Batch Apex Governor Limits
Keep in mind the following governor limits for batch Apex.
- Up to 5 batch jobs can be queued or active concurrently.
- Up to 100 Holding batch jobs can be held in the Apex flex queue.
- In a running test, you can submit a maximum of 5 batch jobs.
- The maximum number of batch Apex method executions per 24-hour period is 250,000, or the number of user licenses in your org multiplied by 200—whichever is greater. Method executions include executions of the start, execute, and finish methods. This limit is for your entire org and is shared with all asynchronous Apex: Batch Apex, Queueable Apex, scheduled Apex, and future methods. To check how many asynchronous Apex executions are available, make a request to the REST API limits resource. See List Organization Limits in the Force.com REST API Developer Guide. The licenses that count toward this limit are full Salesforce user licenses or Force.com App Subscription user licenses. Chatter Free, Chatter customer users, Customer Portal User, and partner portal User licenses aren’t included.
- The batch Apex start method can have up to 15 query cursors open at a time per user. The batch Apex execute and finish methods each have a limit of five open query cursors per user.
- A maximum of 50 million records can be returned in the Database.QueryLocator object. If more than 50 million records are returned, the batch job is immediately terminated and marked as Failed.
- If the start method of the batch class returns a QueryLocator, the optional scope parameter of Database.executeBatchcan have a maximum value of 2,000. If set to a higher value, Salesforce chunks the records returned by the QueryLocator into smaller batches of up to 2,000 records. If the start method of the batch class returns an iterable, the scope parameter value has no upper limit. However, if you use a high number, you can run into other limits.
- If no size is specified with the optional scope parameter of Database.executeBatch, Salesforce chunks the records returned by the start method into batches of 200. The system then passes each batch to the execute method. Apex governor limits are reset for each execution of execute.
- The start, execute, and finish methods can implement up to 100 callouts each.
- Only one batch Apex job's start method can run at a time in an org. Batch jobs that haven’t started yet remain in the queue until they're started. Note that this limit doesn’t cause any batch job to fail and execute methods of batch Apex jobs still run in parallel if more than one job is running.
Batch Apex Best Practices
- Use extreme care if you are planning to invoke a batch job from a trigger. You must be able to guarantee that the trigger will not add more batch jobs than the limit. In particular, consider API bulk updates, import wizards, mass record changes through the user interface, and all cases where more than one record can be updated at a time.
- When you call Database.executeBatch, Salesforce only places the job in the queue. Actual execution can be delayed based on service availability.
- When testing your batch Apex, you can test only one execution of the execute method. Use the scope parameter of the executeBatch method to limit the number of records passed into the execute method to ensure that you aren’t running into governor limits.
- The executeBatch method starts an asynchronous process. When you test batch Apex, make certain that the asynchronously processed batch job is finished before testing against the results. Use the Test methods startTest and stopTest around the executeBatch method to ensure that it finishes before continuing your test.
- Use Database.Stateful with the class definition if you want to share instance member variables or data across job transactions. Otherwise, all member variables are reset to their initial state at the start of each transaction.
- Methods declared as future aren’t allowed in classes that implement the Database.Batchable interface.
- Methods declared as future can’t be called from a batch Apex class.
- When a batch Apex job is run, email notifications are sent to the user who submitted the batch job. If the code is included in a managed package and the subscribing org is running the batch job, notifications are sent to the recipient listed in the Apex Exception Notification Recipient field.
- Each method execution uses the standard governor limits anonymous block, Visualforce controller, or WSDL method.
- Each batch Apex invocation creates an AsyncApexJob record. To construct a SOQL query to retrieve the job’s status, number of errors, progress, and submitter, use the AsyncApexJob record’s ID. For more information about the AsyncApexJob object, see AsyncApexJob in the Object Reference for Salesforce and Force.com.
- For each 10,000 AsyncApexJob records, Apex creates an AsyncApexJob record of type BatchApexWorker for internal use. When querying for all AsyncApexJob records, we recommend that you filter out records of type BatchApexWorker using the JobType field. Otherwise, the query returns one more record for every 10,000 AsyncApexJob records. For more information about the AsyncApexJob object, see AsyncApexJob in the Object Reference for Salesforce and Force.com.
- All methods in the class must be defined as global or public.
- For a sharing recalculation, we recommend that the execute method delete and then re-create all Apex managed sharing for the records in the batch. This process ensures that sharing is accurate and complete.
- Batch jobs queued before a Salesforce service maintenance downtime remain in the queue. After service downtime ends and when system resources become available, the queued batch jobs are executed. If a batch job was running when downtime occurred, the batch execution is rolled back and restarted after the service comes back up.
- Minimize the number of batches, if possible. Salesforce uses a queue-based framework to handle asynchronous processes from such sources as future methods and batch Apex. This queue is used to balance request workload across organizations. If more than 2,000 unprocessed requests from a single organization are in the queue, any additional requests from the same organization will be delayed while the queue handles requests from other organizations.
- Ensure that batch jobs execute as fast as possible. To ensure fast execution of batch jobs, minimize Web service callout times and tune queries used in your batch Apex code. The longer the batch job executes, the more likely other queued jobs are delayed when many jobs are in the queue.
- If you use batch Apex with Database.QueryLocator to access external objects via an OData adapter for Salesforce Connect:
- You must enable Request Row Counts on the external data source, and each response from the external system must include the total row count of the result set.
- We recommend enabling Server Driven Pagination on the external data source and having the external system determine page sizes and batch boundaries for large result sets. Typically, server-driven paging can adjust batch boundaries to accommodate changing data sets more effectively than client-driven paging.When Server Driven Pagination is disabled on the external data source, the OData adapter controls the paging behavior (client-driven). If external object records are added to the external system while a job runs, other records can be processed twice. If external object records are deleted from the external system while a job runs, other records can be skipped.
- When Server Driven Pagination is enabled on the external data source, the batch size at runtime is the smaller of the following:
- Batch size specified in the scope parameter of Database.executeBatch. Default is 200 records.
- Page size returned by the external system. We recommend that you set up your external system to return page sizes of 200 or fewer records.
Chaining Batch Jobs
Starting with API version 26.0, you can start another batch job from an existing batch job to chain jobs together. Chain a batch job to start a job after another one finishes and when your job requires batch processing, such as when processing large data volumes. Otherwise, if batch processing isn’t needed, consider using Queueable Apex.
You can chain a batch job by calling Database.executeBatch or System.scheduleBatch from the finish method of the current batch class. The new batch job will start after the current batch job finishes.
For previous API versions, you can’t call Database.executeBatch or System.scheduleBatch from any batch Apex method. The version that’s used is the version of the running batch class that starts or schedules another batch job. If the finishmethod in the running batch class calls a method in a helper class to start the batch job, the API version of the helper class doesn’t matter.
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