RE: Suggestions solicited - Change Column Datatype from Number to

Stephane - You asked:

     But why the second CTAS ? What about RENAME ? Seems faster to me ...

Well, it depends on whether you are okay with changing locations of the table. Personally, I'm with you, just accomplish everything with one move of the data. But I figured someone would object, insisting on ending up with everything in the original location.

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

-----Original Message-----
Sent: Thursday, October 24, 2002 4:54 PM To: Multiple recipients of list ORACLE-L to

Rachel Carmichael wrote:
>
> Dennis,
>
> That's a good thought, and it works if you don't have grants,
> constraints or dependencies on the original table.
>
> If you drop table1, you lose them all
>
> Rachel
>
> --- DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM> wrote:
> > 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
> >

Hmmm, generating the suitable script from USER_TAB_PRIVS, USER_CONSTRAINTS, USER_IND_COLUMNS and USER_CONS_COLUMNS is not too difficult ... at least if you are familiar with the dictionary.

But why the second CTAS ? What about RENAME ? Seems faster to me ...

-- 
Regards,

Stephane Faroult
Oriole Software
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Stephane Faroult
  INET: sfaroult_at_oriole.com

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