Provided are techniques for operator isolation based on data security requirements. At a cloud node, a graph is received that includes ingest portions of data and operators. For each of the operators, it is determined whether the operator processes protected data. In response to determining that the operator is tagged with an indication that the operator processes protected data, the operator is forwarded to a tenant secure node for processing. In response to determining that the operator is not tagged with an indication that the operator processes protected data, the operator is forwarded to a tenant general node for processing. Then, while the tenant general node is processing the operator, in response to determining that the operator is processing protected data a tag is associated with the operator to indicate that the operator processes protected data and the operator is forwarded to the tenant secure node for processing.