Updating a fact table ?

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Updating a fact table ?

Post  exhortae on Fri Jun 15, 2012 2:48 pm

Hi,

I have a fact table with approximately 16 columns, each night I insert in this fact table about 100 000 rows, but at that time I only have the information to fill 10 columns. It's only the next day that I can update the missing 6 columns (when the information is available).

I may add that I don't update all the 100 000 rows but only 880 - 1000 rows. And I wonder which one of these two methods is the best :

* To update the fact table or,
* To create another fact table with only the 6 columns missing and make a 1 to 1 relation between the two tables (2 columns in the first fact table joined to two columns of the other table)


Thank you.

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Re: Updating a fact table ?

Post  ngalemmo on Fri Jun 15, 2012 3:42 pm

It depends on what the fact table and the late arriving items represent. There is simply not enough information to recommend one way or the other.
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Re: Updating a fact table ?

Post  exhortae on Sat Jun 16, 2012 4:38 am

Hi,

The first fact table consists of an inventory of unpaid loans (unpaid at day - 2 of the report), the second fact table is a transaction one consisting of payments made on some of the unpaid loans of the first fact table (at day - 1 of the report).

the users will query these fact tables together (example : what is the amount paid on an unpaid loan and since when the loan was unpaid....)


thanks

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Re: Updating a fact table ?

Post  John Simon on Tue Jun 19, 2012 8:23 pm

Just update it. Thomas Kejser on his blog shows that updates aren't as bad as people believe in terms of performance, and can be faster than an insert.

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Re: Updating a fact table ?

Post  exhortae on Wed Jun 27, 2012 2:47 pm

John Simon wrote:Just update it. Thomas Kejser on his blog shows that updates aren't as bad as people believe in terms of performance, and can be faster than an insert.

Thanks, I guess I need to try it

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