Change Data Capture Developer Guide
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Change Data Capture Allocations
Concurrent Client Allocation
| Description | Performance and Unlimited Editions | Enterprise Edition | Developer Edition |
|---|---|---|---|
| Maximum number of concurrent CometD clients (subscribers) across all channels and for all event types | 2,000 | 1,000 | 20 |
Default Allocations
If your org has no add-on licenses, default allocations apply and can't be exceeded. Each Salesforce edition provides a default allocation for the number of events delivered to CometD clients. This allocation doesn’t apply to non-CometD subscribers, such as Apex triggers, flows, and processes. The default allocation is enforced daily to ensure fair sharing of resources in the multitenant environment and to protect the service. Default allocations are not part of the usage-based entitlement.
The number of delivered events to external CometD clients is counted per subscribed client. If you have multiple client subscribers, your usage is added across all subscribers. For example, you have an Unlimited Edition org with a default allocation of 50,000 events in a 24-hour period. Within a few hours, 20,000 event messages are delivered to two subscribed clients. You have consumed 40,000 events, and you are still entitled to 10,000 events within the 24-hour period.
If you exceed the default event delivery allocation, you receive an error. See Streaming API Error Codes in the Streaming API Developer Guide. Event messages that are generated after exceeding the allocation are stored in the event bus. You can retrieve stored event messages as long as they are within the retention window of 72 hours.
| Description | Performance and Unlimited Editions | Enterprise Edition | Developer Edition |
|---|---|---|---|
| Maximum number of entities, including standard and custom objects, that you can
select for Change Data Capture If the same entity is selected in multiple channels, it is counted once toward the allocation. |
5 | 5 | 5 |
| Maximum number of custom channels | 100 | 100 | 100 |
| Event Delivery: maximum number of delivered event notifications in the last 24 hours, shared by all CometD clients | 50,000 | 25,000 | 10,000 |
Change Data Capture Add-On License and Usage-Based Entitlement
To remove the limit on the number of entities that you can select for change notifications, contact Salesforce to purchase the Change Data Capture add-on license.
If your org has the add-on license, your allocation for delivered events to CometD clients moves to a monthly entitlement model. The add-on increases the 24-hour allocation of delivered event notifications by 100,000 per day (3 million a month) as a usage-based entitlement. The entitlement gives you flexibility in how you use your allocations. The entitlement is not as strictly enforced as the default allocation. With the entitlement, you can exceed your 24-hour event delivery allocation by a certain amount. The entitlement is reset every month after your contract start date. Entitlement usage is computed only for production orgs. It is not available in sandbox or trial orgs. For more information, see Usage-based Entitlement Fields.
Salesforce monitors event overages based on a calendar month, starting with your contract start date. If you exceed the monthly entitlement, Salesforce contacts you to discuss your event usage needs. The entitlement used for monitoring monthly event overages is the daily allocation multiplied by 30.
| Description | Performance and Unlimited Editions | Enterprise Edition |
|---|---|---|
| Maximum number of entities, including standard and custom objects, that you can select for Change Data Capture. | No limit | No limit |
| Event Delivery: entitlement for delivered
event notifications, shared by all CometD clients You can exceed this entitlement by a certain amount before receiving an error. Salesforce uses the monthly entitlement for event overage monitoring. The monthly entitlement is returned in the limits REST API resource. |
Last 24 hours: 150,000
(50 K included with org license + 100 K from add-on
license) Monthly entitlement: 4.5 million (1.5 million included with org license + 3 million from add-on license) |
Last 24 hours: 125,000
(25 K included with org license + 100 K from add-on
license) Monthly entitlement: 3.75 million (0.75 million included with org license + 3 million from add-on license) |
To increase the entitlement for event delivery, contact Salesforce to purchase the High-Volume Platform Events add-on.
The maximum event message size that Salesforce can publish is 1 MB. If your entity has hundreds of custom fields or many long text area fields, you could hit this limit. In this case, the change event message isn’t delivered and is replaced by a gap event message. For more information, see Gap Events.
Monitor Your Event Usage
Determine how to check event usage for your org.
For more information about the limit usage values that the limits REST resource returns, see Limits and List Organization Limits in the REST API Developer Guide.
Example: Monitor Your Event Delivery Usage Hourly
To monitor your org's event delivery usage, make a REST API call to the limits resource every hour. The difference between the results obtained in the last 2 hours shows how many events were delivered in the last hour.
For example, you make a call at 12pm, and you see that you have 40,000 events remaining. Then you run the same call at 1pm and see that you have 38,500 events remaining. The returned responses indicate that 1,500 events were delivered to your CometD subscribers between 12pm and 1pm.
These results are examples of the responses that a GET request to the /services/data/v47.0/limits URI would return.
1First call result:
2{
3...
4"MonthlyPlatformEvents" : {
5 "Max" : 50000,
6 "Remaining" : 40000
7 },
8
9...
10}
11
12Second call result:
13{
14...
15"MonthlyPlatformEvents" : {
16 "Max" : 50000,
17 "Remaining" : 38500
18 },
19
20...
21}