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Teradata - What is activity count? What is skew factor? How it's working explain briefly?




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asked mar September 20, 2014 06:38 AM  

What is activity count? What is skew factor? How it's working explain briefly?


           

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answered By vishnoiprem   0  
1. activity count indicates the no of rows affected/processed by the last request(no of rows returned to bteq from teradata).

2. skewness refers to the distribution of rows on the amps.
 If some AMPs are having more rows and some very less, then skewness would be high. This would affect the parallelism.

3. Following query gives the skewness for all tables.
SELECT ts.DatabaseName
,ts.TableName,td.CreateTimeStamp AS Created
,td.LastAlterTimeStamp AS LastAltered,td.AccessCount
,td.LastAccessTimeStamp AS LastAccess
,SUM(ts.CurrentPerm) AS CurrentPerm
,SUM(ts.PeakPerm) AS PeakPerm,
(100 - (AVG(ts.CurrentPerm)/MAX(ts.CurrentPerm)*100)) AS SkewFactor
FROM DBC.TableSize ts
JOIN DBC.Tables td
ON ts.DatabaseName = td.DatabaseName
AND ts.TableName = td.TableName
GROUP BY 1,2,3,4,5,6;
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Asked 2 years and 3 months ago ago
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