Creating a table

Teradata Debugger

Creating a table

Hi I am new to Teradata and coding all togther so I apologse for any silly questions inadvance :-) 

 

I have tried to create a table using this code below

 

create table tmg.t1 as (
SELECT Item_Name, Product_View_Time_Dttm, Web_Session_Id ,Page_View_Sequence_Num
FROM cis.t2
WHERE Product_View_Time_Dttm BETWEEN DATE -7 AND DATE -1)
with data;

 

if I select the data its works fine but when i try to create a subset table(the select data)  it takes forever, the records am trying to insert into the new table are 26,539,945 records

 

please could any advice how I can create a subset table with these records

 

Thanks Rory

2 REPLIES
rjg
Supporter

Re: Creating a table

Rory,

If you create a table in Teradata and do not define a primary index the first column in this case will be used by default.

Tables are distributed to the Amps based on the Primary index value.

This means all of your data will be distributed by hashing the value of Item_Name.

The behavior you describe indicates the values fo this column are skewed.

You should define a primary index '.......with data  primary index(col1,col2...);'

that will make the combination of columns fairly unique to allow for fairly even data distribution to your amps.

Consider access when choosing your primary index if you can since retreiveing your data by providing the Primary index values will be the most efficient.

 

Rglass

 

 

 

 

Highlighted

Re: Creating a table

Thanks Rglass

 

Yes the problem was the primary index, I needed to specifiy an appropiate primary index

Tags (1)
  • Tags: