Re: Comparing two tables of different database

Hi All,

For example,

There are two database. database1 and database 2;

database1 has a table called pr_1 with the columns, id,name and time.
database2 has a table called sr_1 with the_columns id,name and time.

i would like to find out the differences that is, find the names that
are not in sr_1 but in pr_1.
we can achieve this by the query,

select name from sr_1 where name not in (select name from pr_1);
the above query will work in case of two tables in the same database.

But the problem is, these two tables are in different database. i did
not understand about the dblink.

is there any exaples on dblink. can we do it without using dblink.

-Nicholas I

On Thu, Apr 30, 2009 at 9:07 AM, Joshua Tolley <eggyknap(at)gmail(dot)com> wrote:

> On Thu, Apr 30, 2009 at 08:20:02AM +1000, Adam Ruth wrote:
> > The simple answer is to pg_dump both tables and compare the output
> with
> > diff.
> > Other than that, I think you'll need a custom program.
>
> For all but the strictest definition of "identical", that won't work.
> Tables may easily contain the same information, in different on-disk
> order, and pg_dump will most likely give the data to you in an order
> similar to its ordering on disk.
>
> Something like a COPY (<query>) TO <file>, where <query> includes an
> ORDER BY clause, might give you a suitable result from both tables, on
> which you could then take a checksum.
>
> - Josh / eggyknap
>
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.9 (GNU/Linux)
>
> iEYEARECAAYFAkn5HQoACgkQRiRfCGf1UMPcagCfQDRa2bXPRjgSuVsrFYTnGTTC
> rhoAnAlGwp0vSKd2uspyFvxCTfugG6Yh
> =LO6r
> -----END PGP SIGNATURE-----
>
>