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Oracle® Database Gateway for Informix User's Guide
11g Release 1 (11.1)

B31047-03
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D Initialization Parameters

The Oracle database initialization parameters in the init.ora file are distinct from gateway initialization parameters. Set the gateway parameters in the initialization parameter file using an agent-specific mechanism, or set them in the Oracle data dictionary using the DBMS_HS package. The gateway initialization parameter file must be available when the gateway is started.

This appendix contains a list of the gateway initialization parameters that can be set for each gateway and their description. It also describes the initialization parameter file syntax. It includes the following sections:

D.1 Initialization Parameter File Syntax

The syntax for the initialization parameter file is as follows:

  1. The file is a sequence of commands.

  2. Each command should start on a separate line.

  3. End of line is considered a command terminator (unless escaped with a backslash).

  4. If there is a syntax error in an initialization parameter file, none of the settings take effect.

  5. Set the parameter values as follows:

    [SET][PRIVATE] parameter=value
    

    Where:

    parameter is an initialization parameter name. It is a string of characters starting with a letter and consisting of letters, digits and underscores. Initialization parameter names are case sensitive.

    value is the initialization parameter value. It is case-sensitive. An initialization parameter value is either:

    1. A string of characters that does not contain any backslashes, white space or double quotation marks (")

    2. A quoted string beginning with a double quotation mark and ending with a double quotation mark. The following can be used inside a quoted string:

      • backslash (\) is the escape character

      • \n inserts a new line

      • \t inserts a tab

      • \" inserts a double quotation mark

      • \\ inserts a backslash

      A backslash at the end of the line continues the string on the next line. If a backslash precedes any other character then the backslash is ignored.

    For example, to enable tracing for an agent, set the HS_FDS_TRACE_LEVEL initialization parameter as follows:

    HS_FDS_TRACE_LEVEL=ON
    

    SET and PRIVATE are optional keywords. You cannot use either as an initialization parameter name. Most parameters are needed only as initialization parameters, so you usually do not need to use the SET or PRIVATE keywords. If you do not specify either SET or PRIVATE, the parameter is used only as an initialization parameter for the agent.

    SET specifies that, in addition to being used as an initialization parameter, the parameter value is set as an environment variable for the agent process. Use SET for parameter values that the drivers or non-Oracle system need as environment variables.

    PRIVATE specifies that the initialization parameter should be private to the agent and should not be uploaded to the Oracle database. Most initialization parameters should not be private. If, however, you are storing sensitive information like a password in the initialization parameter file, then you may not want it uploaded to the server because the initialization parameters and values are not encrypted when uploaded. Making the initialization parameters private prevents the upload from happening and they do not appear in dynamic performance views. Use PRIVATE for the initialization parameters only if the parameter value includes sensitive information such as a user name or password.

    SET PRIVATE specifies that the parameter value is set as an environment variable for the agent process and is also private (not transferred to the Oracle database, not appearing in dynamic performance views or graphical user interfaces).

D.2 Oracle Database Gateway for Informix Initialization Parameters

This section lists all the initialization file parameters that can be set for the Oracle Database Gateway for Informix. They are as follows:

D.3 Initialization Parameter Description

The following sections describe all the initialization file parameters that can be set for gateways.

D.3.1 HS_DB_DOMAIN

Property Description
Default value WORLD
Range of values 1 to 199 characters

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.

Note:

The HS_DB_NAME and HS_DB_DOMAIN initialization parameters must combine to form a unique address in a cooperative server environment.

D.3.2 HS_DB_INTERNAL_NAME

Property Description
Default value 01010101
Range of values 1 to 16 hexadecimal characters

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.

D.3.3 HS_DB_NAME

Property Description
Default value HO
Range of values 1 to 8 characters

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.

D.3.4 HS_DESCRIBE_CACHE_HWM

Property Description
Default value 100
Range of values 1 to 4000

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.

