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I need to identify the Skewness of some SQL's in Teradata. These are different SQL statement like,

  1. CREATE Volatile Table using multiple Tables and involving Multiple Left Join
  2. INSERT SQL from Table and involving multiple LEFT Join

I verified if the target table/VT have proper PI. And it has proper PI. Checked if the LEFT JOIN's are increasing the records, but it isn't.

I need to identify the SKEW Factor of the SQL. I can see ViewPoint has a SKEW Tab. But since the SQL gets executed quickly, ViewPoint data gets vanished. Can anyone help how to get the SKEW data using some SQL or from some DBC table

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eshirvana
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Ankit Srivastava
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  • Please explain what *you* mean by "skewness". – Gordon Linoff Dec 29 '20 at 15:17
  • [how to find skew](https://docs.teradata.com/r/B7Lgdw6r3719WUyiCSJcgw/FbHsNrvLOjLsatR7ILjFkw) – Andrew Dec 29 '20 at 15:17
  • @Andrew This would give me if a Table is Skewed. My concern is to check if I have a SQL using Multiple Table and Joins, is there any way to identify Skewness of the SQL. As mentioned in Viewpoint I can see but i need to know from where that data is getting captured. Any idea? – Ankit Srivastava Dec 29 '20 at 16:09
  • @GordonLinoff Data Skewness in terms of CPU Skew and IO Skew. One AMP doing most work i.e. uneven distribution of data – Ankit Srivastava Dec 29 '20 at 16:10
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    If you have access to the DBQL tables, you can identify what steps are causing problems. You can then go back to the explain for your query, find that step, and see what's going on. – Andrew Dec 29 '20 at 16:48

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