Ordering of results in query templates involving UNION

Hi,

I was trying out the beta download and noticed that the SQL definition for
some of my constraints had the columns in the wrong order. I traced this
to
https://git.postgresql.org/gitweb/?p=pgadmin4.git;a=blob;f=web/pgadmin/browser/server_groups/servers/databases/schemas/tables/templates/index_constraint/sql/get_constraint_cols.sql;hb=702609517f23be7c14e2f9d655f66ea8ac43dd9c
which has the form of a SELECT ... UNION SELECT ... for each column in the
constraint. I was able to fix this one case by appending the loop index as
a new column and ordering by that:

{% for n in range(colcnt|int) %}
{% if loop.index != 1 %}
UNION SELECT pg_get_indexdef({{ cid|string }}, {{ loop.index|string
}}, true) AS column, {{ loop.index|string }} AS idx
{% else %}
SELECT pg_get_indexdef({{ cid|string }} , {{ loop.index|string }} ,
true) AS column, {{ loop.index|string }} AS idx
{% endif %}
{% endfor %}
ORDER BY idx

There are a few other templates where it looks like the same pattern
happens. In a lot of them you use UNION ALL, which may coincidentally
return rows the same order as the individual SELECT statements. In the one
above you use UNION so hashing is used and rows are returned in a less
predictable order. I think that even in the first case an ORDER BY clause
is required for correctness -- or the rows need to be sorted in the client
code before generating the SQL.

I have not attached a patch as I've not been involved on pgAdmin
development. But if the problem and the fix makes sense I would be happy
to work on one to try to add ordering to UNION-based query templates (e.g.
the ones on this list
https://git.postgresql.org/gitweb/?p=pgadmin4.git&a=search&h=HEAD&st=grep&s=UNION
).

Cheers,
Edmund Horner