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Editorial Team
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Asked: 2026-05-26T03:28:12+00:00

Lets say i have a table with the following definition create table dummy (col1

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Lets say i have a table with the following definition

create table dummy (col1 number(9) not null)

All the values in this dummy.col1 are 7 digit long. Now i want to reduce the length of this column from 9 – 7 using alter command. Oracle gives me error that column to be modified must be empty to decrease precision or scale. Makes sense.

I want to ask is there any work around to reduce the column size?

  • I can’t delete the values in the column.
  • I can’t copy values from this column to another since it has trillions of data.
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1 Answer

  1. Editorial Team

    The column size has no relationship to how the data is physically stored (they are variable length)

    e.g. ’23’ in a number(2) will take exactly the same space if stored in a number(38)

    It is purely a constraint on the maximum number that can be stored in the column therefore you could just add a constraint on the column:

    ALTER TABLE dummy ADD 
CONSTRAINT c1
CHECK (col1 < 9999999)
ENABLE
VALIDATE;

    if you want it to go a little quicker change VALIDATE to NOVALIDATE obviously this will not check the validity of the existing data.

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