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Re: Help me understand the contents of INDEX_HISTOGRAM please...

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: 21 Jan 2002 06:27:48 -0800
Message-ID: <a20d28ee.0201210627.4f25a83a@posting.google.com>


monsri_at_my-deja.com (Sri) wrote in message news:<6425692a.0201210352.3ff0a7b7_at_posting.google.com>...
> Hello,
>
> Could you please help me interpret the contents of INDEX_HISTOGRAM
> once I've analyzed an index (I was pretty bad at maths when in
> high school, and much worse in the subject statistics...) ? So if you
> take the following output for ex., what conclusion would you draw
> from the figures this view currently contains ??, what do they mean ?:
>
> REPEAT_COUNT KEYS_WITH_REPEAT_COUNT
> ------------ ----------------------
> 0 0
> 1 154
> 2 101
> 3 24
> 4 16
> 5 4
> 6 1
> 7 0
> 8 0
> 9 0
> 10 0
> 11 0
> 12 0
> 13 0
> 14 0
> 15 0
>
> 16 rows selected.
>
> Thanks a lot...
> Sri

There 154 keys which occurs once, 101 which occurs twice etc, etc. Histograms like this are a result of analyze index validate structure. The histograms generated by analyze table ... compute|estimate for all indexed columns are more accurate.

Hth

Sybrand Bakker
Senior Oracle DBA Received on Mon Jan 21 2002 - 08:27:48 CST

Original text of this message

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