Ошибка соединения ora 12154 tns невозможно разрешить имя службы

First published on MSDN on Jun 30, 2010

This is one of the most common errors while creating linked server to Oracle database. Today I will discuss the reason for this error and possible resolutions.

Full error message:

OLE DB provider «MSDAORA» for linked server «LINKED_ORA» returned message «ORA-12154: TNS:could not resolve the connect identifier specified».

Msg 7303, Level 16, State 1, Line 1

Cannot initialize the data source object of OLE DB provider «MSDAORA» for linked server «LINKED_ORA».

First of all make sure you have reviewed the following Microsoft KB article that has a lot of good information on troubleshooting Oracle linked server issues.

How to set up and troubleshoot a linked server to an Oracle database in SQL Server

http://support.microsoft.com/kb/280106

Also make sure you have installed Oracle Client on the SQL server. If the SQL server is 64 bit then we need to install 64 bit Oracle provider. You can also create linked server using Oracle ODBC driver together with Microsoft OLE DB provider for ODBC. Once again on a 64 bit SQL server you need to install the

64-Bit OLEDB Provider for ODBC (MSDASQL)

and 64 bit Oracle ODBC drivers. However 64-Bit OLEDB Provider for ODBC (MSDASQL) is already there in Windows Vista/Windows Server 2008 and later OS.

This particular error message is a very general error message and can happen for quite a number of reasons. For general understanding of the error, you can review oracle documentation like this

http://ora-12154.ora-code.com/

In SQL Server Linked Server, it could indicate a few things (not limited to)–

1.       SQL Server (and oracle net libraries) is not able to get the TNS alias from tnsnames.ora file.

2.       Something is wrong with the way the alias is created in the tnsnames.ora file (incorrect syntax)

3.       TNS alias could not be resolved into a connect descriptor

Below is a list of things that you can try to resolve this issue.

1. Verify that the tnsnames.ora file has the alias and the service name that the customer is using.

TNS entry for the Oracle database

===========================

OracleDB_Dev =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = server01.mydomain.com)(PORT = 1521))

)

(CONNECT_DATA =

(SERVICE_NAME = OracleDB)

(SERVER = DEDICATED)

)

)

In the above tnsnames.ora file Alias = OracleDB_Dev

Service Name: OracleDB (Actual Oracle service name [instance name in SQL])

2.  Check the sqlnet.ora file under ‘Admin’ folder in Oracle home [Dir:appproduct11.1.0client_1networkadmin] and ensure that we have TNSNames in NAMES.DIRECTORY_PATH

NAMES.DIRECTORY_PATH= (TNSNAMES, ONAMES, HOSTNAME)

3. Verify if you can connect to Oracle from the SQL server machine using tools installed with Oracle Client [For example «SQL Developer» or “SQL Plus”] with the same user id/password or TNS alias.

5. Check if the environment variable ‘PATH’ has the path for tnsnames.ora file specified.

Sample Value of Environment Variable PATH:

E:appproduct11.1.0client_1bin

;C:Program FilesBusiness ObjectsCommon3.5binNOTES;C:Program FilesBusiness ObjectsCommon3.5binNOTESDATA;%Systemroot%Microsoft.NETFrameworkv1.1.4322;%SystemRoot%system32;%SystemRoot%;%SystemRoot%System32Wbem;C:Program FilesDellSysMgtomabin;C:Program FilesMicrosoft SQL Server80ToolsBINN;C:Program FilesCommon FilesMicrosoft Sharedweb server extensions60TEMPLATEADMIN1033;C:Program FilesMicrosoft SQL Server80ToolsBinn;C:Program FilesMicrosoft SQL Server90DTSBinn;C:Program FilesMicrosoft SQL Server90Toolsbinn;C:Program FilesMicrosoft SQL Server90ToolsBinnVSShellCommon7IDE;C:Program FilesMicrosoft Visual Studio 8Common7IDEPrivateAssemblies;C:Program FilesMicrosoft Network Monitor 3

Note: make sure that the path is a valid path and there is no space.

