Aggregation constraints in a query processing system

A method comprising:

• receiving, by at least one hardware processor, a first query directed towards a shared dataset;
• accessing a first set of data from the shared dataset, the first set of data comprising data from a first table of the shared dataset;
• determining, by the at least one hardware processor, that an aggregation constraint policy is attached to the first table, the aggregation constraint policy restricting output of data values stored in the first table;
• performing, by the at least one hardware processor, a uniqueness check on join keys for a join operation associated with the first table, the uniqueness check comprising a verification that at least one row from the first table is not amplified in a result of the join operation;
• enforcing the aggregation constraint policy on the first query based on the verification;
• and
• generating an output to the first query based on the first set of data.

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

• receiving a first query directed towards a shared dataset;
• accessing a first set of data from the shared dataset, the first set of data comprising data from a first table of the shared dataset;
• determining that an aggregation constraint policy is attached to the first table, the aggregation constraint policy restricting output of data values stored in the first table;
• performing a uniqueness check on join keys for a join operation associated with the first table, the uniqueness check comprising a verification that at least one row from the first table is not amplified in a result of the join operation;
• enforcing the aggregation constraint policy on the first query based on the verification;
• and
• generating an output to the first query based on the first set of data.