Various design tools can provide this capability. Oracle??™s Warehouse Builder
(OWB), included with Oracle Enterprise Edition, Standard Edition, and Standard
Edition One databases (since 2006), provides a metadata repository and also the
capability to import metadata from operational tables and then forward-engineer
new schema and tables. A data warehouse designer creates columns for the new
tables and builds constraints for the new schema. Maps are then created between
source and target columns with appropriate transformations. DML scripts for creation
of new tables, and PL/SQL or SQL*Loader scripts for ETL are automatically
generated.
As noted previously, data warehouses historically have had a different set of usage
characteristics from those of an OLTP database. One aspect that makes it easier to
meet data warehousing performance requirements is the high percentage of read
operations. Oracle??™s locking model, described in detail in Chapter 8, is ideally suited
for data warehouse operations. Oracle doesn??™t place any locks onto data that??™s being
read, thus reducing contention and resource requirements for situations where there
are a lot of database reads.
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