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

From: Laimutis Nedzinskas <laimutis.nedzinskas_at_statoilfuelretail.com>
Date: Fri, 19 Feb 2016 14:31:44 +0000
Message-ID: <AM4PR01MB1474F7128249A65EFC92E8A7F4A00_at_AM4PR01MB1474.eurprd01.prod.exchangelabs.com>



Hi

It all nails down to selectivities then. In this particular case..some columns have names CHARSET. No point.

But insert takes 0.5 seconds on a good hardware. That’s...rude.

But yeah, design is consistent. Agree on that

/Laimis N

-----Original Message-----
From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Stefan Koehler Sent: Friday, February 19, 2016 4:29 PM To: l.flatz_at_bluewin.ch
Cc: oracle-l_at_freelists.org
Subject: Re: Re: LOL: 122 one column indexes on 122 column table

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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i0zX+n{+i^ Received on Fri Feb 19 2016 - 15:31:44 CET

Original text of this message