Re: Performance and CHECK constraints

What you are describing is the Partition View concept. Stable from around 7.3.3, although published a little earlier. Deprecated for oracle 8

Have a look on my web-site under

    Features -> Partition Views

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

eln wrote in message <37E92C89.70D666A4_at_corp.earthlink.net>...
>I read somewhere that on a VIEW that references multiple tables (via a
>UNION) a CHECK CONSTRAINT can speed access in certain cases. For
>example, if the VIEW joins several tables that have monthly data (say
>for the last 12 months) and each table has a CHECK CONSTRAINT that
>limits the data to a specific month, then any query against that VIEW
>refereencing the date will not attempt to search any of the the tables
>behind the VIEW that the CHECK CONSTRAINT says can't be in that table.
>In other words Oracle looks at the CHECK CONSTRAINT and determines that
>looking in a particular table is not needed because of the constraint.
>Oracle in this case doesn't even look in the indexes, it just skips that
>table.
>
>Is this a true statement?
>
>Any help is appreciated.
>
>
>
>
Received on Wed Sep 22 1999 - 14:32:55 CDT