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Message Posted: Fri, 12 Jan 2007 @ 14:05:26 GMT
How do you obtain the skew of the table?
I did this:
CREATE SET TABLE table_a ( TableCode CHAR(5), TableData VARCHAR(995), loaddate DATE) PRIMARY INDEX ( TableCode );
Then, I filled it with 2000 rows.
Then, I try this query:
select cast((cast((maxrows - avgrows) as decimal(18,5)) / (nullif(maxrows,0)))*100 as decimal(9,3)) AS Rowskew, cast(MAX(sub.nbr_rows) as decimal(12,0)) AS maxrows, cast( AVE(sub.nbr_rows)as decimal(18,5)) AS avgrows from ( select hashamp(hashbucket(hashrow(tablecode))) as primaryamp, count(*) nbr_rows from table_a group by 1 ) sub;
And this is the results:
Rowskew maxrows avgrows 38,657 27 16,56250
If this is right, there is a 38 (aprox) of skew in the table.
I'm do it well?
Castelli, Emanuel Alejandro
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