D Initialization Parameters

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;owner3.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.

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.

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.

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.

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.

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]

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.

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.

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 to 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.

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.

HS_TIME_ZONE

Specifies the default local time zone displacement for the current SQL session. The format mask, [+|-]hh:mm, is specified to indicate the hours and minutes before or after UTC (Coordinated Universal Time—formerly Greenwich Mean Time). For example:

HS_TIME_ZONE = [+ | -] hh:mm

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.

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

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

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 does not apply.

HS_FDS_CONNECT_INFO

HS_FDS_CONNECT_INFO which 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 gateway is as follows:

For UNIX:

HS_FDS_CONNECT_INFO=host_name[[:port_number]|/[instance_name]][/database_name]

where, host_name is the host name or IP address of the machine hosting the SQL Server database, port_number is the port number of the SQL Server database server, instance_name is the instance of SQL Server running on the machine, and database_name is the SQL Server database name.

Either of the variables port_number or instance_name can be used, but not both together. Optionally, they both can be omitted. The variable database_name is always optional. The slash (/) is required when a particular value is omitted. For example, all of the following entries are valid:

HS_FDS_CONNECT_INFO=host_name/instance_name/database_name
HS_FDS_CONNECT_INFO=host_name//database_name
HS_FDS_CONNECT_INFO=host_name:port_name//database_name
HS_FDS_CONNECT_INFO=host_name/instance_name
HS_FDS_CONNECT_INFO=host_name 

For Windows:

HS_FDS_CONNECT_INFO= host_name/[instance_name][/database_name]

where, host_name is the host name or IP address of the machine hosting the SQL Server database, instance_name is the instance of SQL Server running on the machine, and database_name is the SQL Server database name.

Both instance_name and database_name are optional. If instance_name is omitted and database_name is provided, the slash (/) is required. This can be shown as follows:

HS_FDS_CONNECT_INFO= host_name//database_name

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.

HS_FDS_PROC_IS_FUNC

Enables return values from functions. By default, all stored procedures and functions do not return a return value to the user.

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.

The name of the recovery account is case sensitive.

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.

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

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.

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.

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.

HS_FDS_REPORT_REAL_AS_DOUBLE

Enables Oracle Database Gateway for SQL Server to treat SINGLE FLOAT PRECISION fields as DOUBLE FLOAT PPRECISION fields.

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.