Re: Online Index Rebuild Tuning

Compressing indexes has been an option since 8i, and Jonathan Lewis has done some interesting presentations on this (I witnessed it at our Database Forum in Middelfart this year - very impresive).

In short, it changes the way you should think of concatenated indexes, ie you should put the least selective column first, then compress it. That way you'll end up with very small indexes compared to the old days and ways.

I don't see any drawbacks to this approach except that you of course has to unlearn what you have learned (Yoda?)...

Other index things Jonathan adresses include: It is actually better to index small tables, even one-row tables.

Mogens

Rachel Carmichael wrote:

>http://www.tusc.com/oracle/download/author.html#loneyk
>
>
>--- John Kanagaraj <john.kanagaraj_at_hds.com> wrote:
>
>
>>Mark,
>>
>>
>>
>>>Also, I have heard about compressing indexes, but it is
>>>something I have
>>>never used before. Can anyone shed some light on the topic?
>>>Are there any
>>>drawbacks (ie: reduced IO but increased processing)?
>>>
>>>
>>Kevin Loney presented a paper on this at IOUG 2002 - should be in the
>>archives at www.ioug.org.
>>
>>John Kanagaraj
>>Oracle Applications DBA
>>DB Soft Inc
>>Work : (408) 970 7002
>>
>>Listen to great, commercial-free christian music 24x7x365 at
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>>** The opinions and facts contained in this message are entirely mine
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>> INET: john.kanagaraj_at_hds.com
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