Oracle 11g Release 1 SQL Server database gateway User's Guide
Below you will find brief information for database gateway 11g Release 1 SQL Server. The Oracle Database Gateway for SQL Server allows Oracle client applications to access SQL Server data using SQL language. This gateway, in combination with Oracle database, creates the impression that all data is stored on a local Oracle database, even though it might be distributed across various locations.
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Oracle® Database Gateway for SQL Server
User’s Guide,
11g Release 1 (11.1)
B31049-02
July 2007
Oracle Database Gateway for SQL Server User’s Guide, 11g Release 1 (11.1)
B31049-02
Copyright © 2002, 2007, Oracle. All rights reserved.
Primary Author: Maitreyee Chaliha
Contributor: Vira Goorah, Juan Pablo Ahues-Vasquez, Peter Castro, Charles Benet, Peter Wong, and
Govind Lakkoju
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Contents
................................................................................................................................................................ vii
Overview
.................................................................................................................................................... 1-1
Heterogeneous Services Technology
.................................................................................................... 1-2
Oracle Database Gateways
..................................................................................................................... 1-2
2 SQL Server Gateway Features and Restriction
Using the Pass-Through Feature
........................................................................................................... 2-1
Executing Stored Procedures and Functions
....................................................................................... 2-2
Remote User-defined Function Support
.............................................................................................. 2-2
Database Compatibility Issues for SQL Server
.................................................................................. 2-6
Known Restrictions
.............................................................................................................................. 2-10
COMMIT or ROLLBACK in PL/SQL Cursor Loops Closes Open Cursors .......................... 2-11
iii
Known Problems
................................................................................................................................... 2-14
Case Descriptions
..................................................................................................................................... 3-1
Installation Media Contents
................................................................................................................... 3-2
Demonstration Files
................................................................................................................................. 3-2
Demonstration Requirements
Creating Demonstration Tables
............................................................................................................. 3-3
Case 1: Simple Queries
............................................................................................................................ 3-5
Case 2: A More Complex Query
............................................................................................................ 3-5
Case 3: Joining SQL Server Tables
........................................................................................................ 3-5
Case 4: Write Capabilities
....................................................................................................................... 3-5
Case 5: Data Dictionary Query
.............................................................................................................. 3-6
Case 6: The Pass-Through Feature
........................................................................................................ 3-6
Case 7: Executing Stored Procedures
.................................................................................................... 3-6
Data Type Conversion
............................................................................................................................ A-1
B Supported SQL Syntax and Functions
Supported SQL Statements
................................................................................................................... B-1
Oracle Functions
...................................................................................................................................... B-2
iv
Data Dictionary Support
........................................................................................................................ C-1
Data Dictionary Mapping
...................................................................................................................... C-3
Gateway Data Dictionary Descriptions
.............................................................................................. C-4
Initialization Parameter File Syntax
.................................................................................................... D-1
Oracle Database Gateway for SQL Server Initialization Parameters
........................................... D-2
Initialization Parameter Description
................................................................................................... D-3
v
List of Tables
Restricted DDL Statements.................................................................................................... 2-12
Data Type Conversions............................................................................................................ A-1
Oracle Data Dictionary View Names and SQL Server Equivalents .................................. C-3
ALL_CATALOG ....................................................................................................................... C-4
ALL_COL_COMMENTS ......................................................................................................... C-5
ALL_CONS_COLUMNS ......................................................................................................... C-5
ALL_CONSTRAINTS............................................................................................................... C-5
ALL_IND_COLUMNS ............................................................................................................. C-6
ALL_INDEXES .......................................................................................................................... C-6
ALL_OBJECTS........................................................................................................................... C-7
ALL_TAB_COLUMNS............................................................................................................. C-8
ALL_TAB_COMMENTS.......................................................................................................... C-9
ALL_TABLES ............................................................................................................................ C-9
ALL_USERS ............................................................................................................................. C-10
ALL_VIEWS............................................................................................................................. C-10
DBA_CATALOG..................................................................................................................... C-11
DBA_COL_COMMENTS....................................................................................................... C-11
DBA_OBJECTS ........................................................................................................................ C-11
DBA_TAB_COLUMNS .......................................................................................................... C-12
DBA_TAB_COMMENTS ....................................................................................................... C-13
DBA_TABLES.......................................................................................................................... C-13
DICT_COLUMNS ................................................................................................................... C-14
DICTIONARY ......................................................................................................................... C-14
DUAL........................................................................................................................................ C-14
TABLE_PRIVILEGES ............................................................................................................. C-15
USER_CATALOG ................................................................................................................... C-15
USER_COL_COMMENTS..................................................................................................... C-15
USER_CONS_COLUMNS ..................................................................................................... C-15
USER_CONSTRAINTS .......................................................................................................... C-16
USER_IND_COLUMNS......................................................................................................... C-16
USER_INDEXES...................................................................................................................... C-16
USER_OBJECTS ...................................................................................................................... C-18
USER_TAB_COLUMNS ........................................................................................................ C-18
USER_TAB_COMMENTS ..................................................................................................... C-19
USER_TABLES ........................................................................................................................ C-19
USER_USERS........................................................................................................................... C-21
USER_VIEWS .......................................................................................................................... C-21 vi
Preface
This manual describes the Oracle Database Gateway for SQL Server, which enables
Oracle client applications to access SQL Server data through Structured Query
Language (SQL). The gateway, with the Oracle database, creates the appearance that all data resides on a local Oracle database, even though the data can be widely distributed.
This preface covers the following topics:
■
■
■
■
Audience
This manual is intended for Oracle database administrators who perform the following tasks:
■
■
■
Installing and configuring the Oracle Database Gateway for SQL Server
Diagnosing gateway errors
Using the gateway to access SQL Server data
Note:
You should understand the fundamentals of Oracle
Database Gateways and the Microsoft Windows operating system before using this guide to install or administer the gateway.
Documentation Accessibility
Our goal is to make Oracle products, services, and supporting documentation accessible, with good usability, to the disabled community. To that end, our documentation includes features that make information available to users of assistive technology. This documentation is available in HTML format, and contains markup to facilitate access by the disabled community. Accessibility standards will continue to evolve over time, and Oracle is actively engaged with other market-leading technology vendors to address technical obstacles so that our documentation can be accessible to all of our customers. For more information, visit the Oracle Accessibility
Program Web site at http://www.oracle.com/accessibility/
Accessibility of Code Examples in Documentation
Screen readers may not always correctly read the code examples in this document. The conventions for writing code require that closing braces should appear on an otherwise empty line; however, some screen readers may not always read a line of text that consists solely of a bracket or brace.
vii
Accessibility of Links to External Web Sites in Documentation
This documentation may contain links to Web sites of other companies or organizations that Oracle does not own or control. Oracle neither evaluates nor makes any representations regarding the accessibility of these Web sites.
TTY Access to Oracle Support Services
Oracle provides dedicated Text Telephone (TTY) access to Oracle Support Services within the United States of America 24 hours a day, seven days a week. For TTY support, call 800.446.2398.
Related Documentation
For more information, see the following documents:
■
■
■
■
■
■
■
■
Oracle Database New Features Guide
Oracle Call Interface Programmer's Guide
Oracle Database Administrator's Guide
Oracle Database Advanced Application Developer's Guide
Oracle Database Concepts
Oracle Database Performance Tuning Guide
Oracle Database Error Messages
Oracle Database Globalization Support Guide
■
■
■
■
Oracle Database Reference
Oracle Database SQL Language Reference
Oracle Database Net Services Administrator's Guide
SQL*Plus User's Guide and Reference
■
■
Oracle Database Heterogeneous Connectivity Administrator's Guide
Oracle Database 2 Day DBA
■
Oracle Database Security Guide
Many of the examples in this book use the sample schemas of the seed database, which is installed by default when you install Oracle. Refer to Oracle Database Sample Schemas for information on how these schemas were created and how you can use them yourself.
Printed documentation is available for sale in the Oracle Store at http://oraclestore.oracle.com/
To download free release notes, installation documentation, white papers, or other collateral, please visit the Oracle Technology Network (OTN). You must register online before using OTN; registration is free and can be done at http://otn.oracle.com/technology/membership
If you already have a user name and password for OTN, then you can go directly to the documentation section of the OTN Web site at http://otn.oracle.com/technology/documentation/ viii
Conventions
The following text conventions are used in this document:
Convention boldface
italic
monospace
Meaning
Boldface type indicates graphical user interface elements associated with an action, or terms defined in text or the glossary.
Italic type indicates book titles, emphasis, or placeholder variables for which you supply particular values.
Monospace type indicates commands within a paragraph, URLs, code in examples, text that appears on the screen, or text that you enter.
ix
x
1
Introduction
This chapter introduces the challenge faced by organizations when running several different database systems. It briefly covers Heterogeneous Services, the technology that the Oracle Database Gateway for SQL Server is based on.
To get a good understanding of generic gateway technology, Heterogeneous Services,
Generic Connectivity, and how Oracle Database Gateways fit in the picture, reading
Oracle Database Heterogeneous Connectivity Administrator's Guide first is highly recommended.
This chapter contains the following sections:
■
■
■
Heterogeneous Services Technology
Overview
Heterogeneous data access is a problem that affects a lot of companies. A lot of companies run several different database systems. Each of these systems stores data and has a set of applications that run against it. Consolidation of this data in one database system is often hard-in large part because many of the applications that run against one database may not have an equivalent that runs against another. Until such time as migration to one consolidated database system is made feasible, it is necessary for the various heterogeneous database systems to interoperate.
Oracle Database Gateways provide the ability to transparently access data residing in a non-Oracle system from an Oracle environment. This transparency eliminates the need for application developers to customize their applications to access data from different non-Oracle systems, thus decreasing development efforts and increasing the mobility of the application. Applications can be developed using a consistent Oracle interface for both Oracle and SQL Server.
Gateway technology is composed of two parts: a component that has the generic technology to connect to a non-Oracle system, which is common to all the non-Oracle systems, called Heterogeneous Services, and a component that is specific to the non-Oracle system that the gateway connects to. Heterogeneous Services, in conjunction with the Oracle Database Gateway agent, enables transparent access to non-Oracle systems from an Oracle environment.
Introduction 1-1
Heterogeneous Services Technology
Heterogeneous Services Technology
Heterogeneous Services provides the generic technology for connecting to non-Oracle systems. As an integrated component of the database, Heterogeneous Services can exploit features of the database, such as the powerful SQL parsing and distributed optimization capabilities.
Heterogeneous Services extend the Oracle SQL engine to recognize the SQL and procedural capabilities of the remote non-Oracle system and the mappings required to obtain necessary data dictionary information. Heterogeneous Services provides two types of translations: the ability to translate Oracle SQL into the proper dialect of the non-Oracle system as well as data dictionary translations which displays the metadata of the non-Oracle system in the local format. For situations where no translations are available, native SQL can be issued to the non-Oracle system using the pass-through feature of Heterogeneous Services.
Heterogeneous Services also maintains the transaction coordination between Oracle and the remote non-Oracle system, such as providing the two-phase commit protocol to ensure distributed transaction integrity, even for non-Oracle systems that do not natively support two-phase commit.
See Also:
Oracle Database Heterogeneous Connectivity
Administrator's Guide for more information about Heterogeneous
Services.
Oracle Database Gateways
The capabilities, SQL mappings, data type conversions, and interface to the remote non-Oracle system are contained in the gateway. The gateway interacts with
Heterogeneous Services to provide the transparent connectivity between Oracle and non-Oracle systems.
