RE: How's this for space saving:
- From: "Bruce McCartney" <bruce.mccartney@xxxxxxxxxxxxxxxxx>
- To: <jonathan@xxxxxxxxxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 13 Jul 2005 09:53:17 -0600
Hi Johnathon,
We got caught trying to use the OPT_CMPR_COUNT to determine if it would be
benefitial to compress the indexes of a ERP system which had evoved to "an
index for each report" with massive redundancy in the columns. I posted a
question to oracle on the algorithm use to calculate that value and got no
reponse, anyone on the list know what that algorithm might look like?
We saw some very strange values before and after index rebuilds...
>Validate index XXX;
>select opt_cmpr_count, opt_compr_pctsave from index_stats;
>
>OPT_CMPR_COUNT OPT_COMPR_PCTSAVE
>-------------- -----------------
> 3 233
>
>So if I compress this index, I can reduce it's space
>usage by 233% ! (And I've only just created it at
>pctfree = 10 - so that's not because of current
>empty space).
>
>
>Regards
>
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