Takahiro Itagaki wrote: > KaiGai Kohei <kai...@ak.jp.nec.com> wrote: > >> The attached patch fixes these matters. > > I'll start to check it.
Thanks, >> We have to reference pg_largeobject_metadata to check whether a certain >> large objct exists, or not. > > What is the situation where there is a row in pg_largeobject_metadata > and no corresponding rows in pg_largeobject? Do we have a method to > delete all rows in pg_largeobject but leave some metadata? It is a case when we create a new large object, but write nothing. postgres=# SELECT lo_create(1234); lo_create ----------- 1234 (1 row) postgres=# SELECT * FROM pg_largeobject_metadata WHERE oid = 1234; lomowner | lomacl ----------+-------- 10 | (1 row) postgres=# SELECT * FROM pg_largeobject WHERE loid = 1234; loid | pageno | data ------+--------+------ (0 rows) In this case, the following two queries are not equivalent. * SELECT oid FROM pg_largeobject_metadata * SELECT DISTINCT loid FROM pg_largeobject The second query does not return the loid of empty large objects. The prior implementation inserted a zero-length page to show here is a large object with this loid, but it got unnecessary with this enhancement. If we need compatibility in this level, we can insert a zero-length page into pg_largeobject on LargeObjectCreate(). It is harmless, but its worth is uncertain. Thanks, -- OSS Platform Development Division, NEC KaiGai Kohei <kai...@ak.jp.nec.com> -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers