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
