Refresh
Refreshing a warehouse consists in propagating updates on
source data to correspondingly update the base data and
derived data stored in the warehouse. There are two sets of
issues to consider: when to refresh, and how to refresh.
Usually, the warehouse is refreshed periodically (e.g., daily or
weekly). Only if some OLAP queries need current data (e.g.,
up to the minute stock quotes), is it necessary to propagate
every update. The refresh policy is set by the warehouse
administrator, depending on user needs and traffic, and may
be different for different sources.
RefreshRefreshing a warehouse consists in propagating updates onsource data to correspondingly update the base data andderived data stored in the warehouse. There are two sets ofissues to consider: when to refresh, and how to refresh.Usually, the warehouse is refreshed periodically (e.g., daily orweekly). Only if some OLAP queries need current data (e.g.,up to the minute stock quotes), is it necessary to propagateevery update. The refresh policy is set by the warehouseadministrator, depending on user needs and traffic, and maybe different for different sources.
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