Re: Column reordering in pg_dump

On Fri, Nov 14, 2008 at 4:12 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "hernan gonzalez" <hgonzalez(at)gmail(dot)com> writes:
>> I've added an option to pg_dump to reorder
>> columns in the ouput "CREATE TABLE" dump.
>
> This doesn't seem like a particularly good idea to me. In the first
> place, pg_dump is a tool for reproducing your database, not altering it,
> so it seems like basically the wrong place to be inserting this type of
> feature. (There's been some talk of a Postgres ETL tool, which would be
> the right place, but so far it's only talk :-(.) In the second place,
> column order is actually a pretty delicate affair when you start to
> think about table inheritance situations and tables that have been
> altered via ADD/DROP COLUMN. We had bugs in pg_dump in the past with
> its ability to deal with column order in such cases. So I'm not nearly
> as optimistic as you are that such a feature is incapable of causing
> problems.
>
> regards, tom lane

> In the first placeplace, pg_dump is a tool for reproducing your database, not altering it

Yes, but the standard/recommended procedure for reorder columns in postgresql
is "pg_dump , edit , restore". I just didn't want to mess editing a dump.

Of couse, the standard behavior of pg_dump is not altered when the
"reorder" option
is not use. And bear in mind that the reordering hook is guaranteed to
alter only the order
of the "CREATE TABLE" fields. (The original and the modified dump
will differ only in that;
even in the case of dropped columns and inherited tables). The only
possible troubling scenario
I can imagine: a dump using a COPY without columns names in the data
dump; but that
only arises with version < 7.3.

Anyway, I know you know better.
Best regards!

Hernán J. González
http://hjg.com.ar/