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Oracle Subscribers

Beginning with SQL Server 2005, SQL Server supports push subscriptions to Oracle through the Oracle OLE DB provider supplied by Oracle.

To configure an Oracle Subscriber, follow these steps:

  1. Install and configure Oracle client networking software and the Oracle OLE DB provider on the SQL Server Distributor, so that the Distributor can make connections to the Oracle Subscriber. The Oracle client networking software should be the most recent version available. Oracle recommends that users install the most recent versions of client software. The client software is therefore often a more recent version than the database software. The most straightforward way to install the software is to use the Oracle Universal Installer on the Oracle Client disk. In the Oracle Universal Installer, you will supply the following information:

    Information

    Description

    Oracle Home

    This is the path to the install directory for the Oracle software. Accept the default (C:\oracle\ora90 or similar) or enter another path. For more information about the Oracle Home, see the section "Considerations for Oracle Home" later in this topic.

    Oracle home name

    An alias for the Oracle home path.

    Installation type

    In Oracle 10g, select the Runtime or Administrator installation option.

  2. Create a TNS name for the Subscriber. TNS (Transparent Network Substrate) is a communication layer used by Oracle databases. The TNS Service Name is the name by which an Oracle database instance is known on a network. You assign a TNS Service Name when you configure connectivity to the Oracle database. Replication uses the TNS Service name to identify the Subscriber and to establish connections.

    After the Oracle Universal Installer is complete, use the Net Configuration Assistant to configure network connectivity. You must supply four pieces of information to configure network connectivity. The Oracle database administrator configures the network configuration when setting up the database and listener and should be able to provide this information if you do not have it. You must do the following:

    Action

    Description

    Identify the database

    There are two methods for identifying the database. The first method uses the Oracle System Identifier (SID) and is available in every Oracle release. The second method uses the Service Name, which is available starting with Oracle release 8.0. Both methods use a value that is configured when the database is created and it is important that the client networking configuration use the same naming method that the administrator used when configuring the listener for the database.

    Identify a network alias for the database

    You must specify a network alias, which is used to access the Oracle database. The network alias is essentially a pointer to the remote SID or Service Name that was configured when the database was created; it has been referred to by several names in different Oracle releases and products, including Net Service Name and TNS Alias. SQL*Plus prompts for this alias as the "Host String" parameter when you log in.

    Select the network protocol

    Select the appropriate protocols you would like to support. Most applications use TCP.

    Specify the host information to identify the database listener

    The host is the name or DNS alias of the computer on which the Oracle listener is running, which is typically the same computer on which the database resides. For some protocols, you must provide additional information. For example, if you select TCP, you must supply the port on which the listener is listening for connection requests to the target database. The default TCP configuration uses port 1521.

  3. Create a snapshot or transactional publication, enable it for non-SQL Server Subscribers, and then create a push subscription for the Subscriber. For more information, see Create a Subscription for a Non-SQL Server Subscriber.

Setting directory permissions

The account under which the SQL Server service on the Distributor runs must be granted read and execute permissions for the directory (and all subdirectories) where the Oracle client networking software is installed.

Testing connectivity between the SQL Server Distributor and the Oracle Publisher

Near the end of the Net Configuration Assistant there might be an option to test the connection to the Oracle Subscriber. Before you test the connection, ensure that the Oracle database instance is online and that the Oracle Listener is running. If the test is unsuccessful, contact the Oracle DBA responsible for the database to which you are trying to connect.

After you have made a successful connection to the Oracle Subscriber, attempt to log in to the database using the same account and password as you configured for the Distribution Agent for the subscription:

  1. Click Start, and then click Run.

  2. Type cmd and click OK.

  3. At the command prompt, type:

    sqlplus <UserSchemaLogin>/<UserSchemaPassword>@<NetServiceName>

    For example: sqlplus replication/$tr0ngPasswerd@Oracle90Server

  4. If the networking configuration was successful, the login will succeed and you will see a SQL prompt.

Considerations for Oracle Home

Oracle supports side-by-side installation of application binaries, but only one set of binaries can be used by replication at a given time. Each set of binaries is associated with an Oracle Home; the binaries are in the directory %ORACLE_HOME%\bin. You must ensure that the correct set of binaries (specifically the latest version of the client networking software) is used when replication makes connections to the Oracle Subscriber.

