Number of Buckets in Histogram? 
Author Message
 Number of Buckets in Histogram?

Hi,

Is there any kind of formulaeic way to appropriately select the number of
buckets for a histogram in an ANALYZE statement?

The oracle manual does not provide any insight into this, simply saying to
experiment with different values (also stating that a size of 75 is
recommended for most data distributions...and I have no idea what that is
supposed to mean).

I have a table of 1 million rows and one column in that table has 6 distinct
values, skewed.  Does this mean I should create a 6 bucket histogram on this
column?  Is there a relationship between cardinality of the column and the
appropriate histogram value?  

What about a different column in this table that has 300 distinct values which
are skewed.  The maximum number of buckets on a histogram is 254.  What do I
do?

I would love to know if anyone has a mathematical formula or logical algorithm
which I can use to determine how many buckets to include in analyze
statements.

Thanks,

Gavin

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Mon, 24 May 2004 03:53:19 GMT
 Number of Buckets in Histogram?

Hi,

There is a script in Steve Adams site (IIRC histogram_helper.sql ??)
have a look there.. http://www.ixora.com.au



Tue, 25 May 2004 04:26:54 GMT
 
 [ 2 post ] 

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