Re: dblink: add polymorphic functions.

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On 07/29/2015 09:40 AM, Corey Huinker wrote:
> Say I've got a table my_partitioned_table (key1 integer, key2
> integer, metric1 integer, metric2 integer);
>
> And I've got many partitions on that table. My code lets you do
> something like this:
>
> select key1, key2, sum(metric1) as a_sum_of_sums, sum(metric2) as
> another_sum_of_sums from
> execute_buncha_queries(null::my_partitioned_table,
> 'connection_string_thats_just_a_loopback', array['select key1,
> key2, sum(metric1), sum(metric2) from my_partition_p1 group by
> 1,2', 'select key1, key2, sum(metric1), sum(metric2) from
> my_partition_p2 group by 1,2', ...]) group by 1,2

> I can't put a cast around execute_buncha_queries because the
> function won't know how to cast the results coming back from
> dblink.

Ok, gotcha. So Tom's nearby comment about allowing the
"p_rowtype%TYPE" syntax to be used in the CAST is spot on (as usual).
In other words, to get a complete solution for you we would need to
make both things work, so you could do this inside plpgsql:

select * from cast(dblink(connstr, sql) as p_rowtype%TYPE);

where potentially connstr, sql, p_rowtype are all passed to plpgsql as
arguments. Correct?

Joe

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