Re: [PATCH] Do not flush BufFile for regular temp files

Hello

I think there is an issue with this patch: you are not taking into account a inter-transaction BufFile.

If a BufFile is created with isInterXact set to true, BufFileClose does not flush data and this looks wrong.

You can test this with the following extension https://github.com/pierreforstmann/buffile .

With PostgreSQL 20devdel, I get:
--
-- Test BufFileClose() flushing behavior.
--
CREATE EXTENSION buffile;
-- A regular temporary BufFile should not be flushed by BufFileClose().
--
-- With temp_file_limit = 0, a physical write must fail. Therefore
-- false means that BufFileClose() did not attempt the write.
SET temp_file_limit = 0;
SELECT test_buffile_temp(false);
INFO: BufFileClose has not flushed data
test_buffile_temp
-------------------
f
(1 row)

-- An inter-transaction BufFile must still be flushed by BufFileClose().
--
-- Therefore the physical write should fail with temp_file_limit = 0.
SELECT test_buffile_temp(true);
INFO: BufFileClose has not flushed data
test_buffile_temp
-------------------
f
(1 row)

RESET temp_file_limit;
-- A FileSet BufFile must also be flushed by BufFileClose(), because
-- another opener must be able to see its contents.
SELECT test_buffile_fileset();
INFO: BufFileClose has flushed data
test_buffile_fileset
----------------------
t
(1 row)

Regards
Pierre Forstmann