I have just discovered if you try to lo_import() an empty file, and oid
is returned, but nothing is added to pg_largeobject:
$ > /rtmp/a
$ psql test
SELECT lo_import('/rtmp/a');
lo_import
-----------
16385
SELECT * from pg_largeobject;
loid | pageno | data
------+--------+------
However, the oid is incremented for each call:
SELECT lo_import('/rtmp/a');
lo_import
-----------
16386
SELECT lo_import('/rtmp/a');
lo_import
-----------
16387
SELECT lo_import('/rtmp/a');
lo_import
-----------
16388
An lo_export() of a non-existant oid does create an empty file. I guess
this is an optimization of allowing empty file imports to consume no
space in pg_largeobject, but it does seem odd.
I am asking hackers in case someone can see an error here, or something
that should be documented.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +
