Ownership Data Skew

Even with all of the work that Salesforce does to maintain correct access for security groups, most customers will never encounter performance issues unless they are performing updates that affect many users or large amounts of data. However, there are certain common configurations that greatly increase the probability of performance problems. When a single user owns more than 10,000 records of an object, we call that condition ownership data skew. One of the common patterns involves customers concentrating ownership of data so that a single user or queue, or all the members of a single role or public group, owns most or all of the records for a particular object.

For example, a customer can assign all of his or her unassigned leads to a dummy user. This practice might seem like a convenient way to park unused data, but it can cause performance issues if those users are moved around the hierarchy, or if they are moved into or out of a role or group that is the source group for a sharing rule. In both cases, Salesforce must adjust a very large number of entries in the sharing tables, which can lead to a long-running recalculation of access rights.

If you do have a compelling reason for assigning ownership to a small number of users, you can minimize possible performance impacts by not assigning the user(s) to a role.