Oracle-L: Re: Data Warehouse experts, a simple question for you

From: <Jared.Still_at_radisys.com>
Date: Mon, 20 May 2002 16:03:23 -0800
Message-ID: <F001.0046568A.20020520160323@fatcity.com>

Joe,

Add a generated PK to the time dimension. The PK is stored as an FK in the fact table.

That way you can select from the time dimension by year, day, qtr, whatever,
and easily pick out the correct fact table rows.

"The Data Warehouse Lifecycle Toolkit" includes a spreadsheet to generate the DDL/DML for a very robust time dimension. I think it has about 20 columns.

Very good book, can't recommend it enough.

Jared

Joe Testa <jtesta_at_dmc-it.com>
Sent by: root_at_fatcity.com
05/20/2002 04:08 PM
Please respond to ORACLE-L

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        Data Warehouse experts, a simple question for you

Ok i'm messing with dimensions.

dm_time to be exact:

create table dm_time

( calendar_date date not null,
  calendar_month number(2) not null,
  calendar_qtr number(1) not null,
  calendar_year number(4) not null);

insert into dm_time values(to_date('20020101','YYYYMMDD'), 1,1,2002); insert into dm_time values(to_date('20030101','YYYYMMDD'), 1,1,2003);

2 rows nice and simple

trying to validate the dimension comes up with an error, my guess is because of the design of the table

where basically calendar_date is child of

calendar_month is child of calendar_qtr is child of calendar_year, wont validate.

the question i have is this, should month really be like 2002-01 with the year included, likewise with qtr, then it will validate ok.

Was the design of dm_time just dont wrong or am i missing something here.

thanks, joe

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Author: Joe Testa
INET: jtesta_at_dmc-it.com

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