The gateway can be installed on any machine independent of the Oracle or non-Oracle database. It can be the same machine as the Oracle database or on the same machine as the SQL Server database or on a third machine as a standalone.
1-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
2
SQL Server Gateway Features and
Restriction
After the gateway is installed and configured, you can use the gateway to access SQL
Server data, pass SQL Server commands from applications to the SQL Server database, perform distributed queries, and copy data.
This chapter contains the following sections:
■
Using the Pass-Through Feature
■
■
■
■
Executing Stored Procedures and Functions
Database Compatibility Issues for SQL Server
Using the Pass-Through Feature
The gateway can pass SQL Server commands or statements from the application to the
SQL Server database using the DBMS_HS_PASSTHROUGH package.
Use the DBMS_HS_PASSTHROUGH package in a PL/SQL block to specify the statement to be passed to the SQL Server database, as follows:
DECLARE
num_rows INTEGER;
BEGIN
num_rows := DBMS_HS_PASSTHROUGH.EXECUTE_IMMEDIATE@MSQL('command');
END;
/
Where command cannot be one of the following:
■
BEGIN
TRANSACTION
■
COMMIT
■
■
ROLLBACK
SAVE
■
■
■
■
SHUTDOWN
RELEASE
SAVEPOINT
CONNECT
SQL Server Gateway Features and Restriction 2-1
Executing Stored Procedures and Functions
■
SQL Server tool commands
The DBMS_HS_PASSTHROUGH package supports passing bind values and executing
SELECT statements.
Note:
TRUNCATE cannot be used in a pass-through statement.
See Also:
Oracle Database PL/SQL Packages and Types Reference and
Chapter 3, Features of Oracle Database Gateways and Generic
Connectivity, of Oracle Database Heterogeneous Connectivity
Administrator's Guide for more information about the DBMS_HS_
PASSTHROUGH
package.
Executing Stored Procedures and Functions
Using the procedural feature, the gateway can execute stored procedures that are defined in the SQL Server database. It is not necessary to relink the gateway or define the procedure to the gateway, but the procedure's access privileges must permit access by the user that the gateway is logging in as.
See Also:
Oracle Database Heterogeneous Connectivity
Administrator's Guide for more information about executing stored procedures.
Standard PL/SQL statements are used to execute a stored procedure.
The gateway supports stored procedures in three mutually exclusive modes:
■
■
■
Normal mode: Have access to IN/OUT arguments only
Return value mode: Have a return value for all stored procedures
Resultset mode: Out values are available as last result set
Remote User-defined Function Support
User-defined functions in a remote non-Oracle database can be used in SQL statements.
See Also:
Oracle Database Heterogeneous Connectivity
Administrator's Guide for more information about executing user-defined functions on a non-Oracle database.
Return Values and Stored Procedures
By default, all stored procedures and functions do not return a return value to the user. To enable return values, set the HS_FDS_PROC_IS_FUNC parameter in the initialization parameter file.
See Also:
Appendix D, "Initialization Parameters" for
information about both editing the initialization parameter file and the HS_FDS_PROC_IS_FUNC parameter.
2-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Remote User-defined Function Support
Note:
If you set the HS_FDS_PROC_IS_FUNC gateway initialization parameter, you must change the syntax of the procedure execute statement for all existing stored procedures.
In the following example, the employee name JOHN SMYTHE is passed to the SQL
Server stored procedure REVISE_SALARY. The stored procedure retrieves the salary value from the SQL Server database to calculate a new yearly salary for JOHN
SMYTHE
. The revised salary returned in RESULT is used to update EMP in a table of an
Oracle database:
DECLARE
INPUT VARCHAR2(15);
RESULT NUMBER(8,2);
BEGIN
INPUT := 'JOHN SMYTHE';
RESULT := REVISE_SALARY@
MSQL
(INPUT);
UPDATE EMP SET SAL = RESULT WHERE ENAME =: INPUT;
END;
/
The procedural feature automatically converts non-Oracle data types to and from
PL/SQL data types.
Result Sets and Stored Procedures
The Oracle Database Gateway for SQL Server provides support for stored procedures which return result sets.
By default, all stored procedures and functions do not return a result set to the user.
To enable result sets, set the HS_FDS_RESULTSET_SUPPORT parameter in the initialization parameter file.
See Also:
Appendix D, "Initialization Parameters"
for information about both editing the initialization parameter file and the HS_
FDS_RESULTSET_SUPPORT
parameter. For further information about Oracle support for result sets in non-Oracle databases see
Oracle Database Heterogeneous Connectivity Administrator's Guide.
Note:
If you set the HS_FDS_RESULTSET_SUPPORT gateway initialization parameter, you must change the syntax of the procedure execute statement for all existing stored procedures or errors will occur.
When accessing stored procedures with result sets through the Oracle Database
Gateway for SQL Server, you will be in the sequential mode of Heterogeneous
Services.
The Oracle Database Gateway for SQL Server returns the following information to
Heterogeneous Services during procedure description:
■
All the input arguments of the remote stored procedure
SQL Server Gateway Features and Restriction 2-3
Remote User-defined Function Support
■
■
None of the output arguments
One out argument of type ref cursor (corresponding to the first result set returned by the stored procedure)
Client programs have to use the virtual package function dbms_hs_result_ set.get_next_result_set
to get the ref cursor for subsequent result sets. The last result set returned is the out argument from the procedure.
The limitations of accessing result sets are the following:
■
Result sets returned by a remote stored procedure have to be retrieved in the order in which they were placed on the wire
■
On execution of a stored procedure, all result sets returned by a previously executed stored procedure will be closed (regardless of whether the data has been completely retrieved or not)
In the following example, the SQL Server stored procedure is executed to fetch the contents of the emp and dept tables from SQL Server: create procedure REFCURPROC (@arg1 varchar(255), @arg2 varchar(255) output) as select @arg2 = @arg1 select * from EMP select * from DEPT go
This stored procedure assigns the input parameter arg1 to the output parameter arg2, opens the query SELECT * FROM EMP in ref cursor rc1, and opens the query SELECT
* FROM DEPT
in ref cursor rc2.
OCI Program Fetching from Result Sets in Sequential Mode
The following example shows OCI program fetching from result sets in sequential mode:
OCIEnv *ENVH;
OCISvcCtx *SVCH;
OCIStmt *STMH;
OCIError *ERRH;
OCIBind *BNDH[3];
OraText arg1[20];
OraText arg2[255];
OCIResult *rset;
OCIStmt *rstmt; ub2 rcode[3]; ub2 rlens[3]; sb2 inds[3];
OraText *stmt = (OraText *) "begin refcurproc@MSQL(:1,:2,:3); end;";
OraText *n_rs_stm = (OraText *)
"begin :ret := DBMS_HS_RESULT_SET.GET_NEXT_RESULT_SET@MSQL; end;";
/* Prepare procedure call statement */
/* Handle Initialization code skipped */
OCIStmtPrepare(STMH, ERRH, stmt, strlen(stmt), OCI_NTV_SYNTAX, OCI_DEFAULT);
/* Bind procedure arguments */ inds[0] = 0; strcpy((char *) arg1, "Hello World"); rlens[0] = strlen(arg1);
2-4 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Remote User-defined Function Support
OCIBindByPos(STMH, &BNDH[0], ERRH, 1, (dvoid *) arg1, 20, SQLT_CHR,
(dvoid *) &(inds[0]), &(rlens[0]), &(rcode[0]), 0, (ub4 *) 0,
OCI_DEFAULT); inds[1] = -1;
OCIBindByPos(STMH, &BNDH[1], ERRH, 1, (dvoid *) arg2, 20, SQLT_CHR,
(dvoid *) &(inds[1]), &(rlens[1]), &(rcode[1]), 0, (ub4 *) 0,
OCI_DEFAULT); inds[2] = 0; rlens[2] = 0;
OCIDescriptorAlloc(ENVH, (dvoid **) &rset, OCI_DTYPE_RSET, 0, (dvoid **) 0);
OCIBindByPos(STMH, &BNDH[2], ERRH, 2, (dvoid *) rset, 0, SQLT_RSET,
(dvoid *) &(inds[2]), &(rlens[2]), &(rcode[2]),
0, (ub4 *) 0, OCI_DEFAULT);
/* Execute procedure */
OCIStmtExecute(SVCH, STMH, ERRH, 1, 0, (CONST OCISnapshot *) 0,
(OCISnapshot *) 0, OCI_DEFAULT);
/* Convert result set to statement handle */
OCIResultSetToStmt(rset, ERRH); rstmt = (OCIStmt *) rset;
/* After this the user can fetch from rstmt */
/* Issue get_next_result_set call to get handle to next_result set */
/* Prepare Get next result set procedure call */
OCIStmtPrepare(STMH, ERRH, n_rs_stm, strlen(n_rs_stm), OCI_NTV_SYNTAX,
OCI_DEFAULT);
/* Bind return value */
OCIBindByPos(STMH, &BNDH[1], ERRH, 1, (dvoid *) rset, 0, SQLT_RSET,
(dvoid *) &(inds[1]), &(rlens[1]), &(rcode[1]),
0, (ub4 *) 0, OCI_DEFAULT);
/* Execute statement to get next result set*/
OCIStmtExecute(SVCH, STMH, ERRH, 1, 0, (CONST OCISnapshot *) 0,
(OCISnapshot *) 0, OCI_DEFAULT);
/* Convert next result set to statement handle */
OCIResultSetToStmt(rset, ERRH); rstmt = (OCIStmt *) rset;
/* Now rstmt will point to the second result set returned by the remote stored procedure */
/* Repeat execution of get_next_result_set to get the output arguments */
PL/SQL Program Fetching from Result Sets in Sequential Mode
Assume that the table loc_emp is a local table exactly like the SQL Server emp table.
The same assumption applies for loc_dept. outargs is a table with columns corresponding to the out arguments of the SQL Server stored procedure.
create or replace package rcpackage is
type RCTYPE is ref cursor; end rcpackage;
/ declare
rc1 rcpackage.rctype;
SQL Server Gateway Features and Restriction 2-5
Database Compatibility Issues for SQL Server
rec1 loc_emp%rowtype;
rc2 rcpackage.rctype;
rec2 loc_dept%rowtype;
rc3 rcpackage.rctype;
rec3 outargs%rowtype;
out_arg varchar2(255); begin
-- Execute procedure
out_arg := null;
refcurproc@MSQL('Hello World', out_arg, rc1);
-- Fetch 20 rows from the remote emp table and insert them into loc_emp
for i in 1 .. 20 loop
fetch rc1 into rec1;
insert into loc_emp (rec1.empno, rec1.ename, rec1.job,
rec1.mgr, rec1.hiredate, rec1.sal, rec1.comm, rec1.deptno);
end loop;
-- Close ref cursor
close rc1;
-- Get the next result set returned by the stored procedure
rc2 := dbms_hs_result_set.get_next_result_set@MSQL;
-- Fetch 5 rows from the remote dept table and insert them into loc_dept
for i in 1 .. 5 loop
fetch rc2 into rec2;
insert into loc_dept values (rec2.deptno, rec2.dname, rec2.loc);
end loop;
--Close ref cursor
close rc2;
-- Get the output arguments from the remote stored procedure
-- Since we are in sequential mode, they will be returned in the
-- form of a result set
rc3 := dbms_hs_result_set.get_next_result_set@MSQL;
-- Fetch them and insert them into the outarguments table
fetch rc3 into rec3;
insert into outargs (rec3.outarg, rec3.retval);
-- Close ref cursor
close rc3; end;
/
Database Compatibility Issues for SQL Server
SQL Server and Oracle databases function differently in some areas, causing compatibility problems. The following compatibility issues are described in this section:
■
■
Implicit Transactions (Chained Mode)
2-6 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Database Compatibility Issues for SQL Server
■
■
■
■
Implicit Transactions (Chained Mode)
The gateway supports the ANSI-standard implicit transactions. SQL Server stored procedures must be written for this mode. Running implicit transactions allows the gateway to extend the Oracle two-phase commit protection to transactions updating
Oracle and SQL Server databases.
