Systems and methods are described for implementation by a streaming data processing system of a processing pipeline that obtains data items from one or more data sources. The one or more data sources may include multiple partitions of a topic or multiple topics. The one or more data sources are defined by a data pattern, a group of tenants, or a process. The implementation of the processing pipeline can include identifying the one or more data sources to obtain data items. The processing pipeline can include a plurality of processing tasks to obtain the data items. The streaming data processing system can utilize a workload coordinator to dynamically assign particular data sources to particular processing tasks. The implementation of the processing pipeline can further include executing the plurality of processing tasks to cause processing tasks to obtain data items from assigned data sources and process the data items.