Dynamic parallel aggregation with hybrid batch flushing

A non-transitory computer-readable medium storing one or more sequences of instructions which, when executed by one or more processors, cause performing of:

• executing a query execution plan, said query execution plan including a first aggregation operator and a second aggregation operator that is a record source for said first aggregation operator, wherein said first aggregation operator and said second aggregation operator perform the same aggregation operation, wherein executing the query execution plan comprises executing the second aggregation operator, wherein executing the second aggregation operator comprises:
• generating an initial version of a batch of aggregation records;
• after generating said initial version of said batch of aggregation records, determining whether a first record may be aggregated with any aggregation record in said batch of aggregation records;
• and
• in response to determining that said first record may not be aggregated with any aggregation record of said batch of aggregation records, sending said first record to said first aggregation operator.

A database system comprising:

• a network;
• a query execution plan including a first aggregation operator and a second aggregation operator that is a record source for said first aggregation operator, wherein said first aggregation operator and said second aggregation operator perform the same aggregation operation, wherein executing the query execution plan comprises executing the second aggregation operator;
• a first plurality of computing devices executing the first aggregation operator;
• a second plurality of computing devices executing the second aggregation operator comprising:
• generating an initial version of a batch of aggregation records;
• after generating said initial version of said batch of aggregation records, determining whether a first record may be aggregated with any aggregation record in said batch of aggregation records;
• and
• in response to determining that said first record may not be aggregated with any aggregation record of said batch of aggregation records, sending said first record to said first aggregation operator over said network.