Column Definitions
By default, a SQL Server table column cannot contain null values unless NULL is specified in the column definition. SQL Server assumes all columns cannot contain null values unless you set a SQL Server option to override this default.
For an Oracle table, null values are allowed in a column unless NOT NULL is specified in the column definition.
Naming Rules
Naming rule issues include the following:
■
■
Rules for Naming Objects
Oracle and SQL Server 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 single and double quotation marks, case sensitivity, and the use of alphanumeric characters can all be different.
See Also:
Oracle Database Reference and SQL Server documentation.
Case Sensitivity
The Oracle database defaults to uppercase unless you surround identifiers with double quote characters. For example, to refer to the SQL Server table called emp, enter the name with double quote characters, as follows:
SQL> SELECT * FROM "emp"@MSQL;
However, to refer to the SQL Server table called emp owned by Scott from an Oracle application, enter the following:
SQL> SELECT * FROM "Scott"."emp"@MSQL;
If the SQL Server 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"@MSQL;
SQL Server Gateway Features and Restriction 2-7
Database Compatibility Issues for SQL Server
Or
SQL> SELECT * FROM scott."emp"@MSQL;
Oracle recommends that you surround all SQL Server object names with double quote characters and use the exact letter case for the object names as they appear in the SQL
Server data dictionary. This convention is not required when referring to the supported Oracle data dictionary tables or views listed in
.
If existing applications cannot be changed according to these conventions, create views in Oracle to associate SQL Server names to the correct letter case. For example, to refer to the SQL Server 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"@MSQL;
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 SQL Server data dictionary. You must be prepared to update the
Oracle view definitions whenever the data definitions for the corresponding tables are changed in the SQL Server database.
Data Types
Data type issues include the following:
■
■
■
Bind Variables With LONG Columns
Binary Literal Notation
Oracle SQL uses hexadecimal digits surrounded by single quotes to express literal values being compared or inserted into columns defined as data type RAW.
This notation is not converted to syntax compatible with the SQL Server VARBINARY and BINARY data types (a 0x followed by hexadecimal digits, surrounded by single quotes).
For example, the following statement is not supported:
SQL> INSERT INTO BINARY_TAB@MSQL VALUES ('0xff')
Where BINARY_TAB contains a column of data type VARBINARY or BINARY. Use bind variables when inserting into or updating VARBINARY and BINARY data types.
Bind Variables With LONG Columns
The gateway does not support using bind variables to update columns of data type
LONG
.
2-8 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Queries
Database Compatibility Issues for SQL Server
Data Type Conversion
SQL Server does not support implicit date conversions. Such conversions must be explicit.
For example, the gateway issues an error for the following SELECT statement:
SELECT DATE_COL FROM TEST@
MSQL
WHERE DATE_COL = "1-JAN-2004";
To avoid problems with implicit conversions, add explicit conversions, as in the following:
SELECT DATE_COL FROM TEST@
MSQL
WHERE DATE_COL = TO_DATE("1-JAN-2004")
See Also:
Appendix A, "Data Type Conversion"
for more information about restrictions on data types.
Query issues include the following:
■
■
■
Row Selection
SQL Server evaluates a query condition for all selected rows before returning any of the rows. If there is an error in the evaluation process for one or more rows, no rows are returned even though the remaining rows satisfy the condition.
Oracle evaluates the query condition row-by-row and returns a row when the evaluation is successful. Rows are returned until a row fails the evaluation.
Empty Strings
Oracle processes an empty string in a SQL statement as a null value. SQL Server processes an empty string as an empty string.
When comparing an empty string the gateway passes literal empty strings to the SQL
Server database without any conversion. If you intended an empty string to represent a null value, SQL Server does not process the statement that way; it uses the empty string.
You can avoid this problem by using NULL or IS NULL in the SQL statement instead of the empty string syntax, as in the following example:
SELECT * from "emp"@MSQL where "ename" IS NULL;
Selecting an empty string
For VARCHAR columns, the gateway returns an empty string to the Oracle database as
NULL
value.
For CHAR columns, the gateway returns the full size of the column with each character as empty space (’ ’).
SQL Server Gateway Features and Restriction 2-9
Known Restrictions
Empty Bind Variables
For VARCHAR bind variables, the gateway passes empty bind variables to the SQL
Server database as a NULL value.
Locking
The locking model for an SQL Server database differs significantly from the Oracle model. The gateway depends on the underlying SQL Server behavior, so Oracle applications that access SQL Server through the gateway can be affected by the following possible scenarios:
■
■
■
Read access might block write access
Write access might block read access
Statement-level read consistency is not guaranteed
See Also:
SQL Server documentation for information about the
SQL Server locking model.
Known Restrictions
If you encounter incompatibility problems not listed in this section or in
Problems" on page 2-14, contact Oracle Support Services. The following section
describes the known restrictions and includes suggestions for dealing with them when possible:
■
■
■
■
■
■
■
■
■
■
■
COMMIT or ROLLBACK in PL/SQL Cursor Loops Closes Open Cursors
SQL*Plus COPY Command with Lowercase Table Names
Note:
If you have any questions or concerns about the restrictions, contact Oracle Support Services.
Multiple Open Statements
Accessing SQL Server has the limitation that one open statement or cursor is allowed for each connection. If a second statement or cursor needs to open in the same transaction to access SQL Server, it requires a new connection.
Because of this limitation multiple open statements or cursors within the same transaction can lock each other because they use different connections to SQL Server.
To avoid this restriction, issue a commit, or modify the logic, or both.
2-10 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Known Restrictions
Transactional Integrity
The gateway cannot guarantee transactional integrity in the following cases:
■
■
When a statement that is processed by the gateway causes an implicit commit in the target database
When the target database is configured to work in autocommit mode
Note:
Oracle strongly recommends the following:
■
If you know that executing a particular statement causes an implicit commit in the target database, then ensure that this statement is executed in its own transaction.
The gateway sets Autocommit Mode to Off when a connection is established to the
SQL Server database.
Transaction Capability
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.
COMMIT or ROLLBACK in PL/SQL Cursor Loops Closes Open Cursors
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.
Stored Procedures
Changes issued through stored procedures that embed commits or rollbacks cannot be controlled by the Oracle transaction manager or Oracle COMMIT or ROLLBACK commands.
When accessing stored procedures with result sets through the Oracle Database
Gateway for SQL Server, you must work in the sequential mode of Heterogeneous
Services.
When accessing stored procedures with multiple result sets through the Oracle
Database Gateway for SQL Server, you must read all the result sets before continuing.
Output parameters of stored procedures must be initialized to an empty string.
Pass-Through Feature
If the SQL statements being passed through the gateway result in an implicit commit at the SQL Server database, the Oracle transaction manager is unaware of the commit and an Oracle ROLLBACK command cannot be used to roll back the transaction.
SQL Server Gateway Features and Restriction 2-11
Known Restrictions
DDL Statements
SQL Server requires some DDL statements to be executed in their own transaction, and only one DDL statement can be executed in a given transaction.
If you use these DDL statements in a SQL Server stored procedure and you execute the stored procedure through the gateway using the procedural feature, or, if you execute the DDL statements through the gateway using the pass-through feature, an error condition might result. This is because the procedural feature and the pass-through feature of the gateway cannot guarantee that the DDL statements are executed in their own separate transaction.
The following SQL Server DDL statements can cause an error condition if you attempt to pass them with the gateway pass-through feature, or if you execute a SQL Server stored procedure that contains them:
Table 2–1 Restricted DDL Statements
Statement Name
ALTER DATABASE
CREATE DATABASE
CREATE INDEX
CREATE PROCEDURE
CREATE TABLE
CREATE VIEW
DISK INIT
DROP <object>
DUMP TRANSACTION
GRANT
LOAD DATABASE
LOAD TRANSACTION
RECONFIGURE
REVOKE
SELECT INTO
TRUNCATE TABLE
UPDATE STATISTICS
See Also:
SQL Server documentation for more information about
DDL statements.
SQL Syntax
This section lists restrictions on the following SQL syntax:
■
■
■
2-12 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Known Restrictions
■
■
■
■
■
■
Data Dictionary Table and Views in UPDATE Statement
See Also:
Appendix B, "Supported SQL Syntax and Functions"
for more information about restrictions on SQL syntax.
WHERE CURRENT OF Clause
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 specific row through the gateway, a condition style WHERE clause must be used.
CONNECT BY Clause
The gateway does not support the CONNECT BY clause in a SELECT statement.
Functions in Subqueries
Bind variables and expressions are not supported as operands in string functions or mathematical functions, when part of subquery in an INSERT, UPDATE, or DELETE
SQL statement.
Parameters in Subqueries
Due to a limitation in SQL Server, you cannot use parameters in subqueries.
Data Dictionary Table and Views in UPDATE Statement
Data dictionary tables and views in the SET clause of an UPDATE statement are not supported.
ROWID
The Oracle ROWID implementation is not supported.
TO_DATE
TO_DATE
is a reserved word and cannot be used as a database identifier name.
EXPLAIN PLAN Statement
The EXPLAIN PLAN statement is not supported.
Callback Support
SQL statements that require the gateway to callback to Oracle database would not be supported.
The following categories of SQL statements will result in a callback:
■
Any DML with a sub-select, which refers to a table in Oracle database. For example:
INSERT INTO emp@non_oracle SELECT * FROM oracle_emp;
SQL Server Gateway Features and Restriction 2-13
Known Problems
■
Any DELETE, INSERT, UPDATE or "SELECT... FOR UPDATE..." SQL statement containing SQL functions or statements that need to be executed at the originating Oracle database.
These SQL functions include USER, USERENV, and SYSDATE, and the SQL statements are in selects of data from the originating Oracle database. For example:
DELETE FROM emp@non_oracle WHERE hiredate > SYSDATE;
■
SELECT ename FROM tkhoemp@non_oracle
WHERE hiredate IN (SELECT hiredate FROM tkhoemp)
FOR UPDATE OF empno;
Any SQL statement that involves a table in Oracle database, and a LONG or LOB column in a remote table. For example:
SELECT a.long1, b.empno FROM scott.table@non_oracle a, emp b
WHERE a.id=b.empno;
SELECT a.long1, b.dummy FROM table_non@non_oracle a, dual b; where a.long1 is a LONG column.
Functions
The following restrictions apply to using functions:
■
Unsupported functions cannot be used in statements that refer to LONG columns.
■
When negative numbers are used as the second parameter in a SUBSTR function, incorrect results are returned. This is due to incompatibility between the Oracle
SUBSTR
function and the equivalent in SQL Server.
SQL*Plus COPY Command with Lowercase Table Names
You need to use double quotes to wrap around lowercase table names.
