Oracle Transparent Gateway for Ingres II Administrator's Guide Release 8.1.6 Part Number A82871-01 |
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This chapter contains information specific to this release of the Oracle Transparent Gateway for Ingres II, and contains the following sections:
This table lists the versions of the components included on the distribution CD-ROM. All components are at production level.
This section describes the following:
The following table summarizes the hardware requirements for the Oracle Transparent Gateway for Ingres II.
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The system software configuration described in this section is supported by Oracle Corporation as long as the underlying system software products are supported by their respective vendors. Verify the latest support status with your system software vendors.
The following table summarizes the software requirements for the Oracle Transparent Gateway for Ingres II.
The following table provides the tested configurations at Oracle, at the time of this document release. Oracle continues to provide support for the most recent releases of Oracle and non-Oracle systems in a timely manner. For current supported configuration information, please contact Oracle Support Services or visit http://www.oracle.com/gateways
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Gateway Configurations for the Oracle database server release 8.1.6 | |
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Database | Gateway and Operating System |
Ingres II Version 2.0 |
tg4ingr release 8.1.6 running on Sun SPARC Solaris Versions 2.6 and 2.7 |
Ingres II and Oracle databases function differently in some areas, causing compatibility problems. The following compatibility issues are described in this section:
Naming rule issues include the following:
Oracle and Ingres II use different database object naming rules. For example, the maximum number of characters allowed for each object name can be different. Also, the use of quotation marks, case sensitivity, and the use of alphanumeric characters can all be different.
Names of Ingres II database objects are limited to a maximum of 32 characters. An object name can be composed of these characters:
Ingres II handles letter case differently from Oracle. Ingres II uses the following rules:
The Oracle database server defaults to uppercase unless you surround identifiers with double quote characters. For example, to refer to a Ingres II table called emp, enter the name with double quote characters as follows:
SQL> SELECT * FROM "emp"@INGR;
However, to refer to a Ingres II table called emp owned by Scott from an Oracle application, enter the following:
SQL> SELECT * FROM "Scott"."emp"@INGR;
If the Ingres II table called emp is owned by SCOTT, a table owner name in uppercase letters, you can enter the owner name without double quote characters as follows:
SQL> SELECT * FROM SCOTT."emp"@INGR;
or
SQL> SELECT * FROM scott."emp"@INGR;
Oracle Corporation recommends that you surround all Ingres II object names with double quote characters and use the exact letter case for the object names as they appear in the Ingres II data dictionary. This convention is not required when referring to the supported Oracle data dictionary tables or views listed in Appendix B, "Data Dictionary".
If existing applications cannot be changed according to these conventions, create views in Oracle to associate Ingres II names to the correct letter case. For example, to refer to the Ingres II table emp from an existing Oracle application by using only uppercase names, define the following view:
SQL> CREATE VIEW EMP (EMPNO, ENAME, SAL, HIREDATE)
AS SELECT "empno", "ename", "sal", "hiredate"
FROM "emp"@INGR;
With this view, the application can issue statements such as the following:
SQL> SELECT EMPNO, ENAME FROM EMP;
Using views is a workaround solution that duplicates data dictionary information originating in the Ingres II data dictionary. You must be prepared to update the Oracle view definitions whenever the data definitions for the corresponding tables are changed in the Ingres II database.
Data type issues include the following:
The Oracle database server supports dates through December 31, 4712. Ingres II supports dates in the range of January 1, 1582 through December 31, 2382. If a date beyond the range of Ingres II is passed to the Ingres II database, an error is returned.
When only a time value is given for a DATE datatype field, Ingres II adds the current date to the time value, while the Oracle database server adds the date of the first day.
Ingres II does not support implicit conversions between character data types and numeric data types. Such conversions must be explicit.
Query issues include the following:
The gateway passes the empty string to the Ingres II database without any conversion.
The gateway returns an empty string to the Oracle database server as a NULL value. This applies only to columns defined with a VARCHAR data type.
The gateway passes empty bind variables to the Ingres II database as a NULL value. This applies only to columns defined with a VARCHAR data type.
The locking model for a Ingres II database differs significantly from the Oracle model. The gateway depends on the underlying Ingres II behavior, so Oracle applications that access Ingres II through the gateway can be affected by the following possible scenarios:
This section describes the following known restrictions and includes suggestions for dealing with them when possible:
The following restriction also applies:
The gateway cannot guarantee transactional integrity in the following cases:
The gateway does not support savepoints. If a distributed update transaction is under way involving the gateway and a user attempts to create a savepoint, the following error occurs:
ORA-02070: database dblink does not support savepoint in this context
By default, the gateway is configured as COMMIT_CONFIRM and it is always the commit point site when the Ingres II database is updated by the transaction.
Any COMMIT or ROLLBACK issued in a PL/SQL cursor loop closes all open cursors, which can result in the following error:
ORA-1002: fetch out of sequence To prevent this error, move the COMMIT or ROLLBACK statement outside the cursor loop.
Oracle Corporation recommends that you place a DDL statement in its own transaction when executing such a statement with the pass-through feature. An explicit COMMIT must be issued after the DDL statement.
