A Heterogeneous Services Initialization Parameters

A.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;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.

A.2 HS_COMMIT_POINT_STRENGTH

Specifies a value that determines the commit point site in a heterogeneous distributed transaction. HS_COMMIT_POINT_STRENGTH is similar to COMMIT_POINT_STRENGTH, described in the Oracle Database Reference.

Set the HS_COMMIT_POINT_STRENGTH initialization parameter to a value relative to the importance of the site that is the commit point site in a distributed transaction. The Oracle database server or non-Oracle system with the highest commit point strength becomes the commit point site. To ensure that a non-Oracle system never becomes the commit point site, set the value of the HS_COMMIT_POINT_STRENGTH initialization parameter to zero.

The HS_COMMIT_POINT_STRENGTH initialization parameter is important only if the non-Oracle system can participate in the two-phase protocol as a regular two-phase commit partner and as the commit point site. This is only the case if the transaction model is two-phase commit confirm (2PCC).

A.3 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.

A.4 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.

A.5 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.

A.6 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.

A.7 HS_FDS_CONNECT_INFO

Specifies the information needed to bind to the data provider, that is, the non-Oracle system. For Generic Connectivity, you can bind to an ODBC-based data source or to an OLE DB-based data source. The information that you provide depends on the platform and whether the data source is ODBC, OLE DB-based, or a transparent gateway.

This parameter is required if you are using Generic Connectivity.

HS_FDS_CONNECT_INFO=FILEDSN=dsn

HS_FDS_CONNECT_INFO=dsn

HS_FDS_CONNECT_INFO="UDLFILE=data_link"

A.8 HS_FDS_DEFAULT_SCHEMA_NAME

Specifies a default value for the owner column that will be returned in the data dictionary translation, when the value of the owner is null. For example:

HS_FDS_DEFAULT_SCHEMA_NAME = PUBLIC

A.9 HS_FDS_SHAREABLE_NAME

Specifies the full path name to the ODBC library. This parameter is required when you are using Generic Connectivity to access data from an ODBC provider on a UNIX machine. The HS_FDS_SHAREABLE_NAME initialization parameter should point to the location of the ODBC driver manager and not to the ODBC driver.

A.10 HS_FDS_TRACE_LEVEL

Specifies whether error tracing is enabled or disabled for Generic Connectivity and transparent gateways. Enable the tracing to see which error messages occur when you encounter problems.

For Generic Connectivity, the results are written to a Generic Connectivity log file, in the /log directory under the $ORACLE_HOME/hs directory.

For transparent gateways, the location is the $ORACLE_HOME/<gateway>/log directory.

A.11 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]

A.12 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.

A.13 HS_NLS_DATE_FORMAT

Defines the date format for dates used by the target system. This initialization parameter has the same function as the NLS_DATE_FORMAT initialization parameter for an Oracle database server. The value can be any valid date mask listed in the Oracle Database SQL Reference, but must match the date format of the target system. For example, if the target system stores the date February 14, 2001 as 2001/02/14, set the parameter to yyyy/mm/dd. Note that characters must be lowercase.

A.14 HS_NLS_DATE_LANGUAGE

Specifies the language used in character date values coming from the non-Oracle system. Date formats can be language independent. For example, if the format is dd/mm/yyyy, all three components of the character date are numeric. In the format dd-mon-yyyy, however, the month component is the name abbreviated to three characters. The abbreviation is language dependent. For example, the abbreviation for the month April is "apr", which in French is "avr" (Avril).

Heterogeneous Services assumes that character date values fetched from the non-Oracle system are in this format. Also, Heterogeneous Services sends character date bind values in this format to the non-Oracle system.

A.15 HS_NLS_NCHAR

Informs Heterogeneous Services of the value of the national character set of the non-Oracle data source. This value is the non-Oracle equivalent to the NATIONAL CHARACTER SET parameter setting in the Oracle CREATE DATABASE statement. The HS_NLS_NCHAR value should be the character set ID of a character set supported by the Oracle NLSRTL library.

A.16 HS_NLS_NUMERIC_CHARACTER

Specifies the characters to use as the group separator and the decimal character. The group separator separates integer groups (such as thousands, millions, and billions). The decimal character separates the integer portion of a number from the decimal portion.

A.17 HS_NLS_TIMESTAMP_FORMAT

Defines the timestamp format for dates used by the target system. This initialization parameter has the same function as the NLS_TIMESTAMP_FORMAT initialization parameter for an Oracle database server. The value can be any valid timestamp mask listed in the Oracle Database SQL Reference, but it must match the date format of the target system. Note that characters must be lowercase. For example:

HS_NLS_TIMESTAMP_FORMAT = yyyy-mm-dd hh:mi:ss.ff

A.18 HS_NLS_TIMESTAMP_TZ_FORMAT

Defines the default timestamp with time zone format for the timestamp with time zone format used by the target system. This parameter has the same function as the NLS_TIMESTAMP_TZ_FORMAT parameter for an Oracle database server. The value of can be any valid timestamp with time zone mask listed in the Oracle Database SQL Reference, but must match the date format of the target system. Note that characters must be lowercase. For example:

HS_NLS_TIMESTAMP_TZ_FORMAT = yyyy-mm-dd hh:mi:ss.ff tzh:tzm

A.19 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 server. Therefore, setting the same value as the OPEN_CURSORS initialization parameter in the Oracle database server is recommended.

A.20 HS_ROWID_CACHE_SIZE

Specifies the size of the Heterogeneous Services cache containing the non-Oracle system equivalent of ROWID. The cache contains the non-Oracle system ROWID needed to support the WHERE CURRENT OF clause in a SQL statement or a SELECT FOR UPDATE statement.

When the cache is full, the first slot in the cache is reused, then the second, and so on. Only the last HS_ROWID_CACHE_SIZE non-Oracle system ROWID is cached.

A.21 HS_RPC_FETCH_REBLOCKING

Controls whether Heterogeneous Services attempts to optimize performance of data transfer between the Oracle database server 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 server 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.

A.22 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 response time or 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.

A.23 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

A.24 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.