Thread: lo_import() of an empty file
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 +
Bruce Momjian <bruce@momjian.us> writes: > I have just discovered if you try to lo_import() an empty file, and oid > is returned, but nothing is added to pg_largeobject: Why would you expect there to be? There's no data to store. There should be an entry in pg_largeobject_metadata, though. regards, tom lane
On Fri, Mar 30, 2018 at 02:22:49PM -0400, Tom Lane wrote: > Bruce Momjian <bruce@momjian.us> writes: > > I have just discovered if you try to lo_import() an empty file, and oid > > is returned, but nothing is added to pg_largeobject: > > Why would you expect there to be? There's no data to store. > > There should be an entry in pg_largeobject_metadata, though. Ah, yes, there is a row there. Thanks. No problem here. -- 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 +