Database operation using metadata of data sources

In some examples, a computing device determines a data manipulation from a job specification. The device determines a corresponding data-processing instruction using data-source metadata, and determines and executes a corresponding query. In some examples, a device receives search keys. The device searches data-source metadata using the search keys. The device weights a first data source based on producer-consumer relationships between data sources, and ranks the first data source using the weight. In some examples, a device determines structural and content information of a data record. The device determines a data-source identifier from the structural information and stores the content information with the data-source identifier in a database. In some examples, via a user interface, a device receives a job specification and annotation data. The device stores the spec and the annotation data in a metadata repository.