Hi,<br /><br />maybe this is a better group for this question?<br /><br />I can't see why creating foreign key on table
Areferencing table B, generates an AccessExclusiveLock on B.<br />It seems (to a layman :-) ) that only writes to B
shouldbe blocked.<br /><br />I'm really interested if this is either expected effect or any open TODO item or
suboptimalbehavior of postgres.<br /><br />Thanks<br /><br /><br /><div class="gmail_quote">---------- Forwarded
message----------<br />From: <b class="gmail_sendername">Filip Rembiałkowski</b> <span dir="ltr"><<a
href="mailto:filip.rembialkowski@gmail.com">filip.rembialkowski@gmail.com</a>></span><br/> Date: Thu, Nov 1, 2012 at
5:33PM<br />Subject: question on foreign key lock<br />To: pgsql-general list <<a
href="mailto:pgsql-general@postgresql.org">pgsql-general@postgresql.org</a>><br/><br /><br />Hello.<br /><br /> Why
addingFK creates AccessExclusiveLock on referenced tabble?<br /><br /> {{{<br /> CREATE TABLE A ( id integer, idb
integer);<br /> INSERT INTO A (id,idb) SELECT x, x%4 FROM generate_series(1,100) x;<br /><br /> CREATE TABLE B ( id int
primarykey );<br /> INSERT INTO B VALUES (0),(1),(2),(3);<br /><br /> BEGIN;<br /> ALTER TABLE A ADD CONSTRAINT
a_idb_fkeyFOREIGN KEY (idb) REFERENCES b;<br /> SELECT * FROM pg_locks l, pg_class c WHERE l.pid = pg_backend_pid() AND
l.locktype='relation'AND l.mode ilike '%exclusive%' AND l.relation=c.oid;<br /> ROLLBACK;<br /> }}}<br /><br /><br />
LastSELECT is showing AccessExclusive on B.<br /> Why not Exclusive?<br /><br /><br /> Thanks,<br /> Filip<br
/></div><br/>
