doc: Add example for how to set file_fdw column option

The documentation is pretty light on how to set column options
on foreign tables, and the file_fdw docs refer to COPY when
documenting force_null even though it's not used in the same
way. Add a small example to describe how to use it.

Reported-by: Boshomi Phenix 
Discussion: https://postgr.es/m/CAJVkCUparn4_Oarernm=U6LWVsTkecKcALHtwGr5M3qJRj_czw@mail.gmail.com

diff --git a/doc/src/sgml/file-fdw.sgml b/doc/src/sgml/file-fdw.sgml
index 56d696c323c3da2f40fe58b6292add7971574379..b7f64930f06f7c3abde62f83d882c82a5cd1f86b 100644 (file)
--- a/doc/src/sgml/file-fdw.sgml
+++ b/doc/src/sgml/file-fdw.sgml
@@ -279,4 +279,20 @@ OPTIONS ( filename 'log/pglog.csv', format 'csv' );
   
  
 
+ 
+  Create a Foreign Table with an option on a column
+  
+   To set the force_null option for a column, use the
+   OPTIONS keyword.
+  
+
+CREATE FOREIGN TABLE films (
+ code char(5) NOT NULL,
+ title text NOT NULL,
+ rating text OPTIONS (force_null 'true')
+) SERVER film_server
+OPTIONS ( filename 'films/db.csv', format 'csv' );
+
+ 
+