6. Check the value of the key  ”Oracle_Home” in the registry under  HKEY_LOCAL_MACHINESOFTWAREORACLEKEY_OraClient11g_home1  and verify that it has the right path for the Oracle home.

7.  Check for the registry key “TNS_ADMIN” at HKEY_LOCAL_MACHINESOFTWAREORACLE. If it exists then make sure it has the right value as “Dir:appproduct11.1.0client_1networkadmin”. If you don’t see the key then create the key and set appropriate value as below.

Regedit->HKEY_LOCAL_MACHINE->Software->Oracle->RightClick NEW->StringValue and name

it TNS_ADMIN and give the value  “X:appproduct11.1.0client_1networkadmin”

Note: This is not a must but in some cases this is what fixed the issue.

8.   Check if SQL server start up account has permission to the Oracle Home. Also collect Process monitor log and check for “access denied”.  Process monitor log should show if we are able to find the tnsnames.ora file.

9. Make sure you don’t have multiple Oracle homes or multiple Oracle clients installed. Check the «HKEY_LOCAL_MACHINESOFTWAREORACLEALL_HOMESHOME_COUNTER» key value.

10. Check if Oracle OLE DB provider is running InProcess. If ‘yes’ then try to run out-of- process and see if that resolves the issue.

Note: You can check and verify if MS OLE DB Provider for Oracle is running InProcess from the registry key at HKEY_LOCAL_MACHINESOFTWAREMicrosoftMSSQLServerProvidersMSDAORA

11. You can try collecting simultaneous Network trace from both SQL and Oracle servers and check if there are any communications between the two servers.

12. Try to connect to Oracle from the SQL server using the UDL.  Use the same TNS name. If you get the same error that means the issue is not specific to SSMS or linked server.

Creating and Configuring Universal Data Link (.udl) Files

http://msdn.microsoft.com/en-us/library/e38h511e(VS.71).aspx

13.  Try to specify all the information in the data source instead of using the TNS alias to connect to the Oracle database (this is a way to bypass tnsnames.ora file when connecting to Oracle).

Sample Data Source:

Data Source=(DESCRIPTION=(CID=GTU_APP)(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST= server01.mydomain.com)(PORT=1521)))(CONNECT_DATA=(SID=OracleDB)(SERVER=DEDICATED)));

Author : Mohammad(MSFT) SQL Developer Engineer, Microsoft

Reviewed by : Azim(MSFT), SQL Developer Technical Lead , Microsoft

Arrhhh!! I RAN INTO THIS AGAIN!!!

Just install ToadForOracle in C: or any directory without parenthesis in the path.

In my case its because I was on a x64 PC and still using the old Oracle 9i with the 32bit drivers!

I am using SQL Reporting Services with an Oracle Database. The problem is the brackets in the path to Visual Studio (BIDS). Oracle doesn’t like apps that start in a path with brackets:

RDBMS 10g XE problem with parenthesis in path

So I made a BAT file to open Visual Studio with Progra~2 as the short path name for «Program Files (x86)».

Here is the contents of the BAT file:

rem Progra~2 is short path name for "Program Files (x86)" and works around an Oracle client bug that doesn't like the ()'s in the path
start /B "C:Progra~2Microsoft Visual Studio 9.0Common7IDE" "C:Progra~2Microsoft Visual Studio 9.0Common7IDEdevenv.exe"

I name this BAT file StartBIDS.BAT and put it in the directory:

«C:Program FilesMicrosoft SQL ServerStart BIDS.bat»

Then I make a short cut to the BAT file on my Desktop and also my Start Menu and change the ShortCuts icon. This allows me to open TOAD, Visual Studio, BIDS and etc apps that I use to work with Oracle.

