Hi Eduard,
This will be almost instantaneous, unless you specify DEFAULT value.
Oracle doesn't need to keep any information of trailing NULL columns in the
data blocks. Oracle will not change row headers until non-null value will be
set.
If you need this column to be NOT NULL, better to add NULL colomn,
set desired value via several smaller updates (range limited by appropriate
WHERE ) and than modify NOT NULL.
If you'll try to ADD NOT NULL with DEFAULT, estimated time will be
full table update :)
Hope this helps
Vadim Gorbounov,
Oracle DBA
BTW, dont you know Dmitry Shirkalin? He also works for flagship.ru.
-----Original Message-----
Sent: Thursday, April 05, 2001 7:16 AM
To: Multiple recipients of list ORACLE-L
Hello List
We are going to change structure of a big table (more than 250.000.000
rows).
We need to add a column with NUMBER type.
I'm unclear how Oracle do this operation.
Does it mean that Oracle have to read and reformat all table
blocks in order to update each row header?
If yes, I can suggest that estimation of the operation's time is about
time of Full Table Scan on the table.
Is it correct? Please explain.
Ed
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