| 摘要 |
Technique are provided for maintaining pre-computed aggregate views. A pre-computed aggregate view derived from one or more base tables is received, the pre-computed aggregate view including a pre-computed aggregate table and a view definition, the view definition including aggregate functions that can be any combination of sum, sum distinct, count(*), count, count distinct, min, and max, the view definition further including expressions that may be nullable. Changes to the one or more base tables are received, the changes being represented as insertions and deletions and being non-minimal. A set of incremental modifications to the pre-computed aggregate table are derived and applied based on the changes to the one or more base tables, wherein modifications may include any combination of inserts, deletes, and updates. Deriving the set of incremental modifications to the pre-computed aggregate table includes deriving a first table wherein each record, representing an aggregated group of changes, shows for each aggregation function, the contributions of base table changes that are insertions for the group and the contributions of base table changes that are deletions for the group and using some combination of information in the first table, the pre-computed aggregate table, and the one or more base tables from which the pre-computed view is derived. |