If the SQL statements being passed through the gateway result in an implicit commit at the Ingres II database, the Oracle transaction manager is unaware of the commit and an Oracle ROLLBACK command cannot be used to roll back the transaction.
The gateway supports only INSERT and UPDATE of LONG BYTE and LONG VARCHAR data up to 31,900 bytes and 61,900 bytes, respectively, when using bind variables.
An unsupported SQL function cannot be used in an SQL statement which accesses a column defined as Ingres II data type LONG BYTE or LONG VARCHAR. See Appendix A, "Supported SQL Syntax and Functions" for more information.
You cannot use SQL*Plus to select data from a column defined as Ingres II data type LONG BYTE or LONG VARCHAR when the data is greater than 80 characters in length. Oracle Corporation recommends using Pro*C or Oracle Call Interface to access such data in a Ingres II database.
The gateway does not support the PL/SQL function COLUMN_VALUE_LONG of the DBMS_SQL package.
This section lists restrictions on the following SQL syntax:
Appendix A, "Supported SQL Syntax and Functions" for more information about restrictions on SQL syntax.
See Also:
UPDATE and DELETE statements with the WHERE CURRENT OF clause are not supported by the gateway because they rely on the Oracle ROWID implementation. To update or delete a row through the gateway, a condition style WHERE clause must be used.
The CONNECT BY clause in a SELECT statement is not supported.
A SELECT statement of this syntax:
SQL> SELECT ... FROMtable_list
FOR UPDATE LISTcolumn_list
is supported only when column_list
refers to columns of the first table in table_list
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Subqueries in the SET clause of an UPDATE statement are not supported.
Whenever the use of a condition is allowed in an UPDATE statement, the gateway allows the condition to contain a subquery. Each subquery, however, must reference an Ingres II table. For example, using the table GTW_DEPT, the following statement results in a 10% salary increase for all employees working in the RESEARCH department:
SQL> UPDATE "gtw_emp"@INGR SET "sal"="sal" * 1.1
2 WHERE "deptno"=(SELECT "deptno" FROM "gtw_dept"@INGR
3 WHERE "dname"='RESEARCH');
If "gtw_dept"@INGR is replaced by "dept" in the subquery, where dept is the same table but located in the Oracle database, the following error results after the statement is issued:
ORA-02025: All tables in the SQL statement must be at the remote database.
The Oracle ROWID implementation is not supported.
In SQL*Plus, the gateway does not support using a SELECT statement to retrieve data from an Ingres II column defined as data type BYTE.
The gateway does not support the SQL*Plus COPY command for lowercase table names.
The gateway is not multithreaded and cannot support shared database links. Each gateway session spawns a separate gateway process and connections cannot be shared.
The gateway supports all single byte ASCII character sets and the following multibyte character sets:
The gateway does not support the procedure feature that allows the execution of stored procedures in a non-Oracle database.
This section describes known problems and includes suggestions for correcting them when possible. If you have any questions or concerns about the problems, contact Oracle Support Services. A current list of problems is available online. Contact your local Oracle Corporation office for information about accessing the list.
The following known problems are described in this section:
The Oracle database server supports an Oracle initialization parameter, DBLINK_ENCRYPT_LOGIN. When this parameter is set to TRUE, the password for the login user ID is not sent over the network.
If this parameter is set to TRUE in the initialization parameter file used by the Oracle database server, you must change the setting to FALSE to allow Oracle to communicate with the gateway.
The Oracle database server does not send the gateway a SELECT statement containing an aggregate function that is part of a CREATE TABLE or CREATE VIEW statement. For example, it does not send the following statement:
CREATE TABLE sum_calls_table AS
SELECT SUM(calls_abandoned), SUM(calls_completed),
SUM(calls_failed) FROM monthly_calls@INGR;
Instead, Oracle interprets what the SQL statement requests and sends the gateway a statement or statements to retrieve the data required for the request. After the data is retrieved, Oracle performs the aggregate function originally requested and passes the results to the application.
A solution to this problem is to use a different series of SQL statements. For example, instead of using the CREATE TABLE statement in the above example, use the following statements:
DROP TABLE sum_calls_table;
CREATE TABLE sum_calls_table (x1sum NUMBER, x2sum NUMBER,
x3sum NUMBER);
DECLARE
x1 NUMBER;
x2 NUMBER;
x3 NUMBER;
BEGIN
SELECT SUM(calls_abandoned), SUM(calls_completed),
SUM(calls_failed) INTO x1, x2, x3 FROM monthly_calls@INGR;
INSERT INTO sum_calls_table VALUES (x1, x2, x3);
END;
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The following SQL expressions do not function correctly with the gateway:
date + number
number + date
date - number
date1 - date2
Statements with the above expressions are sent to the Ingres II database without any translation. Since Ingres II does not support these date arithmetic functions, the statements return an error.
Incorrect negative values might be returned from a SELECT statement that retrieves data from columns defined as MONEY that contain negative values near the precision limit.
If you concatenate numeric literals using the "||" or CONCAT operator when using the gateway to query an Ingres II database, the result is an arithmetic addition. For example, the result of the following statement is 18:
SQL> SELECT 9 || 9 FROM "dual"@INGR;
The result is 99 when using Oracle to query an Oracle database.
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