Re: Why is there no object create date is the catalogs? - Mailing list pgsql-general

On 05/12/2015 03:44 PM, Melvin Davidson wrote:
> Adrian,
>
> You are over thinking this. An object is only "created" once! That is
> what I meant by relcreatedate. If it is dropped, then it is deleted from
> the catalogs. If it is modified, then it does NOT affect the creation
> date. Everything else is superfluous.

See my original post and Tom Lanes response.

>
> It is also not unusual for tables to have an end of cycle in certain
> application, hence the need to be dropped after a certain time. EG.
> Tables that track data only for a specific year.

Hence my link to the partitioning part of the manual.

>
> Since PostgreSQL already tracks when tables are vacuum, auto vacuumed,
> analyzed and auto analyzed ( pg_stat_all_tables ), I don't see why it is
> such a big deal ( or so hard ) to track when an object is created. It
> should be a very simple patch to the catalogs.

It is probably not a big deal to create a timestamp field and populate
it. The issues arise when you start asking what it really means. The
Postgres catalogs are not part of dump file, so the data in them will
not transfer when you restore to another database. So on restore the
create date will be the date the table is restored, not the date the
table was originally created. For some people that is okay, for others
not okay.

>
> On Tue, May 12, 2015 at 6:00 PM, Adrian Klaver
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> wrote:
>
>     On 05/12/2015 12:51 PM, Melvin Davidson wrote:
>
>
>         Can anyone tell me why there is no "relcreated" column in
>         pg_class to
>         track the creation date of an object?
>
>
>     Meant to add to my previous post, back before I 'discovered' version
>     control I use to put the creation date in the table COMMENT:
>
>     http://www.postgresql.org/docs/9.4/interactive/sql-comment.html
>
>
>         It seems to me it would make sense to have one as it would
>         facilitate
>         auditing of when objects are created. In addition, it would also
>         facilitate the dropping of objects that have exceeded a certain age.
>
>         EG: SELECT 'DELETE TABLE ' || relname || ';'
>                 FROM pg_class
>                WHERE relkind = 'r'
>                  AND relcreated > current_timestamp - INTERVAL ' 1 year';
>
>         Adding that column should be relatively easy and would not break
>         backwards compatiblity with previous versions.
>         --
>         *Melvin Davidson*
>
>
>
>     --
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
>
>
>
>
> --
> *Melvin Davidson*
> I reserve the right to fantasize.  Whether or not you
> wish to share my fantasy is entirely up to you.


--
Adrian Klaver
adrian.klaver@aklaver.com