Update:

Alternatively make a Junction:

mklink /J "C:Program Files (x86)" "C:Program Files x86"

Then remove the brackets in the shortcut:

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ORA-12154: TNS:could not resolve the connect identifier specified

This error means one thing, and one thing only. The client could not find the specified entry in the tnsnames.ora file being used.

As a follow-on to that statement, remember that when you use a dblink, the database in which the link is defined is acting as a client to the database that is the target of the link. So in this case, the tnsnames.ora file on the host of your source should have an entry for your target db, as defined in the db_link.

And for the umpteenth time … this error has nothing to do with the status of a listener. The connection request never got far enough to reach a listener. If anyone tells you to check a listener, they are not paying attention, or do not understand how TNS works. This error is the equivelent of not being able to place a telephone call because you don’t know the number of the party you want to reach. You wouldn’t debug that situation by going to the other guy’s house and testing his telephone, or by going to the phone company and testing the switchboard. And you don’t debug a ORA-12154 by checking the listener. If I had a top ten list of «Incredibly Simple Concepts ™» that should be burned into the brain of everyone who claims to be an Oracle DBA, it would include «ORA-12154 Has Nothing To Do With The Listener».

=====================================

Assume you have the following in your tnsnames.ora:

larry =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = curley)
    )
  )

Now, when you issue a connect, say like this:

$> sqlplus scott/[email protected]

tns will look in your tnsnames.ora for an entry called ‘larry’. Next, tns sends a request to (PORT = 1521) on (HOST = myhost) using (PROTOCOL = TCP), asking for a connection to (SERVICE_NAME = curley).

Where is (HOST = myhost) on the network? When the request gets passed from tns to the next layer in the network stack, the name ‘myhost’ will get resolved to an IP address, either via a local ‘hosts’ file, via DNS, or possibly other less used mechanisms. You can also hard-code the ip address (HOST = 123.456.789.101) in the tnsnames.ora.

Next, the request arrives at port 1521 on myhost. Hopefully, there is a listener on myhost configured to listen on port 1521, and that listener knows about SERVICE_NAME = curley. If so, you’ll be connected.

A couple of important points.

First, the listener is a server side only process. It’s entire purpose in life is the receive requests for connections to databases and set up those connections. Once the connection is established, the listener is out of the picture. It creates the connection. It doesn’t sustain the connection. One listener, running from one oracle home, listening on a single port, will serve multiple database instances of multiple versions running from multiple homes. It is an unnecessary complexity to try to have multiple listeners. That would be like the telephone company building a separate switchboard for each customer.

Second, the tnsnames.ora file is a client side issue. It’s purpose is for addressess resolution — the tns equivelent of the ‘hosts’ file further down the network stack. The only reason it exists on a host machine is because that machine can also run client processes.

What can go wrong?

First, there may not be an entry for ‘larry’ in your tnsnames. In that case you get «ORA-12154: TNS:could not resolve the connect identifier specified» No need to go looking for a problem on the host, with the listener, etc. If you can’t place a telephone call because you don’t know the number (can’t find your telephone directory (tnsnames.ora) or can’t find the party you are looking for listed in it (no entry for larry)) you don’t look for problems at the telephone switchboard.

Maybe the entry for larry was found, but myhost couldn’t be resolved to an IP address (say there was no entry for myhost in the local hosts file). This will result in «ORA-12545: Connect failed because target host or object does not exist»

Maybe there was an entry for myserver in the local hosts file, but it specified a bad IP address. This will result in «ORA-12545: Connect failed because target host or object does not exist»

Maybe the IP was good, but there is no listener running: «ORA-12541: TNS:no listener»

Maybe the IP was good, there is a listener at myhost, but it is listening on a different port. «ORA-12560: TNS:protocol adapter error»

Maybe the IP was good, there is a listener at myhost, it is listening on the specified port, but doesn’t know about SERVICE_NAME = curley. «ORA-12514: TNS:listener does not currently know of service requested in connect descriptor»

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