Re: Foreign Data Wrapper Handler

On 11/8/20 11:09 AM, Susan Hurst wrote:
> The first pass thru https://www.postgresql.org/docs/12/fdwhandler.html
> does not tell me what I think I need to know, but I will digest this
> more thoroughly. Maybe I need to understand more of the lingo re:
> foreign data wrappers. I do understand that all fdw names must be unique
> within a database so if I want to connect to more than one foreign db, I
> need a different name for each connection. I cannot name each fdw
> postgres_fdw. I would like to name the fdws something like:
> dbname_to_foreigndbname.
>
> For example, here are 2 possible fdws:
>
> create foreign data wrapper stp_to_geo;
> create foreign data wrapper stp_to_metrics;

Aren't you looking for?:

https://www.postgresql.org/docs/12/sql-createserver.html

"
A foreign server typically encapsulates connection information that a
foreign-data wrapper uses to access an external data resource.
Additional user-specific connection information may be specified by
means of user mappings.

The server name must be unique within the database.
"

>
> That syntax creates the fdw and I can create user mappings but I cannot
> import any foreign schemas into my database. The error message says that
> there is no handler for the fdw. That's where I'm stuck.
>
> BTW, I did try using postgres_fdw as a handler...
>
> create foreign data wrapper stp_to_geo handler postgres_fdw;
>
> ...but then I got these errors:
> ERROR:  function postgres_fdw() does not exist
> ERROR:  foreign-data wrapper "stp_to_geo" does not exist
>
> Looks like I need to study a bit more.
>
> Sue
>
>
> ---
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Susan E Hurst
> Principal Consultant
> Brookhurst Data LLC
> Email: susan(dot)hurst(at)brookhurstdata(dot)com
> Mobile: 314-486-3261
>
> On 2020-11-07 14:51, Adrian Klaver wrote:
>> On 11/7/20 12:44 PM, Susan Hurst wrote:
>>> Can anyone recommend a good online resource for learning how to set
>>> up a foreign data wrapper using a custom fdw name?  It seems the
>>> trick is to use a handler to make it work but so far the search
>>> results have been elusive for creating a fdw with a successful outcome.
>>
>> Have you gone through this?:
>>
>> https://www.postgresql.org/docs/12/fdwhandler.html
>>
>> Also can we get a definition of 'custom fdw name'?
>>
>>
>>>
>>> I'm using 'PostgreSQL 11.8 on amd64-portbld-freebsd12.1, compiled by
>>> FreeBSD clang version 8.0.1 (tags/RELEASE_801/final 366581) (based on
>>> LLVM 8.0.1), 64-bit'
>>>
>>> Thanks for your help!
>>>
>>> Sue
>>>
>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com