Server postgres_fdw "fetch_size" option cannot be updated

On Thu, Dec 28, 2017 at 12:33 PM, Logan Owen <pgsql@s1devops.com> wrote:

Hi everyone,

I'm playing around with postgres_fdw (version 1.0), and ran into an issue
where I wanted to update the "fetch_size" option on the server level:

sql> CREATE SERVER test_remote FOREIGN DATA WRAPPER postgres_fdw OPTIONS
(host 'postgres2', dbname 'test', updatable 'false')
[2017-12-28 10:30:13] completed in 35ms
sql> ALTER SERVER test_remote OPTIONS (set fetch_size '50')
[2017-12-28 10:30:26] [42704] ERROR: option "fetch_size" not found

However, I am able to properly set the "fetch_size" when originally
defining the server:

sql> CREATE SERVER test_remote2 FOREIGN DATA WRAPPER postgres_fdw OPTIONS
(host 'postgres2', dbname 'test', updatable 'false', fetch_size '50')
[2017-12-28 10:31:26] completed in 24ms

You use 'set' only if a value already exists and you wish to change it.
Since no value exists (the default does not count), you just do

ALTER SERVER test_remote OPTIONS (fetch_size '50');

Yes, this is confusing. But it is also documented, and I think it is
required by the SQL/MED standard.

Cheers,

Jeff

On Thu, Dec 28, 2017, at 15:42, Jeff Janes wrote:

On Thu, Dec 28, 2017 at 12:33 PM, Logan Owen <pgsql@s1devops.com> wrote:

Hi everyone,

I'm playing around with postgres_fdw (version 1.0), and ran into an issue where I wanted to update the "fetch_size" option on the server level:

sql> CREATE SERVER test_remote FOREIGN DATA WRAPPER postgres_fdw OPTIONS (host 'postgres2', dbname 'test', updatable 'false')
[2017-12-28 10:30:13] completed in 35ms
sql> ALTER SERVER test_remote OPTIONS (set fetch_size '50')
[2017-12-28 10:30:26] [42704] ERROR: option "fetch_size" not found

However, I am able to properly set the "fetch_size" when originally defining the server:

sql> CREATE SERVER test_remote2 FOREIGN DATA WRAPPER postgres_fdw OPTIONS (host 'postgres2', dbname 'test', updatable 'false', fetch_size '50')
[2017-12-28 10:31:26] completed in 24ms

 
You use 'set' only if a value already exists and you wish to change it.  Since no value exists (the default does not count), you just do

ALTER SERVER test_remote OPTIONS (fetch_size '50');

Yes, this is confusing.  But it is also documented, and I think it is required by the SQL/MED standard.

Cheers,

Jeff

Hi Jeff,

Thank you for quick reply, and you are right, it is referenced in the documentation for ALTER SERVER (https://www.postgresql.org/docs/9.6/static/sql-alterserver.html):

Change options for the server. ADD, SET, and DROP specify the action to be performed. ADD is assumed if no operation is explicitly specified. Option names must be unique; names and values are also validated using the server's foreign-data wrapper library.

My apologies for not being more thorough before assuming an issue, and have a great day!
Logan