Projection constraint policies in a database system

A system comprising:

• one or more hardware processors of a machine;
• and
• at least one memory storing instructions that, when executed by the one or more hardware processors, cause the system to perform operations comprising:
• receiving a query directed to a shared dataset within a database system, the shared dataset including data values organized in a plurality of columns;
• identifying, by the at least one or more hardware processors, a set of data within the shared dataset selectable to respond to the query, the set of data associated with one or more columns subject to a projection constraint policy;
• determining the projection constraint policy applies to the one or more columns based on a context associated with the query, the context determined based on a data sharing agreement;
• processing the query in accordance with the projection constraint policy, the processing of the query including:
• selectively restricting projection of the data values from the one or more columns, and
• selectively permitting a specified operation on the set of data to generate an output;
• and
• providing the output to the query that complies with the projection constraint policy, the output providing derived data based on the specified operation on the set of data without revealing the data values.

A machine-storage medium embodying instructions that, when executed by a machine, cause the machine to perform operations comprising:

• receiving a query directed to a shared dataset within a database system, the shared dataset including data values organized in a plurality of columns;
• identifying, by at least one hardware processor, a set of data within the shared dataset selectable to respond to the query, the set of data associated with one or more columns subject to a projection constraint policy;
• determining the projection constraint policy applies to the one or more columns based on a context associated with the query, the context determined based on a data sharing agreement;
• processing the query in accordance with the projection constraint policy, the processing of the query including:
• selectively restricting projection of the data values from the one or more columns, and
• selectively permitting a specified operation on the set of data to generate an output;
• and
• providing the output to the query that complies with the projection constraint policy, the output providing derived data based on the specified operation on the set of data without revealing the data values.