Re: Column Length modification

Just that, i think the option of creating the new object fully with the data and rename afterwards by dropping the original object may not be a good option if the object which we are trying to alter is in TB's and partitioned, thinking if any other possible way to achieve the same?

On Sun, Mar 21, 2021 at 8:09 AM Lok P <loknath.73_at_gmail.com> wrote:

> Thank you Jonathan.
>
> Yes it's exactly the same error ORA-01440: which we are encountering. And
> the column is not having any data with non zero precision. But as we are
> standardizing the data elements across our applications, we want to now not
> allow any junks in future and thus trying to fix the precision thing as
> part of this length modification. This will make things consistent across
> all our applications and easy for understanding.
>
> Now if my understanding is correct, the way you are suggesting i..e
> altering column length as (22,7) (which will not make any ORA-01440 error
> happen )+ having the check constraint added to the table will technically
> help us achieving the same thing (without any additional performance
> overhead) as simply altering the length to number(22,0). But is it
> something that will create confusion and thus we should keep it clean i.e.
> column length (22,0) only without any additional constraint? And to achieve
> that , is the best approach is the one suggested by Ahmed i.e. create the
> object fully with the new structure(i.e. with number(22,0)) and then drop
> the old one and rename the new one?
>
> Regards
> Lok
>
> On Sun, Mar 21, 2021 at 3:30 AM Jonathan Lewis <jlewisoracle_at_gmail.com>
> wrote:
>
>>
>> If you're see an error then show us exactly what it is.
>> I assume it's
>> ORA-01440: column to be modified must be empty to decrease precision or
>> scale
>>
>> You're trying to change a column from (15,5) to (22,0) which means you're
>> going to lose 5 decimal places - do any of the rows have data that isn't
>> purely integer, if not are you happy for the values to change as you go
>> from 5d.p. to integer?
>>
>> If you need 22 digits precision, and no decimal places you could modify
>> your column to (27,5) and then add a check constraint that says (check colX
>> = trunc(colX)) as a way of ensuring that you don't have any non-integer
>> values. (You could update the table,set colX to trunc(colX) where colX !=
>> trunc(colX)before adding the constraint, or you could add the constraint
>> enabled but not validated, then do the update then set the constraint
>> validated. ** or ceiling() or round(), depending on what you think best
>> suits your requirements
>>
>> Regards
>> Jonathan Lewis
>>
>>
>>
>>
>> On Sat, 20 Mar 2021 at 19:10, Lok P <loknath.73_at_gmail.com> wrote:
>>
>>> We are using version 11.2.0.4 of Oracle exadata. Our requirement is to
>>> modify column length of a table from Number(15,5) to Number(22) and we are
>>> seeing errors and its saying to make the column empty before making this
>>> modification. So to achieve this we are thinking of doing this in multiple
>>> steps like
>>>
>>> 1) Add new column(COL_new) with number(22,0) to the same table
>>>
>>> 2)Then update the new column with all the values of original column(say
>>> COL1)
>>>
>>> 3)Then drop the original column(COL1) which is having length
>>> number(15,5) 4)Then rename the new column(COL_NEW) to original i.e. COL1.
>>>
>>> We are in the process of doing multiple such modifications to some big
>>> partition and non partitioned table. And in this process the Update seems
>>> to be a tedious one as it will scan the full table and may lead to row
>>> chaining and also drop the existing column and renaming new columns will
>>> need the application to stop pointing to this object or else they may fail.
>>> Also stats seems to be gathered fully again on the table after this along
>>> with if any index pointing to these columns needs to be recreated. So
>>> multiple issues highlighted with this process by the team. Want to
>>> understand from experts if there exists any better way of achieving this
>>> with minimal interruption and in quick time?
>>>
>>>
>>> Thanks
>>>
>>> Lok
>>>
>>

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