Log into the Distributor with the accounts used by the SQL Server service and the SQL Server Agent service and set the appropriate environment variables. The %ORACLE_HOME% variable should be set to refer to the installation point you specified when you installed the client networking software. The %PATH% must include the %ORACLE_HOME% \bin directory as the first Oracle entry that is encountered. For information about setting environment variables, see the Windows documentation.

Note Note

If you have more than one Oracle home on the SQL Server Distributor, ensure that the Distribution Agent is using the most recent Oracle OLE DB provider. In some cases, Oracle does not update the OLE DB provider by default when you update the client components on the SQL Server Distributor. Uninstall the old OLE DB provider and install the latest OLE DB provider. For more information about installing and uninstalling the provider, see the Oracle documentation.

In addition to the considerations covered in the topic Non-SQL Server Subscribers, consider the following issues when replicating to Oracle Subscribers:

  • Oracle treats both empty strings and NULL values as NULL. This is important if you define a SQL Server column as NOT NULL, and are replicating the column to an Oracle Subscriber. To avoid failures when applying changes to the Oracle Subscriber, you must do one of the following:

    • Ensure that empty strings are not inserted into the published table as column values.

    • Use the –SkipErrors parameter for the Distribution Agent if it is acceptable to be notified of failures in the Distribution Agent history log and to continue processing. Specify the Oracle error code 1400 (-SkipErrors 1400).

    • Modify the generated create table script, removing the NOT NULL attribute from any character columns that may have associated empty strings, and supply the modified script as a custom create script for the article using the @creation_script parameter of sp_addarticle.

  • Oracle Subscribers support a schema option of 0x4071. For more information about schema options, see sp_addarticle (Transact-SQL).

The following table shows the data type mappings that are used when data is replicated to a Subscriber running Oracle.

SQL Server data type

Oracle Data type

bigint

NUMBER(19,0)

binary(1-2000)

RAW(1-2000)

binary(2001-8000)

BLOB

bit

NUMBER(1)

char(1-2000)

CHAR(1-2000)

char(2001-4000)

VARCHAR2(2001-4000)

char(4001-8000)

CLOB

date

DATE

datetime

DATE

datetime2(0-7)

TIMESTAMP(7) for Oracle 9 and Oracle 10; VARCHAR(27) for Oracle 8

datetimeoffset(0-7)

TIMESTAMP(7) WITH TIME ZONE for Oracle 9 and Oracle 10; VARCHAR(34) for Oracle 8

decimal(1-38, 0-38)

NUMBER(1-38, 0-38)

float(53)

FLOAT

float

FLOAT

geography

BLOB

geometry

BLOB

hierarchyid

BLOB

image

BLOB

int

NUMBER(10,0)

money

NUMBER(19,4)

nchar(1-1000)

CHAR(1-1000)

nchar(1001-4000)

NCLOB

ntext

NCLOB

numeric(1-38, 0-38)

NUMBER(1-38, 0-38)

nvarchar(1-1000)

VARCHAR2(1-2000)

nvarchar(1001-4000)

NCLOB

nvarchar(max)

NCLOB

real

REAL

smalldatetime

DATE

smallint

NUMBER(5,0)

smallmoney

NUMBER(10,4)

sql_variant

N/A

sysname

VARCHAR2(128)

text

CLOB

time(0-7)

VARCHAR(16)

timestamp

RAW(8)

tinyint

NUMBER(3,0)

uniqueidentifier

CHAR(38)

varbinary(1-2000)

RAW(1-2000)

varbinary(2001-8000)

BLOB

varchar(1-4000)

VARCHAR2(1-4000)

varchar(4001-8000)

CLOB

varbinary(max)

BLOB

varchar(max)

CLOB

xml

NCLOB

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