D.3.5 HS_LANGUAGE

Property Description
Default value System-specific
Range of values Any valid language name (up to 255 characters)

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]

Note:

The globalization support initialization parameters affect error messages, the data for the SQL Service, and parameters in distributed external procedures.

D.3.5.1 Character Sets

Ideally, the character sets of the Oracle database and the non-Oracle data source are the same. If they are not the same, Heterogeneous Services attempts to translate the character set of the non-Oracle data source to the Oracle database character set, and back again. The translation can degrade performance. In some cases, Heterogeneous Services cannot translate a character from one character set to another.

Note:

The specified character set must be a superset of the operating system character set on the platform where the agent is installed.

D.3.5.2 Language

The language component of the HS_LANGUAGE initialization parameter determines:

  • Day and month names of dates

  • AD, BC, PM, and AM symbols for date and time

  • Default sorting mechanism

Note that Oracle does not determine the language for error messages for the generic Heterogeneous Services messages (ORA-25000 through ORA-28000). These are controlled by the session settings in the Oracle database.

Note:

Use the HS_NLS_DATE_LANGUAGE initialization parameter to set the day and month names, and the AD, BC, PM, and AM symbols for dates and time independently from the language.

D.3.5.3 Territory

The territory clause specifies the conventions for day and week numbering, default date format, decimal character and group separator, and ISO and local currency symbols. Note that the level of globalization support between the Oracle database and the non-Oracle data source depends on how the gateway is implemented.

D.3.6 HS_LONG_PIECE_TRANSFER_SIZE

Property Description
Default value 64 KB
Range of values Any value up to 2 GB

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.

D.3.7 HS_OPEN_CURSORS

Property Description
Default value 50
Range of values 1 to the value of Oracle's OPEN_CURSORS initialization parameter

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.

D.3.8 HS_RPC_FETCH_REBLOCKING

Property Description
Default value ON
Range of values OFF or ON

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.

D.3.9 HS_RPC_FETCH_SIZE

Property Description
Default value 50000
Range of values 1 to 10000000

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.

D.3.10 HS_TIME_ZONE

Property Description
Default value for '[+|-]hh:mm' Derived from the NLS_TERRITORY initialization parameter
Range of values for '[+|-]hh:mm' Any valid datetime format mask

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

D.3.11 HS_TRANSACTION_MODEL

Property Description
Default Value COMMIT_CONFIRM
Range of Values COMMIT_CONFIRM, READ_ONLY, SINGLE_SITE

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.

D.3.12 IFILE

Property Description
Default value None
Range of values Valid parameter file names

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.

D.3.13 HS_FDS_CONNECT_INFO

Property Description
Default Value None
Range of Values Not applicable

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:

HS_FDS_CONNECT_INFO=host_name:port_number/server_name/database_name

where, host_name is the host name or IP address of the machine hosting the Informix database, port_number is the port number of the Informix database server, server_name is the name of the Informix database server, and database_name is the Informix database name.

D.3.14 HS_FDS_DEFAULT_OWNER

Property Description
Default Value None
Range of Values Not applicable

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.

Note:

If this parameter is not specified and the owner is not explicitly specified in the SQL statement, then the user name of the Oracle user or the user name specified when creating the database link is used.

D.3.15 HS_FDS_RECOVERY_ACCOUNT

Property Description
Default Value RECOVER
Range of values Any valid user ID

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.

D.3.16 HS_FDS_RECOVERY_PWD

Property Description
Default Value RECOVER
Range of values Any valid password

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.

D.3.17 HS_FDS_TRACE_LEVEL

Property Description
Default Value OFF
Range of values OFF, ON, DEBUG

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.

D.3.18 HS_FDS_TRANSACTION_LOG

Property Description
Default Value HS_TRANSACTION_LOG
Range of Values Any valid table name

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.

D.3.19 HS_FDS_FETCH_ROWS

Property Description
Default Value 100
Range of Values Any integer between 1 and 1000
Syntax HS_FDS_FETCH_ROWS=num

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.