Query processing pipelines with single-item and multiple-item query operators

Queries against data sources (such as language-integrated queries to be applied against relational databases) may be prepared for processing by a query processing pipeline. This pipeline performs services including transforming the query into a form more easily applied by the data source, e.g., into SQL, by matching query terms with query operators configured to handle various query operations. Many query processing pipelines include single-item query operators that perform individual operations (e.g., an updating query operator that specifies an updating of individual records of a table.) An integrated query pipeline may be devised that includes both single-item query operators and multiple-item query operators that specify operations on sets of data items. An integrated query processing pipeline may analyze the query to determine whether a single-item or multiple-item operation is specified in order to select an appropriate query operator, which may improve the efficiency and performance of the data source querying.