For example: copy from tkhouser/tkhouser@inst1 insert loc_tkhodept using select * from
"tkhodept"@holink2;
Database Links
The gateway is not multithreaded and cannot support shared database links. Each gateway session spawns a separate gateway process and connections cannot be shared.
Known Problems
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 office for information about accessing the list.
The following known problems are described in this section:
■
2-14 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Known Problems
■
■
■
■
■
■
SQL Server IMAGE, TEXT and NTEXT Data Types
Data Dictionary Views and PL/SQL
Encrypted Format Login
The Oracle9i database (Release 9.2 and earlier) supported 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 Oracle9i database, you must change the setting to FALSE, the default setting, to allow Oracle9i to communicate with the gateway.
In the current release, Oracle Database 11g, Release 11.1, the DBLINK_ENCRYPT_
LOGIN
initialization parameter is obsolete, so you need not check it.
Date Arithmetic
The following SQL expressions do not function correctly with the gateway:
date + number
number + date date - number date1 - date2
Statements with the preceding expressions are sent to the SQL Server database without any translation. Since SQL Server does not support these date arithmetic functions, the statements return an error.
SQL Server IMAGE, TEXT and NTEXT Data Types
The following restrictions apply when using IMAGE, TEXT, and NTEXT data types:
■
■
■
■
An unsupported SQL function cannot be used in a SQL statement that accesses a column defined as SQL Server data type IMAGE, TEXT, or NTEXT.
You cannot use SQL*Plus to select data from a column defined as SQL Server data type IMAGE, TEXT, or NTEXT when the data is greater than 80 characters in length.
Oracle recommends using Pro*C or Oracle Call Interface to access such data in a
SQL Server database.
IMAGE
, TEXT, and NTEXT data cannot be read through pass-through queries.
If a SQL statement is accessing a table including an IMAGE, TEXT, or NTEXT column, the statement will be sent to SQL Server as two separate statements. One statement to access the IMAGE, TEXT or NTEXT column, and a second statement for the other columns in the original statement. This will result in two connections to
SQL Server due to a limitation in the Microsoft ODBC driver which only allows one statement for each connection, which can cause a hang depending on the sequence of SQL statements. If this happens, try issuing a commit and separating the statements in different transactions.
SQL Server Gateway Features and Restriction 2-15
Known Problems
The gateway does not support the PL/SQL function COLUMN_VALUE_LONG of the
DBMS_SQL
package.
See Also:
Appendix B, "Supported SQL Syntax and Functions"
for more information about restrictions on SQL syntax.
String Functions
If you concatenate numeric literals using the "||" or CONCAT operator when using the gateway to query a SQL Server database, the result is an arithmetic addition. For example, the result of the following statement is 18:
SQL> SELECT 9 || 9 FROM DUAL@MSQL;
The result is 99 when using Oracle to query an Oracle database.
Schema Names and PL/SQL
If you do not prefix a SQL Server database object with its schema name in a SQL statement within a PL/SQL block, the following error message occurs:
ORA-6550 PLS-201 Identifier table_name must be declared.
Change the SQL statement to include the schema name of the object.
Data Dictionary Views and PL/SQL
You cannot refer to data dictionary views in SQL statements that are inside a PL/SQL block.
Stored Procedures
Return values of stored procedures which return result sets are incorrect.
2-16 Oracle Database Gateway for Microsoft SQL Server User’s Guide
3
Case Studies
The following case studies for SQL Server demonstrate some of the features of the
Oracle Database Gateway. You can verify that the gateway is installed and operating correctly by using the demonstration files included in the distribution media.
The demonstration files are automatically copied to disk when the gateway is installed.
This chapter contains the following sections:
■
■
■
■
■
■
■
■
■
■
■
■
Case 3: Joining SQL Server Tables
Case 6: The Pass-Through Feature
Case 7: Executing Stored Procedures
Case Descriptions
The cases illustrate:
■
■
■
■
■
■
■
A simple query (Case 1)
A more complex query (Case 2)
Joining SQL Server tables (Case 3)
Write capabilities (Case 4)
A data dictionary query (Case 5)
The pass-through feature (Case 6)
Executing stored procedures (Case 7)
Case Studies 3-1
Installation Media Contents
Installation Media Contents
The installation media contains the following:
■
■
■
Demonstration files
One SQL script file that creates the demonstration tables and stored procedures in the SQL Server database
One SQL script file that drops the demonstration tables and stored procedures from the SQL Server database
Demonstration Files
After a successful gateway installation, use the demonstration files stored in the directory ORACLE_HOME\dg4msql\demo where ORACLE_HOME is the directory under which the gateway is installed. The directory contains the following demonstration files:
Demonstration Files
bldmsql.sql
case1.sql
case2.sql
case3.sql
case4a.sql
case4b.sql
case4c.sql
case5.sql
case6a.sql
case6b.sql
case7.sql
dropmsql.sql
Demonstration Requirements
The case studies assume these requirements have been met:
■
■
■
The gateway demonstration tables and stored procedures are installed in the SQL
Server database
The Oracle database has an account named SCOTT with a password of TIGER
The Oracle database has a database link called GTWLINK (set up as public or private to the user SCOTT) which connects the gateway to a SQL Server database as SCOTT with password TIGER2
For example, you can create the database link as follows:
SQL> CREATE DATABASE LINK GTWLINK CONNECT TO SCOTT
2 IDENTIFIED BY TIGER2 USING 'GTWSID';
■
Oracle Net Services is configured correctly and running
3-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Creating Demonstration Tables
Creating Demonstration Tables
The case studies are based on the GTW_EMP, GTW_DEPT, and GTW_SALGRADE tables and the stored procedures InsertDept and GetDept. If the demonstration tables and stored procedures have not been created in the SQL Server database, use the bldmsql.sql
script to create them. Enter the following:
> isql -USCOTT -PTIGER2 -ibldmsql.sql
The script creates the demonstration tables and stored procedures in the SQL Server database accordingly:
CREATE TABLE GTW_EMP (
EMPNO SMALLINT NOT NULL
ENAME VARCHAR(10),
JOB VARCHAR(9),
MGR SMALLINT,
HIREDATE DATETIME,
SAL NUMERIC(7,2),
COMM NUMERIC(7,2),
DEPTNO SMALLINT) go
CREATE TABLE GTW_DEPT (
DEPTNO SMALLINT NOT NULL,
DNAME VARCHAR(14),
LOC VARCHAR(13)) go
CREATE TABLE GTW_SALGRADE (
GRADE MONEY,
LOSAL NUMERIC(9,4),
HISAL NUMERIC(9,4)) go
DROP PROCEDURE InsertDept go
CREATE PROCEDURE InsertDept (@dno INTEGER,
@dname VARCHAR(14), @loc VARCHAR(13))
AS INSERT INTO GTW_DEPT VALUES (@dno, @dname, @loc) go
DROP PROCEDURE GetDept go
CREATE PROCEDURE GetDept (@dno INTEGER, @dname VARCHAR(14) OUTPUT)
AS SELECT @dname=DNAME FROM GTW_DEPT WHERE DEPTNO=@dno go
Demonstration Table Definitions
The following table definitions use information retrieved by the SQL*PLUS DESCRIBE command:
GTW_EMP
Name Null? Type
------------------------------- -------- ----
EMPNO NOT NULL NUMBER(5)
ENAME VARCHAR2(10)
Case Studies 3-3
Creating Demonstration Tables
JOB VARCHAR2(9)
MGR NUMBER(5)
HIREDATE DATE
SAL NUMBER(7,2)
COMM NUMBER(7,2)
DEPTNO NUMBER(5)
GTW_DEPT
Name Null? Type
------------------------------- -------- ----
DEPTNO NOT NULL NUMBER(5)
DNAME VARCHAR2(14)
LOC VARCHAR2(13)
GTW_SALGRADE
Name Null? Type
------------------------------- -------- ----
GRADE NUMBER(19,4)
LOSAL NUMBER(9,4)
HISAL NUMBER(9,4)
Demonstration Table Contents
The contents of the SQL Server tables are:
GTW_EMP
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
----- ----- --- --- -------- --- ---- ------
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7788 SCOTT ANALYST 7566 09-DEC-82 3000 20
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7876 ADAMS CLERK 7788 12-JAN-83 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
GTW_DEPT
DEPTNO DNAME LOC
----- -------------- --------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
GTW_SALGRADE
GRADE LOSAL HISAL
------ ------ -----
1 700 1200
2 1201 1400
3 1401 2000
3-4 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Case 4: Write Capabilities
4 2001 3000
5 3001 9999
Case 1: Simple Queries
Case 1 demonstrates the following:
■
■
A simple query
A simple query retrieving full date information
The first query retrieves all the data from GTW_DEPT and confirms that the gateway is working correctly. The second query retrieves all the data from GTW_EMP including the time portion of the hire date because the default date format was set to
DD-MON-YY HH24:MM:SS
for the session by an ALTER SESSION command.
Case 2: A More Complex Query
Case 2 demonstrates the following:
■
■
The functions SUM(expression) and NVL(expr1, expr2) in the SELECT list
The GROUP BY and HAVING clauses
This query retrieves the departments from GTW_EMP whose total monthly expenses are higher than $10,000.
Case 3: Joining SQL Server Tables
Case 3 demonstrates the following:
■
■
Joins between SQL Server tables
Subselects
The query retrieves information from three SQL Server tables and relates the employees to their department name and salary grade, but only for those employees earning more than the average salary.
Case 4: Write Capabilities
Case 4 is split into three cases and demonstrates the following:
■
■
■
DELETE Statement
Case 4a demonstrates bind values and subselect. All employees in department 20 and one employee, WARD, in department 30 are deleted.
UPDATE Statement
Case 4b provides an example of a simple UPDATE statement. In this example, employees are given a $100 a month salary increase.
Case Studies 3-5
Case 5: Data Dictionary Query
INSERT Statement
Case 4c is an example of a simple insert statement that does not provide information for all columns.
Case 5: Data Dictionary Query
Case 5 demonstrates data dictionary mapping. It retrieves all the tables and views that exist in the SQL Server database that begin with GTW.
Case 6: The Pass-Through Feature
Case 6 demonstrates the gateway pass-through feature which allows an application to send commands or statements to SQL Server.
This case demonstrates:
■
A pass-through UPDATE statement using bind variables
■
A pass-through SELECT statement
UPDATE Statement
Case 6a provides an example of a pass-through UPDATE statement with bind variables.
In this example, the salary for EMPNO 7934 is set to 4000.
SELECT Statement
Case 6b provides an example of a pass-through SELECT statement. The data that is returned from the SELECT statement is inserted into a local table at the Oracle database.
Case 7: Executing Stored Procedures
Case 7 demonstrates the gateway executing a stored procedure in the SQL Server database.
3-6 Oracle Database Gateway for Microsoft SQL Server User’s Guide
A
Data Type Conversion
This appendix contains the following section:
■
Data Type Conversion
The gateway converts SQL Server data types to Oracle data types as follows:
Table A–1 Data Type Conversions
SQL Server Oracle
BIGINT
BIGINT
IDENTITY
BINARY
BIT
CHAR
DATETIME
DECIMAL
DECIMAL
IDENTITY
FLOAT
IMAGE
INT
INT
IDENTITY
MONEY
NCHAR
NUMBER(19)
NUMBER(19)
Comment
RAW
NUMBER(3)
CHAR
DATE
NUMBER(p[,s])
-
NUMBER(p[,s])
-
-
-
Fractional parts of a second are truncated
FLOAT(53)
LONG RAW
NUMBER(10)
-
-
NTEXT
NVARCHAR
NVARCHAR(MAX)
NUMERIC
NUMERIC
IDENTITY
REAL
SMALLDATETIME
NUMBER(10)
NUMBER(19,4)
-
NCHAR
-
LONG
NVARCHAR
if Oracle DB Character Set = Unicode.
