Re: prefixed index - high clustering factor & high cpu
- From: "Ujang Jaenudin" <ujang.jaenudin@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 24 Oct 2007 13:18:10 +0700
sorry i forgot to tell you about
the wait event of cbc (cache buffers chains) is within the query also.
regards
ujang
On 10/24/07, Ujang Jaenudin <ujang.jaenudin@xxxxxxxxx> wrote:
> all,
>
> I have varchar2 column (transc_id) with the value something like
> this...and this column was indexed (unique index)
>
> 811120980.20070920033742
> 811120980.20071021183003
>
> UPDATE c_transaction SET pgi_status =
> decode(c_status,0,1,1,1,2,1,3,3), ne_status = 1, messagetracking_id =
> NULL, last_processing_dtm = SYSDATE WHERE transc_id = :1 and transc_id
> = :2
>
> at the tkprof the cpu cost is very high , its about 30k, rows returned
> is 1 , io cost is 4 , the cost itself only 4.
>
> the dba_indexes says:
> num_rows = 2195991
> distinct_key = 1507195
> clustering_factor = 1476573
> blevel = 2
> leaf_blocks = 14486
>
> histogram is already there with 254 bucket....
>
> I'm guessing to turn index to reverse key, is it has the benefit impact?
>
> thanks in advance
>
> --
> regards
> ujang
>
--
regards
ujang
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