GROUP-BY PROCESSING FOR DATA CONTAINING SINGLETON GROUPS

摘要

According to one embodiment of the present invention, a system performs a grouping operation for a database query. The system assigns data elements to groups and aggregates information for a group in response to assigning the group two or more data elements. The system passes the aggregated information for a group of two or more data elements for processing in accordance with the query, and passes information for a data element of a single-member group in a received form for processing in accordance with the query. Embodiments of the present invention further include a method and computer program product for grouping data elements in substantially the same manners described above.

主权项

1. A method of performing a GROUP BY operation for a database query comprising:
receiving one or more blocks of data elements, wherein each data element comprises compressed information; assigning the data elements to groups to form one or more single-member groups and one or more plural-member groups, wherein assigning the data elements comprises:
assigning a data element to a new group to form a single-member group and storing a pointer to a received block containing that data element; andassigning a data element to an existing group to form a plural-member group, decompressing compressed information of the data elements assigned to the plural-member group, and forming aggregated information for the plural-member group from the decompressed information; and passing the aggregated information for each plural-member group for query processing; and passing the compressed information of a data element of a single-member group for query processing.