On an Oracle Database instance, if I set:<\/p>\n
alter system set remote_listener='cluster-scan:1521';<\/pre>\nThe instance tries to resolve the cluster-scan name to detect if it is a SCAN address.
\nSo, after it solves, it stores all the addresses it gets and registers to them.
\nI can check which addresses there are with this query:<\/p>\nSQL> select type, value from v$listener_network where type='REMOTE LISTENER';\r\n\r\nTYPE VALUE\r\n---------------- ---------------------------------------------------------------------------------------------------\r\nREMOTE LISTENER (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=TCP)(HOST=10.0.0.1)(PORT=1521)))\r\nREMOTE LISTENER (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=TCP)(HOST=10.0.0.2)(PORT=1521)))\r\nREMOTE LISTENER (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=TCP)(HOST=10.0.0.3)(PORT=1521)))\r\n<\/pre>\nIn this case, the instance registers to the three addresses discovered, which is OK: all three SCAN listeners will get service updates from the instance.<\/p>\n
But if I have this TNS alias:<\/p>\n
REMOTE_LISTENER=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(PORT=1521)(HOST=cluster-scan)))<\/pre>\nand I set:<\/p>\n
alter system set remote_listener='remote_listener';<\/pre>\nI get:<\/p>\n
SQL> select type, value from v$listener_network where type='REMOTE LISTENER';\r\n\r\nTYPE VALUE\r\n---------------- ---------------------------------------------------------------------------\r\nREMOTE LISTENER (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(PORT=1521)(HOST=cluster-scan)))\r\n<\/pre>\nthe result is that the instance registers only at the first IP fot from the DNS, leaving the other SCANs without the service registration and thus random<\/p>\n
ORA-12514, TNS:listener does not currently know of service requested in connect descriptor<\/pre>\nThis is in my opinion quite annoying, as my goal here was to have all the DBs set with:<\/p>\n
local_listener=local_listener\r\nremote_listener=remote_listener<\/pre>\nin order to facilitate changes of ports, database migrations from different clusters, clones, etc.<\/p>\n
So the solution is either to revert to the syntax “cluster-scan:port”, or specifying explicitly all the endpoints in the address list:<\/p>\n
REMOTE_LISTENER = (DESCRIPTION= (ADDRESS_LIST=\r\n (ADDRESS= (PROTOCOL=TCP) (PORT=1521) (HOST=10.0.0.1))\r\n (ADDRESS= (PROTOCOL=TCP) (PORT=1521) (HOST=10.0.0.2))\r\n (ADDRESS= (PROTOCOL=TCP) (PORT=1521) (HOST=10.0.0.3))\r\n ))<\/pre>\nI am sure it is “working as designed”, but I wonder if it could be an enhancement to have the address expended fully also in case of TNS alias….
\nOr… do you know any way to do it from a TNS alias without having the full IP list?<\/p>\nCheers<\/p>\n
—<\/p>\n
Ludo<\/p>\n","protected":false},"excerpt":{"rendered":"
On an Oracle Database instance, if I set: alter system set remote_listener=’cluster-scan:1521′; The instance tries to resolve the cluster-scan name to detect if it is a SCAN address. So, after it solves, it stores all the addresses it gets and … Continue reading