Otherwise, it is not supported
LONG
NUMBER(p[,s])
if Oracle DB Character Set = Unicode.
Otherwise, it is not supported
NUMBER(p[,s])
FLOAT(24)
DATE
-
-
Data Type Conversion A-1
Data Type Conversion
Table A–1 (Cont.) Data Type Conversions
SQL Server
SMALLMONEY
SMALLINT
SMALLINT
SYSNAME
IDENTITY
Oracle
NUMBER(10,4)
-
NUMBER(5)
-
NUMBER(5)
NVARCHAR
-
Comment
TEXT
TIMESTAMP
LONG
RAW
TINYINT
TINYINT
IDENTITY
VARBINARY
NUMBER(3)
NUMBER(3)
RAW
-
-
-
VARBINARY(MAX) LONG RAW
VARCHAR
VARCHAR(MAX)
VARCHAR2
LONG
-
-
XML LONG
A-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
B
Supported SQL Syntax and Functions
This appendix contains the following sections:
■
■
Supported SQL Statements
With a few exceptions, the gateway provides full support for Oracle DELETE, INSERT,
SELECT
, and UPDATE statements.
The gateway does not support Oracle data definition language (DDL) statements. No form of the Oracle ALTER, CREATE, DROP, GRANT, or TRUNCATE statements can be used. Instead, use the pass-through feature of the gateway if you need to use DDL statements against the SQL Server database.
Note: TRUNCATE
cannot be used in a pass-through statement.
DELETE
INSERT
SELECT
See Also:
Oracle Database Reference for a detailed descriptions of keywords, parameters, and options.
The DELETE statement is fully supported. However, only Oracle functions supported by SQL Server can be used.
See Also:
"Functions Supported by SQL Server" on page B-2 for a
list of supported functions.
The INSERT statement is fully supported. However, only Oracle functions supported by SQL Server can be used.
See Also:
"Functions Supported by SQL Server" on page B-2 for a
list of supported functions.
The SELECT statement is fully supported, with these exceptions:
Supported SQL Syntax and Functions B-1
Oracle Functions
■
■
■
■
CONNECT BY
condition
NOWAIT
START WITH
condition
WHERE CURRENT
OF
UPDATE
The UPDATE statement is fully supported. However, only Oracle functions supported by SQL Server can be used.
See Also:
"Functions Supported by SQL Server" on page B-2 for a
list of supported functions.
Oracle Functions
All functions are evaluated by the SQL Server database after the gateway has converted them to SQL Server SQL equivalents. The exception is the TO_DATE function, which is evaluated by the gateway.
Functions Not Supported by SQL Server
Oracle SQL functions with no equivalent function in SQL Server are not supported in
DELETE
, INSERT, or UPDATE statements, but are evaluated by the Oracle database if the statement is a SELECT statement. That is, the Oracle database performs post-processing of SELECT statements sent to the gateway.
If an unsupported function is used in a DELETE, INSERT, or UPDATE, statement, the following Oracle error occurs:
ORA-02070: database db_link_name does not support function in this context
Functions Supported by SQL Server
The gateway translates the following Oracle database functions in SQL statements to their equivalent SQL Server functions:
■
■
■
■
■
■
Arithmetic Operators
*
/
Oracle
+
-
*
/
SQL Server
+
-
B-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Oracle Functions
Comparison Operators
Oracle
=
>
<
>=
<=
<>, !=, ^=
IS NOT NULL
IS NULL
Pattern Matching
Oracle
LIKE
NOT LIKE
Group Functions
Oracle
AVG
COUNT
MAX
MIN
SUM
String Functions
Oracle
||, CONCAT
ASCII
CHR
INSTR
(with two arguments)
LENGTH
LOWER
LTRIM
RTRIM
SUBSTR
(second argument cannot be a negative number)
UPPER
<
>=
<=
<>
SQL Server
=
>
IS NOT NULL
IS NULL
SQL Server
LIKE
NOT LIKE
SQL Server
AVG
COUNT
MAX
MIN
SUM
SQL Server
+
(expression1 + expression2)
ASCII
CHAR
CHARINDEX
DATALENGTH
LOWER
LTRIM
RTRIM
SUBSTRING
UPPER
Supported SQL Syntax and Functions B-3
Oracle Functions
Other Functions
Oracle
ABS
CEIL
COS
EXP
FLOOR
LN
LOG
MOD
NOT NVL
NVL
POWER
ROUND
SIN
SQRT
TAN
SQL Server
ABS
CEILING
COS
EXP
FLOOR
LOG
LOG10
%
IS NOT NULL
IS NULL
POWER
ROUND
SIN
SQRT
TAN
Functions Supported by the Gateway
If an Oracle function has no equivalent function in SQL Server, the Oracle function is not translated into the SQL statement and must be post-processed if the SQL statement is a SELECT.
The gateway, however, does support the TO_DATE function equivalent in SQL Server, as follows:
TO_DATE(date_string | date_column)
Where: date_string is converted to a string with the following format:
yyyy-mm-dd hh:mi:ss.fff
Recommendation:
Supply the date string with the same format as the result (that is, yyyyy-mm-dd hh:mi:ss.fff).
date_column
is a column with a date data type. It is converted to a parameter with a timestamp data type.
B-4 Oracle Database Gateway for Microsoft SQL Server User’s Guide
C
Data Dictionary
The Oracle Database Gateway for SQL Server translates a query that refers to an
Oracle database data dictionary table into a query that retrieves the data from SQL
Server system tables. You perform queries on data dictionary tables over the database link in the same way you query data dictionary tables in the Oracle database. The gateway data dictionary is similar to the Oracle database data dictionary in appearance and use.
This appendix contains the following sections:
■
■
■
Gateway Data Dictionary Descriptions
Data Dictionary Support
The following paragraphs describe the Oracle Database Gateway for SQL Server data dictionary support.
SQL Server System Tables
SQL Server data dictionary information is stored in the SQL Server database as SQL
Server system tables. All SQL Server system tables have names prefixed with "sys".
The SQL Server system tables define the structure of a database. When you change data definitions, SQL Server reads and modifies the SQL Server system tables to add information about the user tables.
Accessing the Gateway Data Dictionary
Accessing a gateway data dictionary table or view is identical to accessing a data dictionary in an Oracle database. You issue a SQL SELECT statement specifying a database link. The Oracle database data dictionary view and column names are used to access the gateway data dictionary in an Oracle database. Synonyms of supported views are also acceptable. For example, the following statement queries the data dictionary table ALL_CATALOG to retrieve all table names in the SQL Server database:
SQL> SELECT * FROM "ALL_CATALOG"@MSQL;
When a data dictionary access query is issued, the gateway:
1.
Maps the requested table, view, or synonym to one or more SQL Server system table names. The gateway translates all data dictionary column names to their corresponding SQL Server column names within the query. If the mapping involves one SQL Server system table, the gateway translates the requested table
Data Dictionary C-1
Data Dictionary Support
2.
3.
4.
name to its corresponding SQL Server system table name within the query. If the mapping involves multiple SQL Server system tables, the gateway constructs a join in the query using the translated SQL Server system table names.
Sends the translated query to SQL Server.
Might convert the retrieved SQL Server data to give it the appearance of the
Oracle database data dictionary table.
Passes the data dictionary information from the translated SQL Server system table to the Oracle database.
Note:
The values returned when querying the gateway data dictionary might not be the same as the ones returned by the Oracle
SQL*Plus DESCRIBE command.
Direct Queries to SQL Server Tables
Queries issued directly to individual SQL Server system tables are allowed but they return different results because the SQL Server system table column names differ from those of the data dictionary view. Also, certain columns in an SQL Server system table cannot be used in data dictionary processing.
Supported Views and Tables
The gateway supports the following views and tables:
Supported Views and Table
ALL_CATALOG
ALL_CONS_COLUMNS
ALL_IND_COLUMNS
ALL_OBJECTS
ALL_TAB_COMMENTS
ALL_USERS
DBA_CATALOG
DBA_OBJECTS
DBA_TAB_COMMENTS
DICT_COLUMNS
DUAL
USER_CATALOG
USER_CONS_COLUMNS
USER_IND_COLUMNS
USER_OBJECTS
USER_TAB_COMMENTS
USER_USERS
Supported Views and Table
ALL_COL_COMMENTS
ALL_CONSTRAINTS
ALL_INDEXES
ALL_TAB_COLUMNS
ALL_TABLES
ALL_VIEWS
DBA_COL_COMMENTS
DBA_TAB_COLUMNS
DBA_TABLES
DICTIONARY
TABLE_PRIVILEGES
USER_COL_COMMENTS
USER_CONSTRAINTS
USER_INDEXES
USER_TAB_COLUMNS
USER_TABLES
USER_VIEWS
C-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Data Dictionary Mapping
No other Oracle database data dictionary tables or views are supported. If you use a view not on the list, you will receive the Oracle database error code for no more rows available.
Queries through the gateway of any data dictionary table or view beginning with
ALL_ can return rows from the SQL Server database even when access privileges for those SQL Server objects have not been granted. When querying an Oracle database with the Oracle data dictionary, rows are returned only for those objects you are permitted to access.
Data Dictionary Mapping
The tables in this section list Oracle data dictionary view names and the equivalent
SQL Server system tables used. A plus sign (+) indicates that a join operation is involved.
Table C–1 Oracle Data Dictionary View Names and SQL Server Equivalents
View Name
ALL_CATALOG
ALL_COL_COMMENTS
ALL_CONS_COLUMNS
ALL_CONSTRAINTS
ALL_IND_COLUMNS
ALL_INDEXES
ALL_OBJECTS
ALL_TAB_COLUMNS
ALL_TAB_COMMENTS
ALL_TABLES
ALL_USERS
SQL Server System Table Name
sysusers
+ sysobjects sysusers
+ sysobjects + syscolumns sp_pkeys
+ sp_fkeys sysusers
+ sysobjects + sysindexes + sysconstraints
+ sysreferences sysusers
+ sysindexes + syscolumns sysusers
+ sysindexes + sysobjects sysusers
+ sysobjects + sysindexes sysusers
+ sysobjects + syscolumns sysusers
+ sysobjects sysusers
+ sysobjects sysusers
ALL_VIEWS
DBA_CATALOG
DBA_COL_COMMENTS
DBA_OBJECTS
DBA_TABLES
DBA_TAB_COLUMNS
DBA_TAB_COMMENTS
DICT_COLUMNS
DICTIONARY
DUAL
TABLE_PRIVILEGES
USER_CATALOG
USER_COL_COMMENTS
USER_CONS_COLUMNS sysusers
+ sysobjects + syscomments sysusers
+ sysobjects sysusers
+ sysobjects + syscolumns sysusers
+ sysobjects + sysindexes sysusers
+ sysobjects sysusers
+ sysobjects + syscolumns sysusers
+ sysobjects sysobjects
+ syscolumns sysobjects sysusers sysprotects
+ sysusers + sysobjects sysusers
+ sysobjects sysusers
+ sysobjects + syscolumns sp_pkeys
+ sp_fkeys
Data Dictionary C-3
Gateway Data Dictionary Descriptions
Table C–1 (Cont.) Oracle Data Dictionary View Names and SQL Server Equivalents
View Name
USER_CONSTRAINTS
USER_IND_COLUMNS
USER_INDEXES
USER_OBJECTS
USER_TAB_COLUMNS
USER_TAB_COMMENTS
USER_TABLES
USER_USERS
USER_VIEWS
SQL Server System Table Name
sysusers
+ sysobjects + sysindexes + sysconstraints
+ sysreferences sysusers
+ sysindexes + syscolumns sysusers
+ sysindexes + sysobjects sysusers
+ sysobjects + sysindexes sysusers
+ sysobjects + syscolumns sysusers
+ sysobjects sysusers
+ sysobjects sysusers sysusers
+ sysobjects + syscomments
Default Column Values
There is a minor difference between the gateway data dictionary and a typical Oracle database data dictionary. The Oracle database columns that are missing in an SQL
Server system table are filled with zeros, spaces, null values, not-applicable values
(N.A.), or default values, depending on the column type.
