Re: ALTER Table (another) - Mailing list pgsql-general

Quoting Andrew Ayers <aayers@eldocomp.com>:

> Shridhar Daithankar wrote:
> > Gaetano Mendola wrote:
> >
> >> Shridhar Daithankar wrote:
> >>
> >>> Alex wrote:
> >>>
> >>>> is it possible to add a column to a table at a specific place ?
> >>>> Reading the man pages i could not figure that out.
>
> [snip]
>
> On a similar note, it would be nice if you could do an ALTER TABLE to
> update the field definitions. Recently, I had the need to change the
> size of a VARCHAR field from 5 characters to 10 characters. This was due
> to a change in the underlying application, one that at the time of
> adding the field to the table was thought to be adequate - well, times
> and ideas change, users clamor for something different, etc...
>
> The only way to do what I needed done was to dump the table, drop it,
> alter the sql in the dump, then re-import it. While it didn't take long
> to do, it seemed like a big band-aid - something you should be able to
> do with an ALTER TABLE, but can't (I am currently using PG 7.3.2)...
>
> Is this something coming down the pipeline in the future?
>
> Andrew Ayers
> Phoenix, Arizona
>
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Andrew,

This was discussed on list a couple of months ago and I forget the outcome but I
think the gist of things what that there would be no **easy way** to maintain
ACID properties with this type of alter table function.

Though is would be fine to change a varchar 5 to 10 what about the person who
accidentally does the reverse?  Now consider the logic to would go to making
sure this type of operation would not lead to corruption.

I didn't get a chance to find and re-read the previous thread on this but based
on what I remember I'm pretty sure this alter table function is on the todo list
it just did't make it into 7.4.  If it is, its not in the dev docs
(http://developer.postgresql.org/docs/postgres/sql-altertable.html)

--
Keith C. Perry
Director of Networks & Applications
VCSN, Inc.
http://vcsn.com

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