batchable<SObject>

And define three methods:

● start()
● execute()
● finish()

Batch Execution Flow

1. start() → Identify records

2. execute() → Process each batch

3. finish() → Post-processing

Each batch has its own governor limits.

Real-World Example – Update Old Accounts

Business Requirement

Update all Accounts created before 2020 → Set Status__c = 'Legacy'

Batch Class

Code

public class LegacyAccountBatch
    implements Database.Batchable<SObject> {

    public Database.QueryLocator start(
        Database.BatchableContext bc) {

        return Database.getQueryLocator(
            'SELECT Id, CreatedDate FROM Account WHERE CreatedDate < 2020-01-01'
        );
    }

    public void execute(
        Database.BatchableContext bc,
        List<Account> scope) {

        for(Account acc : scope) {
            acc.Status__c = 'Legacy';
        }

        update scope;
    }

    public void finish(Database.BatchableContext bc) {
        System.debug('Batch processing completed');
    }
}

Run Batch Job

Database.executeBatch(new LegacyAccountBatch(), 200);

Output:

Accounts updated in batches of 200
Batch job completed successfully

Batch Size Control

Batch size determines:
● How many records processed per execution
● Memory usage
● Execution speed

Typical sizes:
● 100–200 (safe default)

Monitoring Batch Jobs

Go to:

Setup → Apex Jobs

View:
● Status
● Processed records
● Errors

Stateful Batch

If you need to preserve state across batches:

implements Database.Stateful

Useful for counters and summaries.

Common Pitfalls

● Large batch size causing heap issues

● Hardcoded queries
● Missing error handling
● Unnecessary state usage

Productivity Tips

● Start with small batch size

● Monitor job logs
● Avoid heavy logic inside execute
● Test with sample data

Conclusion

You now understand:
● Batch Apex fundamentals

● Execution lifecycle
● Batch sizing
● Monitoring
● Large data processing

Keep Exploring! 🔍

Apex Beginner to Advance

Batch Apex