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

From: <>
Date: Fri, 19 Feb 2016 13:32:49 +0000 (GMT)
Message-ID: <>

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.



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Datum : 19/02/2016 - 12:53 (GMT)
An :, Betreff : Re: LOL: 122 one column indexes on 122 column table

Hi Laimis,

> That’s…rude.

… or needed by design. Just think about dynamic queries with all possible predicate combinations - impossible to create proper (composite) indexes for all these cases. It may be a valid approach to index each column and let the optimizer work out the combinations (+ "B-tree to Bitmap Conversions"). They also can be used in joins.

Not everything is as crazy as it looks at first view ;-)

Best Regards
Stefan Koehler

Freelance Oracle performance consultant and researcher Homepage:
Twitter: _at_OracleSK  

> Laimutis Nedzinskas <> hat am 19. Februar 2016 um 10:58 geschrieben:
> Hi..
> I thought I’d seen all.
> Not even close:
> 122 column table.
> 122 one-column indexes on EACH column.
> (BLOBs I don’t count, let them be)
> That’s…rude.
> /Laimis N


Received on Fri Feb 19 2016 - 14:32:49 CET

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