Oracle Database Gateway for SQL Server User’s Guide · products, and services from third parties. Oracle Corporation and its affiliates are not responsible for and expressly disclaim

Oracle® Database Gateway for SQL ServerUser’s Guide,

12c Release 1 (12.1)

E17935-08

April 2017

Oracle Database Gateway for SQL Server User's Guide, 12c Release 1 (12.1)

E17935-08

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iii

Contents

Preface ................................................................................................................................................................ ix

Audience...................................................................................................................................................... ixDocumentation Accessibility .................................................................................................................... ixRelated Documentation.............................................................................................................................. xConventions ................................................................................................................................................. x

1 Introduction

Overview .................................................................................................................................................... 1-1Heterogeneous Services Technology.................................................................................................... 1-1Oracle Database Gateways ..................................................................................................................... 1-2

2 SQL Server Gateway Features and Restriction

Using the Pass-Through Feature ........................................................................................................... 2-1Executing Stored Procedures and Functions....................................................................................... 2-2CHAR Semantics ...................................................................................................................................... 2-2Multi-byte Character Sets Ratio Suppression .................................................................................... 2-2IPv6 Support.............................................................................................................................................. 2-3Gateway Session IDLE Timeout ........................................................................................................... 2-3Remote User-defined Function Support.............................................................................................. 2-3

Return Values and Stored Procedures ............................................................................................ 2-3Result Sets and Stored Procedures .................................................................................................. 2-4

Database Compatibility Issues for SQL Server.................................................................................. 2-7Implicit Transactions (Chained Mode) ........................................................................................... 2-7Column Definitions............................................................................................................................ 2-7Naming Rules ..................................................................................................................................... 2-7Data Types........................................................................................................................................... 2-8Queries................................................................................................................................................. 2-9Locking ............................................................................................................................................. 2-10

Known Restrictions .............................................................................................................................. 2-10Multiple Open Statements ............................................................................................................. 2-11Transactional Integrity .................................................................................................................. 2-11Transaction Capability .................................................................................................................. 2-11COMMIT or ROLLBACK in PL/SQL Cursor Loops Closes Open Cursors .......................... 2-12Stored Procedures ........................................................................................................................... 2-12Pass-Through Feature..................................................................................................................... 2-12

iv

DDL Statements............................................................................................................................... 2-12SQL Syntax ....................................................................................................................................... 2-13Functions .......................................................................................................................................... 2-14SQL*Plus COPY Command with Lowercase Table Names...................................................... 2-15Database Links................................................................................................................................. 2-15CALLBACK links ............................................................................................................................ 2-15

Known Problems ................................................................................................................................... 2-15Encrypted Format Login ............................................................................................................... 2-15Date Arithmetic ............................................................................................................................... 2-16SQL Server IMAGE, TEXT and NTEXT Data Types.................................................................. 2-16String Functions............................................................................................................................... 2-16Schema Names and PL/SQL......................................................................................................... 2-16Data Dictionary Views and PL/SQL............................................................................................ 2-16Stored Procedures ........................................................................................................................... 2-17

3 Case Studies

Case Descriptions ..................................................................................................................................... 3-1Installation Media Contents................................................................................................................... 3-2Demonstration Files................................................................................................................................. 3-2Demonstration Requirements................................................................................................................ 3-2Creating Demonstration Tables ............................................................................................................ 3-3

Demonstration Table Definitions..................................................................................................... 3-3Demonstration Table Contents ........................................................................................................ 3-4

Case 1: Simple Queries............................................................................................................................ 3-5Case 2: A More Complex Query ............................................................................................................ 3-5Case 3: Joining SQL Server Tables ....................................................................................................... 3-5Case 4: Write Capabilities....................................................................................................................... 3-5

DELETE Statement............................................................................................................................. 3-5UPDATE Statement ........................................................................................................................... 3-5INSERT Statement.............................................................................................................................. 3-6

Case 5: Data Dictionary Query .............................................................................................................. 3-6Case 6: The Pass-Through Feature ........................................................................................................ 3-6

UPDATE Statement ........................................................................................................................... 3-6SELECT Statement ............................................................................................................................. 3-6

Case 7: Executing Stored Procedures .................................................................................................... 3-6

A Data Type Conversion

Data Type Conversion............................................................................................................................ A-1

B Supported SQL Syntax and Functions

Supported SQL Statements ................................................................................................................... B-1DELETE .............................................................................................................................................. B-1INSERT ............................................................................................................................................... B-1SELECT............................................................................................................................................... B-1UPDATE ............................................................................................................................................. B-2

Oracle Functions ...................................................................................................................................... B-2

v

Functions Not Supported by SQL Server ...................................................................................... B-2Functions Supported by SQL Server .............................................................................................. B-2Functions Supported by the Gateway............................................................................................ B-4

C Data Dictionary

Data Dictionary Support........................................................................................................................ C-1SQL Server System Tables ............................................................................................................... C-1Accessing the Gateway Data Dictionary ....................................................................................... C-1Direct Queries to SQL Server Tables .............................................................................................. C-2Supported Views and Tables........................................................................................................... C-2

Data Dictionary Mapping...................................................................................................................... C-3Default Column Values .................................................................................................................... C-4

Gateway Data Dictionary Descriptions .............................................................................................. C-4

D Initialization Parameters

Initialization Parameter File Syntax .................................................................................................... D-1Oracle Database Gateway for SQL Server Initialization Parameters ........................................... D-2Initialization Parameter Description ................................................................................................... D-3

