Hi , Today i have faced this issue while configuring the Slony on Ubuntu.. FATAL localListenThread: "select "".cleanupNodelock(); insert into "_rep".sl_nodelock values ( 1, 0, "pg_catalog".pg_backend_pid()); " - ERROR: duplicate key value violates unique constraint "sl_nodelock-pkey" DETAIL: Key (nl_nodeid, nl_conncnt)=(1, 0) already exists After analyzing this "cleanupnodelock" function, slon deamon could not able to delete this entry from the table due to some reasons. Find the below entry . master=# select * from _rep.sl_nodelock; nl_nodeid | nl_conncnt | nl_backendpid -----------+------------+--------------- 1 | 0 | 22988 So, i have removed it manually and started the deamons successfully... master=# delete from _rep.sl_nodelock ; DELETE 1 However, it works for me successfully. And my primary and slave are in sync after this hack ..:) --Dinesh