How Chunking Works with ReportEvent and ListViewEvent

When Salesforce chunks a ReportEvent or ListViewEvent (and their streaming equivalents), it breaks it into multiple events in which most field values are repeated. The exceptions are the Records, Sequence, and EventIdentifier fields. You view all the data from a chunked result by correlating these fields with the ExecutionIdentifier field, which is unique across the chunks.

Let’s describe in more detail the fields of ReportEvent and ListViewEvent (and their storage equivalents) that you use to link together the chunks.

• Records—A JSON string that represents the report or list view data. If Salesforce has chunked the data into multiple events, each event’s Records field contains different data.
• Sequence—An incremental sequence number that indicates the order of multiple events that result from chunking, starting with 1. For example, if Salesforce breaks up an event into five chunks, the first chunk’s Sequence field is 1, the second is 2, and so on up to 5.
• ExecutionIdentifier—A unique identifier for a particular report or list view execution. This identifier differentiates the report or list execution from other executions. If chunking has occurred, this field value is identical across the chunks, and you can use it to link the chunks together to provide a complete data picture.
• EventIdentifier—A unique identifier for each event, including chunked events.

To view all the data chunks from a single report or list view execution, use the Sequence, Records, and ExecutionIdentifier fields in combination.

For example, let’s say a report execution returns 10K rows. Salesforce splits this data into three chunks based on the size of the records, and then creates three separate ReportEvent events. This table shows an example of the field values in the three events; the fields not shown in the table (except EventIdentifier) have identical values across the three events.

SELECT ExecutionIdentifer, Sequence, Records FROM ReportEvent