Gateway Data Dictionary Descriptions
The gateway data dictionary tables and views provide the following information:
■
■
Name, data type, and width of each column
The contents of columns with fixed values
They are described here with information retrieved by an Oracle SQL*Plus DESCRIBE command. The values in the Null? column might differ from the Oracle database data dictionary tables and views. Any default value is shown to the right of an item, but this is not information returned by DESCRIBE.
Note:
The column width of some columns in the translated data dictionary tables would be different when the gateway connects to a SQL Server Version 7.0 database.
Table C–2 ALL_CATALOG
Name
OWNER
TABLE_NAME
TABLE_TYPE
-
-
-
Null?
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(5)
"TABLE" or
"VIEW"
C-4 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Gateway Data Dictionary Descriptions
Table C–3 ALL_COL_COMMENTS
Name
OWNER
TABLE_NAME
COLUMN_NAME
COMMENTS
-
-
-
-
Null?
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
-
Value
Table C–4 ALL_CONS_COLUMNS
Name
OWNER
CONSTRAINT_NAME
TABLE_NAME
COLUMN_NAME
POSITION
Null?
Type
-
-
-
-
NOT NULL VARCHAR2(30)
VARCHAR2(30)
VARCHAR2(30)
VARCHAR2(8192)
-
-
FLOAT(53)
-
-
-
Value
Table C–5 ALL_CONSTRAINTS
Name
OWNER
CONSTRAINT_NAME
CONSTRAINT_TYPE
TABLE_NAME
SEARCH_CONDITION
R_OWNER
R_CONSTRAINT_NAME
DELETE_RULE
STATUS
DEFERRABLE
DEFERRED
VALIDATED
GENERATED
BAD
RELY
LAST_CHANGE
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(256)
VARCHAR2(256)
VARCHAR2(1)
VARCHAR2(256)
VARCHAR2(1)
VARCHAR2(256)
VARCHAR2(256)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
DATE
Value
-
-
-
"C" or "P" or
"R" or "U"
-
-
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
-
NULL
Data Dictionary C-5
Gateway Data Dictionary Descriptions
Table C–6 ALL_IND_COLUMNS
Name
INDEX_OWNER
INDEX_NAME
TABLE_OWNER
TABLE_NAME
COLUMN_NAME
COLUMN_POSITION
COLUMN_LENGTH
DESCEND
Null?
Type
NOT NULL
NOT NULL
NOT NULL
VARCHAR2(30)
VARCHAR2(30)
VARCHAR2(30)
-
-
NOT NULL VARCHAR2(30)
VARCHAR2(8192)
-
-
NOT NULL
NOT NULL
FLOAT(53)
FLOAT(53)
VARCHAR2(4)
-
-
-
-
-
-
Value
Table C–7 ALL_INDEXES
Name
OWNER
INDEX_NAME
INDEX_TYPE
TABLE_OWNER
TABLE_NAME
TABLE_TYPE
UNIQUENESS
COMPRESSION
PREFIX_LENGTH
TABLESPACE_NAME
INI_TRANS
MAX_TRANS
INITIAL_EXTENT
NEXT_EXTENT
MIN_EXTENTS
MAX_EXTENTS
PCT_INCREASE
PCT_THRESHOLD
INCLUDE_COLUMN
FREELISTS
FREELIST_GROUPS
PCT_FREE
LOGGING
BLEVEL
-
-
-
-
-
-
Null?
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
C-6 Oracle Database Gateway for Microsoft SQL Server User’s Guide
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1) NULL
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR(7)
"TABLE" or
"CLUSTER"
VARCHAR2(1) NULL
VARCHAR2(1)
NUMBER
VARCHAR2(1)
NUMBER
NULL
0
NULL
0
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
0
0
0
0
0
0
0
0
0
0
0
NULL
0
Gateway Data Dictionary Descriptions
Table C–7 (Cont.) ALL_INDEXES
Name
LEAF_BLOCKS
DISTINCT_KEYS
AVG_LEAF_BLOCKS_PER_KEY
AVG_DATA_BLOCKS_PER_KEY
CLUSTERING_FACTOR
STATUS
NUM_ROWS
SAMPLE_SIZE
LAST_ANALYZED
DEGREE
INSTANCES
PARTITIONED
TEMPORARY
GENERATED
SECONDARY
BUFFER_POOL
USER_STATS
DURATION
PCT_DIRECT_ACCESS
ITYP_OWNER
ITYP_NAME
PARAMETERS
GLOBAL_STATS
DOMIDX_STATUS
DOMIDX_OPSTATUS
FUNCIDX_STATUS
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
NULL
NULL
NULL
0
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
0
NULL
0
0
NULL
0
0
0
Value
0
Type
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
DATE
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
NUMBER
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
Table C–8 ALL_OBJECTS
Name
OWNER
OBJECT_NAME
SUBOBJECT_NAME
OBJECT_ID
DATA_OBJECT_ID
-
-
-
-
-
Null?
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
NUMBER
-
NULL
NUMBER 0
Data Dictionary C-7
Gateway Data Dictionary Descriptions
Table C–8 (Cont.) ALL_OBJECTS
Name
OBJECT_TYPE
-
Null?
CREATED
LAST_DDL_TIME
TIMESTAMP
STATUS
TEMPORARY
GENERATED
SECONDARY
-
-
-
-
-
-
-
Type
VARCHAR2(9)
DATE
DATE
VARCHAR2(1)
VARCHAR2(5)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
Value
-
-
"TABLE" or
"VIEW" or
"INDEX" or
"PROCEDURE"
NULL
"VALID"
NULL
NULL
NULL
Table C–9 ALL_TAB_COLUMNS
Name
OWNER
TABLE_NAME
COLUMN_NAME
DATA_TYPE
DATA_TYPE_MOD
DATA_TYPE_OWNER
DATA_LENGTH
DATA_PRECISION
DATA_SCALE
NULLABLE
COLUMN_ID
DEFAULT_LENGTH
DATA_DEFAULT
NUM_DISTINCT
LOW_VALUE
HIGH_VALUE
DENSITY
NUM_NULLS
NUM_BUCKETS
LAST_ANALYZED
SAMPLE_SIZE
CHARACTER_SET_NAME
CHAR_COL_DEC_LENGTH
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
C-8 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(8)
-
VARCHAR2(1) NULL
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
NULL
-
0
-
-
-
"Y" or "N"
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NULL
0
0
0
0
0
NUMBER
DATE
NUMBER
VARCHAR2(1)
NUMBER
0
NULL
0
NULL
0
Gateway Data Dictionary Descriptions
Table C–9 (Cont.) ALL_TAB_COLUMNS
Name
GLOBAL_STATS
USER_STATS
AVG_COL_LEN
-
-
-
Null?
Type
VARCHAR2(1)
VARCHAR2(1)
NUMBER
Value
NULL
NULL
0
Table C–10 ALL_TAB_COMMENTS
Name
OWNER
TABLE_NAME
TABLE_TYPE
-
-
-
Null?
COMMENTS
-
Table C–11 ALL_TABLES
Name
OWNER
TABLE_NAME
TABLESPACE_NAME
CLUSTER_NAME
IOT_NAME
PCT_FREE
PCT_USED
INI_TRANS
MAX_TRANS
INITIAL_EXTENT
NEXT_EXTENT
MIN_EXTENTS
MAX_EXTENTS
PCT_INCREASE
FREELISTS
FREELIST_GROUPS
LOGGING
BACKED_UP
NUM_ROWS
BLOCKS
EMPTY_BLOCKS
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(5)
"TABLE" or
"VIEW"
VARCHAR2(1) NULL
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1) NULL
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
Value
NULL
NULL
0
0
0
0
0
0
0
0
0
0
0
NULL
NULL
0
0
0
Data Dictionary C-9
Gateway Data Dictionary Descriptions
Table C–11 (Cont.) ALL_TABLES
Name
AVG_SPACE
CHAIN_CNT
AVG_ROW_LEN
AVG_SPACE_FREELIST_BLOCKS
-
NUM_FREELIST_BLOCKS
-
DEGREE
INSTANCES
-
-
-
-
-
CACHE
TABLE_LOCK
SAMPLE_SIZE
LAST_ANALYZED
PARTITIONED
IOT_TYPE
TEMPORARY
SECONDARY
-
-
-
-
-
-
-
-
NESTED
BUFFER_POOL
ROW_MOVEMENT
GLOBAL_STATS
USER_STATS
DURATION
SKIP_CORRUPT
MONITORING
-
-
-
-
-
-
-
-
Null?
Table C–12 ALL_USERS
Name
USERNAME
USER_ID
CREATED
Null?
Type
-
NOT NULL
NOT NULL
VARCHAR2(256)
-
NUMBER(5)
DATE
-
-
Value
Table C–13 ALL_VIEWS
Name
OWNER
VIEW_NAME
TEXT_LENGTH
-
-
-
Null?
C-10 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
NUMBER
Value
0
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
0
NULL
NULL
NULL
NULL
NULL
0
NULL
NULL
NULL
NULL
0
0
0
Value
0
Type
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
NUMBER
DATE
VARCHAR2(1)
VARCHAR2(1)
VARHCAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARHCAR2(1)
VARCHAR2(1)
VARCHAR2(1)
Gateway Data Dictionary Descriptions
Table C–13 (Cont.) ALL_VIEWS
Name
TEXT
TYPE_TEXT_LENGTH
TYPE_TEXT
OID_TEXT_LENGTH
OID_TEXT
VIEW_TYPE_OWNER
VIEW_TYPE
-
-
-
-
-
-
-
Null?
Type Value
VARCHAR2(256)
-
NUMBER 0
VARCHAR2(1)
NUMBER
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
-
0
-
-
-
Table C–14 DBA_CATALOG
Name
OWNER
TABLE_NAME
TABLE_TYPE
-
-
-
Null?
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(5)
"TABLE" or
"VIEW"
Table C–15 DBA_COL_COMMENTS
Name
OWNER
TABLE_NAME
COLUMN_NAME
COMMENTS
-
-
-
-
Null?
