From: | wangshuo(at)highgo(dot)com(dot)cn |
---|---|
To: | Noah Misch <noah(at)leadboat(dot)com> |
Cc: | Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Is it necessary to rewrite table while increasing the scale of datatype numeric??? |
Date: | 2013-09-05 03:07:43 |
Message-ID: | 007bc903ebd09778bbedbd2282cf0916@highgo.com.cn |
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Lists: | pgsql-hackers |
于 2013-09-04 19:30, Noah Misch 回复:
> On Wed, Sep 04, 2013 at 12:08:48PM +0800, wangshuo(at)highgo(dot)com(dot)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.
>
Noah Misch <noah(at)leadboat(dot)com> wrote:
> 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.
Thanks for your reply.
Just because of what you said, I think increasing scale only lead to
differently
diaplay. There's no difference between 5.25 and 5.2500 in use.
So thers's no need to rewrite the table.
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