Thread: 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@oss.nttdata.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
On Mon, Jan 6, 2025 at 3:18 AM Masahiro Ikeda <ikedamsh@oss.nttdata.com> wrote: > > On 2025-01-03 01:25, Robert Treat wrote: > > On Tue, Dec 3, 2024 at 3:13 AM Masahiro Ikeda > > <ikedamsh@oss.nttdata.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 > Technically speaking, because we split the tip into two distinct paragraphs, use of the word however would be considered poor grammar, though I'll admit I only removed it because it felt superfluous. Robert Treat https://xzilla.net
On 2025-01-07 06:27, Robert Treat wrote: > On Mon, Jan 6, 2025 at 3:18 AM Masahiro Ikeda > <ikedamsh@oss.nttdata.com> wrote: >> >> On 2025-01-03 01:25, Robert Treat wrote: >> > On Tue, Dec 3, 2024 at 3:13 AM Masahiro Ikeda >> > <ikedamsh@oss.nttdata.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 >> > > Technically speaking, because we split the tip into two distinct > paragraphs, use of the word however would be considered poor grammar, > though I'll admit I only removed it because it felt superfluous. OK, thanks for your comments. Regards, -- Masahiro Ikeda NTT DATA CORPORATION