Re: Doc: fix the rewrite condition when executing ALTER TABLE ADD COLUMN

On 2025-01-03 01:25, Robert Treat wrote:
> On Tue, Dec 3, 2024 at 3:13 AM Masahiro Ikeda
> <ikedamsh(at)oss(dot)nttdata(dot)com> wrote:
>>
>> Hi,
>>
>> The documentation seems to overlook the rewrite condition
>> when executing ALTER TABLE ADD COLUMN.
>>
>> The current document states that a volatile DEFAULT will
>> trigger a rewrite of the table and its indexes. However, the
>> table and its indexes will also be rewritten when an IDENTITY
>> column is added, or when a column with a domain data type that
>> has constraints is added.
>>
>> What do you think?
>>
>
> We still see a number of people asking (or confused) about table
> rewrites when adding columns, so I think the initial tip should
> remain, though I think it can be cleaned up a little.
>
> In the second section (alter_table.sgml) I liked the idea of adding
> these additional examples, though I tweaked the wording a bit to
> (hopefully) make it a little easier to read.
>
> Modified patch attached.

Thanks! It looks good to me with one minor comment.

Is the following intended to remove "However"? It seems that we don't
need to modify the lines if the initial tip remains.

<para>
- However, if the default value is volatile (e.g.,
- <function>clock_timestamp()</function>)
+ If the default value is volatile (e.g.,
<function>clock_timestamp()</function>)
each row will need to be updated with the value calculated at the
time

Regards,
--
Masahiro Ikeda
NTT DATA CORPORATION