Re: Is it necessary to rewrite table while increasing the scale of datatype numeric??? - Mailing list pgsql-hackers

From Noah Misch
Subject Re: Is it necessary to rewrite table while increasing the scale of datatype numeric???
Date
Msg-id 20130904113052.GA135734@tornado.leadboat.com
Whole thread Raw
In response to Is it necessary to rewrite table while increasing the scale ofdatatype numeric?  (wangshuo@highgo.com.cn)
Responses Re: Is it necessary to rewrite table while increasing the scale ofdatatype numeric???
List pgsql-hackers
On Wed, Sep 04, 2013 at 12:08:48PM +0800, wangshuo@highgo.com.cn wrote:
> 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.

n_header is part of the numeric field's data.  That's not just pedantry: the
display scale stored in n_header affects how numeric_out() formats the value.

-- 
Noah Misch
EnterpriseDB                                 http://www.enterprisedb.com



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