Re: Indexes for selecting distinct values

"JTommaney" <cdos_jtommaney_at_comcast.net> wrote:
> Bitmaps indexes have some significant concurrency issues if the cust
> table is updated frequently. They can also be impacted if there are
> incremental loads against the tables. Don't implement unless you
> understand these issues.
>
> Depending on your application requirements, MViews can significantly
> speed up the query, however I don't see a way to get the query to
> Incremental/Fast Refresh. You would likely get an ORA-12015: cannot
> create a fast refresh materialized view from a complex query error (
> The union essentially implies that a sort operation goes on before
> identifying if that is a 'new' row ). You could create a Complete
> refresh materialized view, however.

Perhaps do a union of 3 materialized views, rather than a materialized view of 3 unions?

Xho

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