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But what if you want to just remove the index from optimizer consideration for a
limited time, such as when you are testing performance? With the invisible option,
an index is not considered as a possible step in an access path, but updates and
deletes to the underlying data are still applied to the index.
Partitioning
With the Enterprise Editions of Oracle8 and beyond, youcan purchase the Partitioning
Option. As the name implies, this option allows youto partition tables and
indexes. Partitioning a data structure means that you can divide the information in
the structure among multiple physical storage areas. A partitioned data structure is
divided based on column values in the table. You can partition tables based on the
range of column values in the table (often date ranges), or as the result of a hash
function (which returns a value based on a calculation performed on the values in
one or more columns). As of Oracle9i you can also use a list of values to define a partition,
which can be particularly useful in a data warehouse environment.


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