Join at Extract or later
Posted: Sun Jun 17, 2007 10:11 am
Hello,
I am a newbie in DSS and BI world, have been reading various DW books to improve.
I have a general question regarding the dimensions. OLTP system has a highly normalized structure while DW structures are denormalized.
Using DataStage - When we pull the information from the source system (for the dimensions), the information comes from multiple tables.
Which way is better
1) While pulling the information join the multiple tables and put the information in staging area(RIGHT AT THE SOURCE)
Or
2) Bring the information separately(multiple tables) and then after the information is in staging area then do the joins.
Thanks a million for your time.
Regards
Eric
I am a newbie in DSS and BI world, have been reading various DW books to improve.
I have a general question regarding the dimensions. OLTP system has a highly normalized structure while DW structures are denormalized.
Using DataStage - When we pull the information from the source system (for the dimensions), the information comes from multiple tables.
Which way is better
1) While pulling the information join the multiple tables and put the information in staging area(RIGHT AT THE SOURCE)
Or
2) Bring the information separately(multiple tables) and then after the information is in staging area then do the joins.
Thanks a million for your time.
Regards
Eric