At Fri, 31 Mar 2017 12:32:39 +0900, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp> wrote in <f14ace82-d77e-f1fd-e313-f07df2c10...@lab.ntt.co.jp> > On 2017/03/31 8:28, David Rowley wrote: .. > > create server test_server foreign data wrapper postgres_fdw options > > (host 'localhost', port '5432', dbname 'postgres'); > > create foreign table ft_t (a int,b int) server test_server; ... > > select count(*) from pg_stat_Activity; -- > 6 > > analyze ft_t; > > ERROR: could not connect to server "test_server" > > DETAIL: FATAL: sorry, too many clients already > > CONTEXT: Remote SQL command: DECLARE c1 CURSOR FOR SELECT a, b FROM > > public.ft_t > > Remote SQL command: SELECT a, b FROM public.ft_t > > Remote SQL command: SELECT a, b FROM public.ft_t > > Remote SQL command: SELECT a, b FROM public.ft_t > > (lots of these) ... > IIUC, I think the cause would be that since the foreign table ft_t is > considered to be still foreign on the foreign server, which is > actually the same server, postgres_fdw recursively repeats the > loopback access to ft_t. (So, the same thing would happen for > something like: select * from ft_t.) If the analysis is right, ISTM > that it's the user's fault.
Agreed, this behavior is mentioned here. https://www.postgresql.org/docs/9.6/static/postgres-fdw.html#AEN182920 | table_name | | This option, which can be specified for a foreign table, gives | the table name to use for the foreign table on the remote | server. If this option is omitted, the foreign table's name is | used. regards, -- Kyotaro Horiguchi NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers