B Initialization Parameters

B.3.1 HS_CALL_NAME

Specifies the remote functions that can be referenced in SQL statements. The value is a list of remote functions and their owners, separated by semicolons, in the following format:

[owner_name.]function_name
 

For example:

owner1.A1;owner2.A2;A3 

If an owner name is not specified for a remote function, the default owner name becomes the user name used to connect to the remote database (specified when the Heterogeneous Services database link is created or taken from user session if not specified in the DB link).

The entries for the owner names and the function names are case-sensitive.

B.3.2 HS_DB_DOMAIN

Specifies a unique network sub-address for a non-Oracle system. The HS_DB_DOMAIN initialization parameter is similar to the DB_DOMAIN initialization parameter, described in the Oracle Database Reference. The HS_DB_DOMAIN initialization parameter is required if you use the Oracle Names server. The HS_DB_NAME and HS_DB_DOMAIN initialization parameters define the global name of the non-Oracle system.

B.3.3 HS_DB_INTERNAL_NAME

Specifies a unique hexadecimal number identifying the instance to which the Heterogeneous Services agent is connected. This parameter's value is used as part of a transaction ID when global name services are activated. Specifying a nonunique number can cause problems when two-phase commit recovery actions are necessary for a transaction.

B.3.4 HS_DB_NAME

Specifies a unique alphanumeric name for the data store given to the non-Oracle system. This name identifies the non-Oracle system within the cooperative server environment. The HS_DB_NAME and HS_DB_DOMAIN initialization parameters define the global name of the non-Oracle system.

B.3.5 HS_DESCRIBE_CACHE_HWM

Specifies the maximum number of entries in the describe cache used by Heterogeneous Services. This limit is known as the describe cache high water mark. The cache contains descriptions of the mapped tables that Heterogeneous Services reuses so that it does not have to re-access the non-Oracle data store.

If you are accessing many mapped tables, increase the high water mark to improve performance. Increasing the high water mark improves performance at the cost of memory usage.

B.3.6 HS_LANGUAGE

Provides Heterogeneous Services with character set, language, and territory information of the non-Oracle data source. The value must use the following format:

language[_territory.character_set]

B.3.7 HS_LONG_PIECE_TRANSFER_SIZE

Sets the size of the piece of LONG data being transferred. A smaller piece size means less memory requirement, but more round-trips to fetch all the data. A larger piece size means fewer round-trips, but more of a memory requirement to store the intermediate pieces internally. Thus, the initialization parameter can be used to tune a system for the best performance, with the best trade-off between round-trips and memory requirements, and network latency or response time.

B.3.8 HS_OPEN_CURSORS

Defines the maximum number of cursors that can be open on one connection to a non-Oracle system instance.

The value never exceeds the number of open cursors in the Oracle database. Therefore, setting the same value as the OPEN_CURSORS initialization parameter in the Oracle database is recommended.

B.3.9 HS_RPC_FETCH_REBLOCKING

Controls whether Heterogeneous Services attempts to optimize performance of data transfer between the Oracle database and the Heterogeneous Services agent connected to the non-Oracle data store.

The following values are possible:

• OFF disables reblocking of fetched data so that data is immediately sent from agent to server.

• ON enables reblocking, which means that data fetched from the non-Oracle system is buffered in the agent and is not sent to the Oracle database until the amount of fetched data is equal or higher than the value of HS_RPC_FETCH_SIZE initialization parameter. However, any buffered data is returned immediately when a fetch indicates that no more data exists or when the non-Oracle system reports an error.

B.3.10 HS_RPC_FETCH_SIZE

Tunes internal data buffering to optimize the data transfer rate between the server and the agent process.

Increasing the value can reduce the number of network round-trips needed to transfer a given amount of data, but also tends to increase data bandwidth and to reduce latency as measured between issuing a query and completion of all fetches for the query. Nevertheless, increasing the fetch size can increase latency for the initial fetch results of a query, because the first fetch results are not transmitted until additional data is available.

B.3.11 HS_TRANSACTION_MODEL

Specifies the type of transaction model that is used when the non-Oracle database is updated by a transaction.

The following values are possible:

• COMMIT_CONFIRM provides read and write access to the non-Oracle database and allows the gateway to be part of a distributed update. To use the commit-confirm model, the following items must be created in the non-Oracle database:

  • Transaction log table. The default table name is HS_TRANSACTION_LOG. A different name can be set using the HS_FDS_TRANSACTION_LOG parameter. The transaction log table must be granted SELECT, DELETE, and INSERT privileges set to public.

  • Recovery account. The account name is assigned with the HS_FDS_RECOVERY_ACCOUNT parameter.

  • Recovery account password. The password is assigned with the HS_FDS_RECOVERY_PWD parameter.

    COMMIT_CONFIRM does not apply to Oracle Database Gateway for ODBC. The default value for Oracle Database Gateway for ODBC is SINGLE_SITE.

• READ_ONLY provides read access to the non-Oracle database.

• READ_ONLY_AUTOCOMMIT provides read access to the non-Oracle database that do not have logging.

• SINGLE_SITE provides read and write access to the non-Oracle database. However, the gateway cannot participate in distributed updates.

• SINGLE_SITE_AUTOCOMMIT provides read and write access to the non-Oracle database that do not have logging. Any update is committed immediately, and the gateway cannot participate in distributed updates.

B.3.12 IFILE

Use the IFILE initialization parameter to embed another initialization file within the current initialization file. The value should be an absolute path and should not contain environment variables. The three levels of nesting limit do not apply.

B.3.13 HS_FDS_CONNECT_INFO

HS_FDS_CONNECT_INFO that describes the connection to the non-Oracle system.

The default initialization parameter file already has an entry for this parameter. The syntax for HS_FDS_CONNECT_INFO for the gateways are as follows:

HS_FDS_CONNECT_INFO=IP_address:Port_number/Database_name,Type

Where IP_address is the hostname or IP address of the DB2 DRDA server

Port_number is the port number of the DB2 DRDA server.

Database_name is the database name of the DB2 server

Type (case insensitive) is one of the following:

• ZOS (DB2 UDB for z/OS),

• IOS (DB2 UDB for iSeries), or

• LUW (DB2 UDB for Linux, Unix, or Windows)

This release of gateway can support IPv6. If IPv6 address format is to be specified, you would need to wrap square brackets around the IPv6 specification to indicate the separation from the port number.

For example,

HS_FDS_CONNECT_INFO=[2001:0db8:20C:F1FF:FEC6:38AF]:1300/DB2M,ZOS

B.3.14 HS_FDS_RECOVERY_ACCOUNT

Specifies the name of the recovery account used for the commit-confirm transaction model. An account with user name and password must be set up at the non-Oracle system. For more information about the commit-confirm model, see the HS_TRANSACTION_MODEL parameter.

For DRDA, HS_FDS_RECOVERY_ACCOUNT specifies the user ID that is used by the gateway if a distributed transaction becomes in doubt. This user ID must have execute privileges on the package and must be defined to the IBM database.

If a distributed transaction becomes in doubt, then the Oracle database determines the status of the transaction by connecting to the IBM database, using the HS_FDS_RECOVERY_ACCOUNT. If this parameter is missing, then the gateway attempts to connect to a user ID of ORARECOV.

The name of the recovery account is case-sensitive.

B.3.15 HS_FDS_RECOVERY_PWD

Specifies the password of the recovery account used for the commit-confirm transaction model set up at the non-Oracle system. For more information about the commit-confirm model, see the HS_TRANSACTION_MODEL parameter.

HS_FDS_RECOVERY_PWD is used with the HS_FDS_RECOVERY_ACCOUNT. The recovery user connects to the IBM database if a distributed transaction is in doubt.

The name of the password of the recovery account is case-sensitive.

B.3.16 HS_FDS_DEFAULT_OWNER

The name of the table owner that is used for the non-Oracle database tables if an owner is not specified in the SQL statements.

B.3.17 HS_FDS_FETCH_ROWS

HS_FDS_FETCH_ROWS specifies the fetch array size. This is the number of rows to be fetched from the non-Oracle database and to return to Oracle database at one time. This parameter will be affected by the HS_RPC_FETCH_SIZE and HS_RPC_FETCH_REBLOCKING parameters.

B.3.18 HS_FDS_TRACE_LEVEL

Specifies whether error tracing is turned on or off for gateway connectivity.

The following values are valid:

• OFF disables the tracing of error messages.

• ON enables the tracing of error messages that occur when you encounter problems. The results are written by default to a gateway log file in LOG directory where the gateway is installed.

• DEBUG enables the tracing of detailed error messages that can be used for debugging.

B.3.19 HS_FDS_TRANSACTION_LOG

Specifies the name of the table created in the non-Oracle system for logging transactions. For more information about the transaction model, see the HS_TRANSACTION_MODEL parameter.

B.3.20 HS_IDLE_TIMEOUT

This feature is only available for Oracle Net TCP protocol.

When there is no activity for a connected gateway session for this specified time period, the gateway session would be terminated automatically with pending update (if any) rolled back.

B.3.21 HS_FDS_MBCS_TO_GRAPHIC

If set to TRUE, any single-byte character meant to insert to DB2 (var)graphic column would be converted to equivalent double-byte value before the insert operation.

B.3.22 HS_FDS_GRAPHIC_TO_MBCS

If set to TRUE, any double-byte characters in DB2 (var)graphic column that can have equivalent single-byte equivalent would be translated to equivalent single-byte before sending to the user.

B.3.23 HS_FDS_TIMESTAMP_MAPPING

If set to CHAR (default), DB2 timestamp would be mapped to CHAR(26). If set to TIMESTAMP, DB2 timestamp would be mapped to Oracle timestamp.

B.3.24 HS_FDS_QUOTE_IDENTIFIER

By default, the gateway will quote identifiers if the FDS supports it. However, we give the user the ability to overwrite the behavior.

B.3.25 HS_FDS_CAPABILITY

If the HS_FDS_CAPABILITY is set to ON then the specified function will be sent to DB2 for processing. In other words, post processing will be not needed for that function.

If the HS_FDS_CAPABILITY is set to OFF then the specified function will be not be sent to DB2 for processing. In other words, it will be post processed.

If the HS_FDS_CAPABILITY is set to SKIP then the specified function will be stripped from the SQL statement sent to DB2. In other words the function will be ignored.

B.3.26 HS_FDS_ISOLATION_LEVEL

HS_FDS_ISOLATION_LEVEL specifies the isolation level that is defined to the package when it is created. All SQL statements that are sent to the remote DRDA database are executed with this isolation level. Isolation level seriously affects performance of applications. Use caution when specifying an isolation level other than the default. For information on isolation levels, refer to your IBM database manuals.

The following table lists the isolation levels and their descriptions. The levels are specified in ascending order of control, with CHG having the least reliable cursor stability and RR having the most. Note that higher stability uses more resources on the server and can lock those resources for extended periods.

B.3.27 HS_FDS_PACKAGE_COLLID

HS_FDS_PACKAGE_COLLID specifies the package collection ID. Note that in DB2 UDB for iSeries, the collection ID is actually the name of an AS/400 library.

B.3.28 HS_NLS_LENGTH_SEMANTICS

This release of gateway has Character Semantics functionality equivalent to the Oracle Database Character Semantics, that is, NLS_LENGTH_SEMANTICS. When HS_NLS_LENGTH_SEMANTICS is set to CHAR, the (VAR)CHAR columns of UDB database are to be interpreted as having CHAR semantics. The only situation the gateway does not honor the HS_NLS_LENGTH_SEMANTICS=CHAR setting is when both Oracle database and the gateway are on the same multi-byte character set

B.3.29 HS_KEEP_REMOTE_COLUMN_SIZE

HS_KEEP_REMOTE_COLUMN_SIZE specifies whether to suppress ratio expansion when computing the length of (VAR)CHAR datatypes during data conversion from UDB database to the gateway, and then to the Oracle database. When it is set to REMOTE, the expansion is suppressed between the non-Oracle database to the gateway. When it is set to LOCAL, the expansion is suppressed between the gateway and Oracle database. When it is set to ALL, the expansion is suppressed from the non-Oracle database to the Oracle database.