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
Value
NULL
Table C–16 DBA_OBJECTS
Name
OWNER
OBJECT_NAME
SUBOBJECT_NAME
OBJECT_ID
DATA_OBJECT_ID
OBJECT_TYPE
CREATED
LAST_DDL_TIME
-
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
Value
NUMBER
-
NULL
NUMBER
VARCHAR2(9)
DATE
DATE
0
-
-
"TABLE" or
"VIEW" or
"INDEX" or
"PROCEDURE"
Data Dictionary C-11
Gateway Data Dictionary Descriptions
Table C–16 (Cont.) DBA_OBJECTS
Name
TIMESTAMP
STATUS
TEMPORARY
GENERATED
SECONDARY
-
-
-
-
-
Null?
Type
VARCHAR2(1)
VARCHAR2(5)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
Value
NULL
NULL
NULL
NULL
NULL
Table C–17 DBA_TAB_COLUMNS
Name
OWNER
TABLE_NAME
COLUMN_NAME
DATA_TYPE
DATA_TYPE_MOD
DATA_TYPE_OWNER
DATA_LENGTH
DATA_PRECISION
DATA_SCALE
NULLABLE
COLUMN_ID
DEFAULT_LENGTH
DATA_DEFAULT
NUM_DISTINCT
LOW_VALUE
HIGH_VALUE
DENSITY
NUM_NULLS
NUM_BUCKETS
LAST_ANALYZED
SAMPLE_SIZE
CHARACTER_SET_NAME
CHAR_COL_DEC_LENGTH
GLOBAL_STATS
USER_STATS
AVG_COL_LEN
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(8)
-
VARCHAR2(1)
Value
NULL
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
NULL
-
-
-
-
"Y" or "N"
0
VARCHAR2(1)
NUMBER
NUMBER
NULL
0
0
NUMBER
NUMBER
NUMBER
NUMBER
DATE
NUMBER
0
0
0
0
NULL
0
VARCHAR2(1)
NUMBER
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NULL
0
NULL
NULL
0
C-12 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Gateway Data Dictionary Descriptions
Table C–18 DBA_TAB_COMMENTS
Name
OWNER
TABLE_NAME
TABLE_TYPE
-
-
-
Null?
COMMENTS
-
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(5)
"TABLE" or
"VIEW"
VARCHAR2(1) NULL
Table C–19 DBA_TABLES
Name
OWNER
TABLE_NAME
TABLESPACE_NAME
CLUSTER_NAME
IOT_NAME
PCT_FREE
PCT_USED
INI_TRANS
MAX_TRANS
INITIAL_EXTENT
NEXT_EXTENT
MIN_EXTENTS
MAX_EXTENTS
PCT_INCREASE
FREELISTS
FREELIST_GROUPS
LOGGING
BACKED_UP
NUM_ROWS
BLOCKS
EMPTY_BLOCKS
AVG_SPACE
CHAIN_CNT
AVG_ROW_LEN
AVG_SPACE_FREELIST_BLOCKS
NUM_FREELIST_BLOCKS
DEGREE
INSTANCES
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
NUMBER
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1) NULL
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NUMBER
NULL
NULL
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
NULL
NULL
0
0
0
0
NULL
NULL
Data Dictionary C-13
Gateway Data Dictionary Descriptions
Table C–19 (Cont.) DBA_TABLES
Name
CACHE
TABLE_LOCK
SAMPLE_SIZE
LAST_ANALYZED
PARTITIONED
IOT_TYPE
TEMPORARY
SECONDARY
NESTED
BUFFER_POOL
ROW_MOVEMENT
GLOBAL_STATS
USER_STATS
DURATION
SKIP_CORRUPT
MONITORING
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(1)
VARCHAR2(1)
NUMBER
DATE
VARCHAR2(1)
VARCHAR2(1)
VARHCAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARHCAR2(1)
VARCHAR2(1)
VARCHAR2(1)
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
Value
NULL
NULL
0
NULL
NULL
NULL
NULL
NULL
Table C–20 DICT_COLUMNS
Name
TABLE_NAME
COLUMN_NAME
COMMENTS
-
-
-
Null?
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1) NULL
Table C–21 DICTIONARY
Name
TABLE_NAME
COMMENTS
-
-
Null?
Type
VARCHAR2(256)
-
VARCHAR2(1)
-
Value
Table C–22 DUAL
Name
DUMMY
Null?
NOT NULL
Type
VARCHAR2(1)
Value
"X"
C-14 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Gateway Data Dictionary Descriptions
Table C–23 TABLE_PRIVILEGES
Name
GRANTEE
OWNER
TABLE_NAME
GRANTOR
SELECT_PRIV
INSERT_PRIV
DELETE_PRIV
UPDATE_PRIV
REFERENCES_PRIV
ALTER_PRIV
INDEX_PRIV
CREATED
-
-
-
-
-
-
-
-
-
-
-
Null?
NOT NULL
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
"Y"
VARCHAR2(1)
VARCHAR2(1)
"A"
"Y"
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
DATE
-
"A"
"A"
"Y"
"Y"
Table C–24 USER_CATALOG
Name
TABLE_NAME
TABLE_TYPE
-
-
Null?
Type Value
VARCHAR2(256)
-
VARCHAR2(5)
"TABLE" or
"VIEW"
Table C–25 USER_COL_COMMENTS
Name Null?
TABLE_NAME
COLUMN_NAME
COMMENTS
-
-
-
Type
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
Value
NULL
Table C–26 USER_CONS_COLUMNS
Name
OWNER
CONSTRAINT_NAME
TABLE_NAME
COLUMN_NAME
POSITION
Null?
Type
-
NOT NULL
NOT NULL
VARCHAR2(30)
VARCHAR2(30)
-
NOT NULL VARCHAR2(30)
VARCHAR2(8192)
-
-
FLOAT(53)
-
-
-
Value
Data Dictionary C-15
Gateway Data Dictionary Descriptions
Table C–27 USER_CONSTRAINTS
Name
OWNER
CONSTRAINT_NAME
CONSTRAINT_TYPE
-
-
-
Null?
TABLE_NAME
SEARCH_CONDITION
R_OWNER
R_CONSTRAINT_NAME
DELETE_RULE
STATUS
DEFERRABLE
DEFERRED
VALIDATED
GENERATED
BAD
RELY
LAST_CHANGE
-
-
-
-
-
-
-
-
-
-
-
-
-
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1)
"R" or "P" or "U" or "C"
VARCHAR2(256)
-
VARCHAR2(1) NULL
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(1) NULL
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
NULL
NULL
NULL
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
DATE
NULL
NULL
NULL
-
NULL
Table C–28 USER_IND_COLUMNS
Name
INDEX_NAME
TABLE_NAME
COLUMN_NAME
COLUMN_POSITION
COLUMN_LENGTH
DESCEND
Null?
Type
-
NOT NULL
NOT NULL
VARCHAR2(30)
VARCHAR2(30)
-
NOT NULL
VARCHAR2(8192)
-
FLOAT(53)
-
-
-
NOT NULL FLOAT(53)
VARCHAR2(4)
-
-
Value
Table C–29 USER_INDEXES
Name
INDEX_NAME
INDEX_TYPE
TABLE_OWNER
TABLE_NAME
TABLE_TYPE
-
-
-
-
-
Null?
Type
VARCHAR2(256)
VARCHAR2(1)
VARCHAR2(256)
VARCHAR2(256)
VARCHAR2(7)
-
Value
NULL
-
-
"TABLE" or
"CLUSTER"
C-16 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Gateway Data Dictionary Descriptions
Table C–29 (Cont.) USER_INDEXES
Name
UNIQUENESS
COMPRESSION
PREFIX_LENGTH
TABLESPACE_NAME
INI_TRANS
MAX_TRANS
INITIAL_EXTENT
NEXT_EXTENT
MIN_EXTENTS
MAX_EXTENTS
PCT_INCREASE
PCT_THRESHOLD
INCLUDE_COLUMN
FREELISTS
FREELIST_GROUPS
PCT_FREE
LOGGING
BLEVEL
LEAF_BLOCKS
DISTINCT_KEYS
AVG_LEAF_BLOCKS_PER_KEY
AVG_DATA_BLOCKS_PER_KEY
CLUSTERING_FACTOR
STATUS
NUM_ROWS
SAMPLE_SIZE
LAST_ANALYZED
DEGREE
INSTANCES
PARTITIONED
TEMPORARY
GENERATED
SECONDARY
BUFFER_POOL
USER_STATS
DURATION
PCT_DIRECT_ACCESS
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
0
0
0
0
NULL
0
0
0
0
0
0
0
0
0
0
0
0
Value
NULL
NULL
0
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
0
0
NULL
0
0
NULL
NULL
NULL
0
Type
VARCHAR2(1)
VARCHAR2(1)
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
DATE
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARHCAR2(1)
NUMBER
Data Dictionary C-17
Gateway Data Dictionary Descriptions
Table C–29 (Cont.) USER_INDEXES
Name
ITYP_OWNER
ITYP_NAME
PARAMETERS
GLOBAL_STATS
DOMIDX_STATUS
DOMIDX_OPSTATUS
FUNCIDX_STATUS
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
Value
NULL
NULL
NULL
NULL
NULL
NULL
NULL
Table C–30 USER_OBJECTS
Name
OBJECT_NAME
SUBOBJECT_NAME
OBJECT_ID
DATA_OBJECT_ID
OBJECT_TYPE
-
-
-
-
-
Null?
CREATED
LAST_DDL_TIME
TIMESTAMP
STATUS
TEMPORARY
GENERATED
SECONDARY
-
-
-
-
-
-
-
Type
VARCHAR2(256)
-
Value
VARCHAR2(1)
NUMBER
-
NULL
NUMBER
VARCHAR2(9)
DATE
DATE
0
-
-
"TABLE" or
"VIEW" or
"INDEX" or
"PROCEDURE"
VARCHAR2(1)
VARCHAR2(5)
VARCHAR2(1)
NULL
"VALID"
NULL
VARCHAR2(1)
VARCHAR2(1)
NULL
NULL
Table C–31 USER_TAB_COLUMNS
Name Null?
TABLE_NAME
COLUMN_NAME
DATA_TYPE
DATA_TYPE_MOD
DATA_TYPE_OWNER
DATA_LENGTH
DATA_PRECISION
DATA_SCALE
-
-
-
-
-
-
-
-
C-18 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Type Value
VARCHAR2(256)
-
VARCHAR2(256)
-
VARCHAR2(8)
-
VARCHAR2(1) NULL
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
-
-
-
NULL
Gateway Data Dictionary Descriptions
Table C–31 (Cont.) USER_TAB_COLUMNS
Name
NULLABLE
COLUMN_ID
DEFAULT_LENGTH
DATA_DEFAULT
NUM_DISTINCT
LOW_VALUE
HIGH_VALUE
DENSITY
NUM_NULLS
NUM_BUCKETS
LAST_ANALYZED
SAMPLE_SIZE
CHARACTER_SET_NAME
CHAR_COL_DECL_LENGTH
GLOBAL_STATS
USER_STATS
AVG_COL_LEN
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(1)
NUMBER
NUMBER
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
DATE
NUMBER
VARCHAR2(1)
NUMBER
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NULL
0
NULL
NULL
0
0
0
0
0
0
Value
-
"Y" or "N"
0
NULL
0
NULL
0
Table C–32 USER_TAB_COMMENTS
Name
TABLE_NAME
TABLE_TYPE
-
-
Null?
COMMENTS
-
Type Value
VARCHAR2(256)
-
VARCHAR2(5)
"TABLE" or
"VIEW"
VARCHAR2(1) NULL
Table C–33 USER_TABLES
Name
TABLE_NAME
TABLESPACE_NAME
CLUSTER_NAME
IOT_NAME
PCT_FREE
PCT_USED
INI_TRANS
MAX_TRANS
-
-
-
-
-
-
-
-
Null?
