Re: Re: LOL: 122 one column indexes on 122 column table

From: Stefan Koehler <contact_at_soocs.de>
Date: Fri, 19 Feb 2016 15:28:41 +0100 (CET)
Message-ID: <1634535669.56286.1455892122049.JavaMail.open-xchange_at_app03.ox.hosteurope.de>

Hi Lothar,
the 122 columns are extreme of course, but i just wanted to say that a lot of single column indexes can make sense too. It is not always all for nothing.

> Normally if you want index combine you would go for a bitmap index unless there could be locking issues.

Yes, for sure. However if you look a little bit more closely you also see a mixture of both in SAP BI environments for example (Line-item dimensions vs. High cardinality dimension). Ref: http://scn.sap.com/docs/DOC-46354

Best Regards
Stefan Koehler

Freelance Oracle performance consultant and researcher Homepage: http://www.soocs.de
Twitter: _at_OracleSK

> "l.flatz_at_bluewin.ch" <l.flatz_at_bluewin.ch> hat am 19. Februar 2016 um 14:32 geschrieben:
>
>
> Hi Stefan,
>
> You have all 122 columns in different combinations searched? Hardly.
> It is conceivable, but my experience tells me that most of the time it is pure incompetence.
> I have seen such a situation that you describe with the early "pre-google" web searcher apps. Much more often people don't know that an index can
> have more than one column.
> Normally if you want index combine you would go for a bitmap index unless there could be locking issues.
>
> Regards
>
> Lothar

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Received on Fri Feb 19 2016 - 15:28:41 CET