RE: Function based indexes?

yes, you can -- more or less -- by mapping all other possible outcomes to NULL
with a CASE expression. Note however that function-based indexes also store
entries for NULL expression outcomes.
 
By the way, if that value 1 is so special, you might consider to store it in a
separate column. Unless tomorrow the special value is suddenly 42 :-)
 
but why would you bother about a little bit of space? as long as you don't
perform full index scans, the performance will not be affected by the index
size...



kind regards,

Lex.

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From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Rick Stephenson
Sent: Tuesday, December 06, 2005 19:45
To: oracle-l@xxxxxxxxxxxxx
Subject: Function based indexes?



Is there a way to create an index on a column and only index those where the
value meets a certain expression?  For example, if I have a numeric column, can
I just have the index built for those values that equal 1?  I don't query on any
other value, so I don't want to consume the space for the other values.  I am
running EE 9.2.0.3.

 

Thanks,

 

Rick Stephenson

 


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