Type
VARCHAR2(256)
-
Value
VARCHAR2(1) NULL
VARCHAR2(1)
VARCHAR2(1)
NULL
NULL
NUMBER
NUMBER
NUMBER
NUMBER
0
0
0
0
Data Dictionary C-19
Gateway Data Dictionary Descriptions
Table C–33 (Cont.) USER_TABLES
Name
INITIAL_EXTENT
NEXT_EXTENT
MIN_EXTENTS
MAX_EXTENTS
PCT_INCREASE
FREELISTS
FREELIST_GROUPS
LOGGING
BACKED_UP
NUM_ROWS
BLOCKS
EMPTY_BLOCKS
AVG_SPACE
CHAIN_CNT
AVG_ROW_LEN
AVG_SPACE_FREELIST_BLOCKS
NUM_FREELIST_BLOCKS
DEGREE
INSTANCES
CACHE
TABLE_LOCK
SAMPLE_SIZE
LAST_ANALYZED
PARTITIONED
IOT_TYPE
TEMPORARY
SECONDARY
NESTED
BUFFER_POOL
ROW_MOVEMENT
GLOBAL_STATS
USER_STATS
DURATION
SKIP_CORRUPT
MONITORING
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Null?
0
0
NULL
NULL
NULL
NULL
0
0
0
0
0
0
0
0
0
NULL
NULL
0
0
0
Value
0
NULL
NULL
NULL
NULL
NULL
NULL
NULL
NULL
0
NULL
NULL
NULL
NULL
NULL
Type
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
VARCHAR2(1)
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
NUMBER
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
NUMBER
DATE
VARCHAR2(1)
VARCHAR2(1)
VARHCAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
C-20 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Gateway Data Dictionary Descriptions
Table C–34 USER_USERS
Name
USERNAME
USER_ID
ACCOUNT_STATUS
LOCK_DATE
EXPIRY_DATE
DEFAULT_TABLESPACE
TEMPORARY_TABLESPACE
CREATED
INITIAL_RSRC_CONSUMER_GROUP
EXTERNAL_NAME
Null?
Type Value
-
-
-
-
-
-
-
-
NOT NULL
VARCHAR2(256)
-
NUMBER(5)
VARCHAR2(4)
-
"OPEN"
DATE
DATE
VARCHAR2(1)
VARCHAR2(1)
NULL
NULL
NULL
NULL
NOT NULL DATE
-
VARCHAR2(1)
VARCHAR2(1)
NULL
NULL
Table C–35 USER_VIEWS
Name
VIEW_NAME
TEXT_LENGTH
TEXT
TYPE_TEXT_LENGTH
TYPE_TEXT
OID_TEXT_LENGTH
OID_TEXT
VIEW_TYPE_OWNER
VIEW_TYPE
-
-
-
-
-
-
-
-
-
Null?
Type Value
VARCHAR2(256)
-
NUMBER 0
VARCHAR2(256)
-
NUMBER 0
VARCHAR2(1) NULL
NUMBER
VARCHAR2(1)
VARCHAR2(1)
VARCHAR2(1)
0
NULL
NULL
NULL
Data Dictionary C-21
Gateway Data Dictionary Descriptions
C-22 Oracle Database Gateway for Microsoft SQL Server User’s Guide
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:
■
■
■
Initialization Parameter File Syntax
Oracle Database Gateway for SQL Server Initialization Parameters
Initialization Parameter Description s
Initialization Parameter File Syntax
The syntax for the initialization parameter file is as follows:
1.
2.
3.
4.
5.
The file is a sequence of commands.
Each command should start on a separate line.
End of line is considered a command terminator (unless escaped with a backslash).
If there is a syntax error in an initialization parameter file, none of the settings take effect.
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:
a.
A string of characters that does not contain any backslashes, white space or double quotation marks (")
b.
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:
Initialization Parameters D-1
Oracle Database Gateway for SQL Server Initialization Parameters
*
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).
Oracle Database Gateway for SQL Server Initialization Parameters
This section lists all the initialization file parameters that can be set for the Oracle
Database Gateway for SQL Server. They are as follows:
■
■
■
■
■
■
■
■
■
D-2 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Initialization Parameter Description
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Initialization Parameter Description
The following sections describe all the initialization file parameters that can be set for gateways.
HS_CALL_NAME
Property
Default value
Range of values
Description
None
Not applicable
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.
Initialization Parameters D-3
Initialization Parameter Description
HS_DB_DOMAIN
Property
Default value
Range of values
Description
WORLD
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.
HS_DB_INTERNAL_NAME
Property
Default value
Range of values
Description
01010101
1
to 16 hexadecimal characters
HS_DB_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.
Property
Default value
Range of values
Description
HO
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.
HS_DESCRIBE_CACHE_HWM
Property
Default value
Range of values
Description
100
1
to 4000
D-4 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Initialization Parameter Description
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
Property
Default value
Range of values
Description
System-specific
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.
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.
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.
Initialization Parameters D-5
Initialization Parameter Description
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.
HS_LONG_PIECE_TRANSFER_SIZE
Property
Default value
Range of values
Description
64 KB
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.
HS_OPEN_CURSORS
Property
Default value
Range of values
Description
50
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.
HS_RPC_FETCH_REBLOCKING
Property
Default value
Range of values
Description
ON
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 to or higher than the value of HS_RPC_FETCH_SIZE
D-6 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Initialization Parameter Description 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
Property
Default value
Range of values
Description
50000
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.
HS_TIME_ZONE
Property
Default value for
'[+|-]hh:mm'
Range of values for
'[+|-]hh:mm'
Description
Derived from the NLS_TERRITORY initialization parameter
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
HS_TRANSACTION_MODEL
Property
Default Value
Range of Values
Description
COMMIT_CONFIRM
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:
Initialization Parameters D-7
Initialization Parameter Description
■
■
–
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
Property
Default value
Range of values
Description
None
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.
See Also:
Oracle Database Reference
HS_FDS_CONNECT_INFO
Property
Default Value
Range of Values
Description
None
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:
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
D-8 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Initialization Parameter Description
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
Property
Default Value
Range of Values
Description
None
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.
HS_FDS_PROC_IS_FUNC
Property
Default Value
Range of Values
Description
FALSE
TRUE
, FALSE
Enables return values from functions. By default, all stored procedures and functions do not return a return value to the user.
Note:
If you set this initialization parameter, you must change the syntax of the procedure execute statement for all existing stored procedures to handle return values.
HS_FDS_RECOVERY_ACCOUNT
Property
Default Value
Description
RECOVER
Initialization Parameters D-9
Initialization Parameter Description
Property
Range of values
Description
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.
HS_FDS_RECOVERY_PWD
Property
Default Value
Range of values
Description
RECOVER
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.
HS_FDS_RESULTSET_SUPPORT
Property
Default Value
Range of Values
Description
FALSE
TRUE
, FALSE
Enables result sets to be returned from stored procedures. By default, all stored procedures do not return a result set to the user.
Note:
If you set this initialization parameter, you must do the following:
■
■
Change the syntax of the procedure execute statement for all existing stored procedures, to handle result sets
Work in the sequential mode of Heterogeneous Services
HS_FDS_TRACE_LEVEL
Property
Default Value
Range of values
Description
OFF
OFF
, ON, DEBUG
Specifies whether error tracing is turned on or off for gateway connectivity.
The following values are valid:
D-10 Oracle Database Gateway for Microsoft SQL Server User’s Guide
Initialization Parameter Description
■
■
■
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
Property
Default Value
Range of Values
Description
HS_TRANSACTION_LOG
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.
HS_FDS_REPORT_REAL_AS_DOUBLE
Property
Default Value
Range of Values
Description
FALSE
TRUE
, FALSE
Enables Oracle Database Gateway for SQL Server to treat SINGLE FLOAT
PRECISION
fields as DOUBLE FLOAT PPRECISION fields.
HS_FDS_FETCH_ROWS
Property
Default Value
Range of Values
Syntax
Description
100
Any integer between 1 and 1000
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.
Initialization Parameters D-11
Initialization Parameter Description
D-12 Oracle Database Gateway for Microsoft SQL Server User’s Guide
A
B
C
character sets
COMMIT
Cursor loops
D
Data dictionary
Data type
Index
DELETE statement, 3-5, B-1, B-2
demonstration build SQL script, 3-2
Demonstration tables build SQL script, 3-3
describe cache high water mark
E
Error messages
Errors
Executing Stored Procedures, 3-6
F
fetch array size, with HS_FDS_FETCH_ROWS, D-11
G
Gateway
pass-through feature, 2-1, 2-12
Index-1
supported functions, B-1 supported SQL syntax, B-1
globalization support
H
Heterogeneous Services
defining maximum number of open cursors, D-6 optimizing data transfer, D-6
specifying cache high water mark, D-5
tuning internal data buffering, D-7
tuning LONG data transfer, D-6
HS_CALL_NAME initialization parameter, D-3
HS_DB_NAME initialization parameter, D-4
HS_DESCRIBE_CACHE_HWM initialization parameter, D-5
HS_FDS_DEFAULT_OWNER initialization parameter, D-9
HS_FDS_FETCH_ROWS parameter, D-11
HS_FDS_PROC_IS_FUNC initialization parameter, D-9
HS_FDS_RECOVERY_PWD initialization parameter, D-11
HS_FDS_RESULTSET_SUPPORT initialization parameter, D-10
HS_FDS_TRACE_LEVEL initialization parameter, D-10
HS_FDS_TRANSACTION_LOG initialization parameter, D-11
HS_LANGUAGE initialization parameter, D-5
HS_LONG_PIECE_TRANSFER_SIZE initialization parameter, D-6
HS_OPEN_CURSORS initialization parameter, D-6
HS_RPC_FETCH_REBLOCKING initialization parameter, D-6
HS_RPC_FETCH_SIZE initialization parameter, D-7
HS_TIME_ZONE initialization parameter, D-7
I
IFILE initialization parameter, D-8
Initialization parameter file
INSERT statement, 3-6, B-1, B-2
K
L
Index-2
M
N
O
P
parameters gateway initialization file
Passing commands to database, 2-11
R
remote functions
referenced in SQL statements, D-3
ROLLBACK
S
SELECT statement, 3-6, B-1, C-1
Stored procedures in SQL Server, 2-2
T
transactional capability, 2-11 transactional integrity, 2-11
U
UPDATE statement, 2-13, 3-5, 3-6, B-2
V
VARBINARY data type, 2-15, A-2
W
Index-3
Index-4
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Key features
Access SQL Server data from Oracle
Pass SQL Server commands to SQL Server database
Perform distributed queries
Copy SQL Server data to Oracle
Supports stored procedures
Supports user-defined functions
Supports result sets
Provides data type conversions
Provides a transparent interface for accessing SQL Server data
Can be installed on a separate machine from Oracle or SQL Server
Frequently asked questions
It's a software component that allows Oracle client applications to access data stored in a SQL Server database.
It allows you to access data, pass commands, perform distributed queries, and copy data between Oracle and SQL Server databases. It also supports stored procedures, user-defined functions, and result sets. The gateway provides data type conversions and runs on a separate machine if needed.
Use PL/SQL statements to execute a stored procedure. Make sure the stored procedure has the necessary access privileges for the gateway's user.
