RE: NOT NULL vs NULL column in a fact table
- From: "Powell, Mark D" <mark.powell@xxxxxxx>
- To: "oracle-l" <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 4 Sep 2007 16:15:31 -0400
Alter the table adding nullable column
Populate column
alter the table modifying column to be not null
Update statistics
-- Mark D Powell --
Phone (313) 592-5148
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of
genegurevich@xxxxxxxxxxxx
Sent: Tuesday, September 04, 2007 2:59 PM
To: oracle-l
Subject: NOT NULL vs NULL column in a fact table
Hi all
I have several medium to large fact tables to which I need to add a NOT
NULL column. In the past I would do the following:
- copy the data from the fact table to a backup table
- truncate the fact table
- add the new column to the fact table as NOT NULL
- copy the data back from the backup table to the fact table with some
predetermined default value (say, -9) for the new column
- rebuild indices
- reanalyze the fact table.
This time however the number of the tables and the sizes are too big and
I don't think my normal process will complete within a reasonable time.
So I am now considering just adding this column as nullable, and modify
it as not null when older partitions are dropped (in a year or two or
so) and I will ask the reporting team to run the reports for this new
column only for the months starting with the one when this column was
added.
What kind of problems am I asking for?
thank you
Gene Gurevich
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