| 摘要 |
A Decision Support System (DSS) coalescer offloads and transforms data from an online statistical gathering database to a report query database adapted for report generation. The coalescer generates and populates a query database structured for query data retrieval, in contrast to realtime access transaction storage as in the online database. Configurations transform the online database into a star join schema (table structure) that centralizes database "facts" in a central table and forms associations to database "dimensions" upon which a query is likely to be based. The facts refer to items which tend to change regularly over time, such as sales volumes and unit shipped. Conversely, the dimensions include more static values such as time (e.g. days, weeks, and quarters) and geographic regions, such as states and countries. The resulting query model (schema) includes relatively small dimensions tables associated with (i.e. having a schema association to) a relatively larger fact table.
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