Re: Easiest way to compare the results of two queries row by row and column by column

On Thu, Jun 20, 2013 at 3:18 PM, Jason Long
<mailing(dot)lists(at)octgsoftware(dot)com>wrote:

> Can someone suggest the easiest way to compare the results from two
> queries to make sure they are identical?
>
> I am rewriting a large number of views and I want to make sure that
> nothing is changes in the results.
>
> Something like
>
> select compare_results('select * from v_old', 'select * from v_new');
>

I'd run:

select * from v_old
except
select * from v_new ;

And then

select * from v_new
except
select * from v_old ;

Both should return no rows.

However, if the queries can contain duplicate rows this will not detect
differences in the number of times a row is replicated, i.e. if one query
has a row 2 times and the other has it 3 times. If you need to detect such
cases, I'd probably \copy out each query to a file, then use system tools
to sort and diff the files.

Cheers,

Jeff