Horton

Re: file_fdw vs relative paths

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Magnus Hagander <magnus@hagander.net>
Cc: PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2020-08-25T00:26:12Z
Lists: pgsql-hackers

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On Wed, Jul 15, 2020 at 01:22:21PM +0200, Magnus Hagander wrote:
> According to the documentation, the filename given in file_fdw must be an
> absolute path. Hwever, it works perfectly fine with a relative path.
> 
> So either the documentation is wrong, or the code is wrong. It behaves the same
> at least back to 9.5, I did not try it further back than that.

Yes, I tested back to 9.5 too:

	CREATE EXTENSION file_fdw;
	CREATE SERVER pgconf FOREIGN DATA WRAPPER file_fdw;
	CREATE FOREIGN TABLE pgconf (line TEXT) SERVER pgconf OPTIONS ( filename
		'postgresql.conf', format 'text', delimiter E'\x7f' );
	SELECT * FROM pgconf;
	 # -----------------------------
	 # PostgreSQL configuration file
	 # -----------------------------
	 #
	 # This file consists of lines of the form:
	...

> I can't find a reference to the code that limits this. AFAICT the documentation
> has been there since day 1.
> 
> Question is, which one is right. Is there a reason we'd want to restrict it to
> absolute pathnames?

I think it should work just like COPY, which allows relative paths;  doc
patch attached.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee

Commits

  1. Change path in example of file_fdw for logs

  2. Fix docs bug stating file_fdw requires absolute paths

  3. Add contrib/file_fdw foreign-data wrapper for reading files via COPY.