Oracle-L: RE: Suggestions solicited - Change Column Datatype from Number to

From: <Rick_Cale_at_teamhealth.com>
Date: Thu, 24 Oct 2002 13:18:08 -0800
Message-ID: <F001.004F3190.20021024131808@fatcity.com>

Could you preserve the constraints and indices if you do somthing similar like

create table temp as select * from table1 nologging TRUNCATE table table1

                                                                                        
                                                             ALTER TABLE table1         
                                                           NOLOGGING;

ALTER TABLE table1 MODIFY(column...);

Do a direct load insert

                                                                                        
                                                            ALTER TABLE table1 LOGGING;

DROP TABLE temp

I have not done direct load insert but read it can be done for NOLOGGING Rick

                                                                                                       
                    DENNIS WILLIAMS                                                                    
                    <DWILLIAMS_at_LIFE       To:     Multiple recipients of list ORACLE-L                 
                    TOUCH.COM>             <ORACLE-L_at_fatcity.com>                                      
                    Sent by:              cc:                                                          
                    root_at_fatcity.co       Subject:     RE: Suggestions solicited - Change Column       
                    m                      Datatype from Number to                                     
                                                                                                       
                                                                                                       
                    10/24/2002                                                                         
                    04:35 PM                                                                           
                    Please respond                                                                     
                    to ORACLE-L

Deepak, If there are many columns on these tables, your method may be best. However, this will generate a lot of redo. You can usually accomplish this with a CTAS nologging, which won't generate redo. If you really don't want to change the location, you can:

create table temp as select * from table1 nologging drop table table1
create table table1 (column, column . . . ) as select * from temp nologging

drop table temp

Dennis Williams
DBA, 40%OCP
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Thursday, October 24, 2002 3:15 PM To: Multiple recipients of list ORACLE-L

We have a need to change the datatype of several columns in a table from number to varchar2. Most of the rows have data in these columns hence a direct 'alter table ...' will not work.

We plan to create a temp table, move the data from these colums to that table, modify the column datatype from number to varchar2 and then update the colums with the data that was moved to the temp table.

Any suggestions/comments or a better way to do this ? Oh, and we are on 8.1.7.1

thanx
deepak

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Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

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Received on Thu Oct 24 2002 - 16:18:08 CDT