There's still something wrong with the way subtransactions are handled.
I got:
postgres=# SELECT * FROM foo;
ERROR: could not access status of transaction 118649
DETAIL: Could not open file "pg_subtrans/0001": No such file or directory.
in the standby after some testing.
I created a lot of subtransactions in the master, each inserting a row
to table 'foo', and left the transaction open. In another session, I did
a lot of dummy activity (truncate bar; insert into bar ...) to generate
WAL, and also checkpoints and pg_xlog_switch() calls. I then restarted
the standby, and got the above error.
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com