When the parameter is set, the expansion is suppressed when reporting the remote column size, calculating the implicit resulting buffer size, and instantiating in the local Oracle database. This has effect only for remote column size from the non-Oracle database to Oracle database. If the gateway runs on Windows and HS_LANGUAGE=AL32UTF8, then you must not specify this parameter, as it would influence other ratio related parameter operation. It has no effect for calculating ratio for data moving from Oracle database to non-Oracle database through gateway during INSERT, UPDATE, or DELETE.

B.3.30 HS_FDS_RESULTSET_SUPPORT

Enables result sets to be returned from stored procedures. By default, all stored procedures do not return a result set to the user.

B.3.31 HS_FDS_REMOTE_DB_CHARSET

This parameter is valid only when HS_LANGUAGE is set to AL32UTF8 and the gateway runs on Windows. As more Oracle databases and non-Oracle databases use Unicode as database character sets, it is preferable to also run the gateway in Unicode character set. To do so, you must set HS_LANGUAGE=AL32UTF8. However, when the gateway runs on Windows, the Microsoft ODBC Driver Manager interface can exchange data only in the double-byte character set, UCS2. This results in extra ratio expansion of described buffer and column sizes. To compensate, the gateway can re-adjust the column size if HS_FDS_REMOTE_DB_CHARSET is set to the corresponding non-Oracle database character set. For example, HS_FDS_REMOTE_DB_CHARSET=KO16KSC5601.

B.3.32 HS_FDS_SUPPORT_STATISTICS

We gather statistics from the non-Oracle database by default. You can choose to disable the gathering of remote database statistics by setting the HS_FDS_SUPPORT_STATISTICS parameter to FALSE.

B.3.33 HS_FDS_RSET_RETURN_ROWCOUNT

When set to TRUE, the gateway returns the row counts of DML statements that are executed inside a stored procedure. The row count is returned as a single row, single column result set of type signed integer.

When set to FALSE, the gateway skips the row counts of DML statements that are executed inside a stored procedure. This is the default behavior, and it is the behavior of 11.1 and older gateways.

B.3.34 HS_FDS_AUTHENTICATE_USER

Specifies the way in which user ID and password are sent to the remote DB2 server and authenticated. Valid values are:

• CLEARTEXT : user ID and password are sent in clear text to server (default).

• ENCRYPT : password is sent encrypted to server.

• ENCRYPT_BOTH : user ID and password are sent encrypted to server.

• CLIENT : user ID is validated on the client side instead of by the server.

• KERBEROS : uses Kerberos to authenticate user ID.

B.3.35 HS_FDS_ENCRYPT_SESSION

Specifies the way the session to DB2 is encrypted. Valid values are:

• NONE : data session is not encrypted (default).

• SSL : Use SSL to encrypt data session (supported only by DB2 for iSeries).

• DB2 : Use DB2 encryption protocol for data session (supported only by DB2 for LUW and DB2 for z/OS, and can be used only when authentication is CLEARTEXT, ENCRYPT, or ENCRYPT_BOTH).

B.3.36 HS_FDS_TRUSTSTORE_FILE

Specifies the path that specifies the location of the truststore file. The truststore file contains a list of the valid Certificate Authorities (CAs) that are trusted by the client machine for SSL server authentication.

B.3.37 HS_FDS_TRUSTSTORE_PASSWORD

Specifies the password required to access the truststore.

B.3.38 HS_FDS_SQLLEN_INTERPRETATION

This parameter is only valid for 64 bit platforms. ODBC standard specifies SQLLEN (of internal ODBC construct) being 64 bit on 64 bit platforms, but some ODBC driver managers and drivers violate this convention, and implement it as 32 bit. In order for the gateway to compensate their behavior, you need to specify HS_FDS_SQLLEN_INTERPRETATION=32 if you use these types of driver managers and driver.