Is it necessary to rewrite table while increasing the scale ofdatatype numeric？

Hi, Hackers!

I find that it takes a long time when I increase the scale of a numeric
datatype.
By checking the code, I found that's because it needs to rewrite that
table's file.
After checking that table's data file, I found only parameter n_header
changed.
And, I found the data in that numeric field never changed.
So I thank It's not necessary to rewrite the table's file in this case.

Anyone has more idea about this, please come to talk about this!

Best Regards!

      Yours,
      Wang Shuo
      HighGo Software Co.,Ltd.
      September 4, 2013