[GENERAL] UDF calls and FDW

[Emmanuel Medernach]

Hello,

I am using FDW to transparently access a remote Postgres database
containing a table indexed with the Q3C library.
On the remote server :

  postgres=# SELECT * FROM object_000 WHERE q3c_radial_query(ra_PS, decl_PS, 
1.3, 3.4, .2) ;
  ...
  (2416 rows)

  Time: 130.300 ms

But on the FDW node the timing is bad :

  postgres=# SELECT * FROM master_object_000 WHERE q3c_radial_query(ra_PS, 
decl_PS, 1.3, 3.4, .2) ;
  ...
  (2416 rows)

  Time: 130843.931 ms

postgres=# explain SELECT * FROM master_object_000 WHERE q3c_radial_query(ra_PS, 
decl_PS, 1.3, 3.4, .2) ;
                                                   QUERY PLAN 

-----------------------------------------------------------------------------------------------------------------
 Foreign Scan on master_object_000  (cost=100.00..383744.04 rows=377539 
width=1084)
   Filter: q3c_radial_query(ra_ps, decl_ps, 1.3::double precision, 3.4::double 
precision, 0.2::double precision)
(2 rows)


So the problem is that is  calls the UDF on the FDW node (Foreign
Scan on master_object_000 + Filter) and not on the remote server.

  - How to call the UDF on the remote server ?

Regards,
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