Updating a fact table ?
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Updating a fact table ?
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.
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.
exhortae- Posts : 30
Join date : 2010-08-01
Re: Updating a fact table ?
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.
Re: Updating a fact table ?
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
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
exhortae- Posts : 30
Join date : 2010-08-01
Re: Updating a fact table ?
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.
Re: Updating a fact table ?
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
exhortae- Posts : 30
Join date : 2010-08-01
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