HS_CALL_NAME ............................................................................................................................ D-3HS_DB_DOMAIN ............................................................................................................................ D-4HS_DB_INTERNAL_NAME .......................................................................................................... D-4HS_DB_NAME ................................................................................................................................. D-4HS_DESCRIBE_CACHE_HWM .................................................................................................... D-5HS_LANGUAGE ............................................................................................................................. D-5HS_LONG_PIECE_TRANSFER_SIZE ......................................................................................... D-6HS_OPEN_CURSORS .................................................................................................................... D-6HS_RPC_FETCH_REBLOCKING ................................................................................................ D-7HS_RPC_FETCH_SIZE ................................................................................................................... D-7HS_TIME_ZONE .............................................................................................................................. D-7HS_TRANSACTION_MODEL ....................................................................................................... D-8IFILE ................................................................................................................................................... D-8HS_FDS_TIMESTAMP_MAPPING................................................................................................ D-9HS_FDS_DATE_MAPPING ............................................................................................................ D-9HS_FDS_CONNECT_INFO ............................................................................................................ D-9HS_FDS_PROC_IS_FUNC............................................................................................................. D-10HS_FDS_RECOVERY_ACCOUNT .............................................................................................. D-10HS_FDS_RECOVERY_PWD.......................................................................................................... D-11HS_FDS_REPORT_REAL_AS_DOUBLE .................................................................................... D-11HS_FDS_RESULTSET_SUPPORT ................................................................................................ D-11HS_FDS_TRACE_LEVEL............................................................................................................... D-11HS_FDS_TRANSACTION_LOG .................................................................................................. D-12HS_FDS_FETCH_ROWS................................................................................................................ D-12HS_IDLE_TIMEOUT ...................................................................................................................... D-12HS_NLS_LENGTH_SEMANTICS................................................................................................ D-12HS_KEEP_REMOTE_COLUMN_SIZE........................................................................................ D-13HS_FDS_REMOTE_DB_CHARSET ............................................................................................. D-13

vi

HS_FDS_SUPPORT_STATISTICS ................................................................................................ D-14HS_FDS_RSET_RETURN_ROWCOUNT.................................................................................... D-14HS_FDS_SQLLEN_INTERPRETATION ..................................................................................... D-14HS_FDS_ARRAY_EXEC ................................................................................................................ D-15

Index

vii

viii

List of Tables

2–1 Restricted DDL Statements.................................................................................................... 2-12A–1 Data Type Mapping and Restrictions .................................................................................... A-1C–1 Oracle Data Dictionary View Names and SQL Server Equivalents .................................. C-3C–2 ALL_CATALOG ....................................................................................................................... C-4C–3 ALL_COL_COMMENTS ......................................................................................................... C-5C–4 ALL_CONS_COLUMNS ......................................................................................................... C-5C–5 ALL_CONSTRAINTS............................................................................................................... C-5C–6 ALL_IND_COLUMNS............................................................................................................. C-6C–7 ALL_INDEXES .......................................................................................................................... C-6C–8 ALL_OBJECTS........................................................................................................................... C-7C–9 ALL_TAB_COLUMNS............................................................................................................. C-8C–10 ALL_TAB_COMMENTS.......................................................................................................... C-9C–11 ALL_TABLES............................................................................................................................. C-9C–12 ALL_USERS ............................................................................................................................. C-10C–13 ALL_VIEWS............................................................................................................................. C-11C–14 DBA_CATALOG..................................................................................................................... C-11C–15 DBA_COL_COMMENTS....................................................................................................... C-11C–16 DBA_OBJECTS ........................................................................................................................ C-11C–17 DBA_TAB_COLUMNS .......................................................................................................... C-12C–18 DBA_TAB_COMMENTS....................................................................................................... C-13C–19 DBA_TABLES.......................................................................................................................... C-13C–20 DICT_COLUMNS ................................................................................................................... C-14C–21 DICTIONARY.......................................................................................................................... C-14C–22 DUAL........................................................................................................................................ C-15C–23 TABLE_PRIVILEGES ............................................................................................................. C-15C–24 USER_CATALOG ................................................................................................................... C-15C–25 USER_COL_COMMENTS..................................................................................................... C-15C–26 USER_CONS_COLUMNS ..................................................................................................... C-15C–27 USER_CONSTRAINTS .......................................................................................................... C-16C–28 USER_IND_COLUMNS......................................................................................................... C-16C–29 USER_INDEXES...................................................................................................................... C-17C–30 USER_OBJECTS ...................................................................................................................... C-18C–31 USER_TAB_COLUMNS ........................................................................................................ C-18C–32 USER_TAB_COMMENTS ..................................................................................................... C-19C–33 USER_TABLES ........................................................................................................................ C-20C–34 USER_USERS........................................................................................................................... C-21C–35 USER_VIEWS .......................................................................................................................... C-21

ix

Preface

This manual describes the Oracle Database Gateway for SQL Server, which enablesOracle client applications to access SQL Server data through Structured QueryLanguage (SQL). The gateway, with the Oracle database, creates the appearance thatall data resides on a local Oracle database, even though the data can be widelydistributed.

This preface covers the following topics:

■ Audience

■ Documentation Accessibility

■ Related Documentation

■ Conventions

AudienceThis manual is intended for Oracle database administrators who perform thefollowing tasks:

■ Installing and configuring the Oracle Database Gateway for SQL Server

■ Diagnosing gateway errors

■ Using the gateway to access SQL Server data

Documentation AccessibilityFor information about Oracle's commitment to accessibility, visit the OracleAccessibility Program website athttp://www.oracle.com/pls/topic/lookup?ctx=acc&id=docacc.

Access to Oracle SupportOracle customers that have purchased support have access to electronic supportthrough My Oracle Support. For information, visithttp://www.oracle.com/pls/topic/lookup?ctx=acc&id=info or visithttp://www.oracle.com/pls/topic/lookup?ctx=acc&id=trs if you are hearingimpaired.

Note: You should understand the fundamentals of OracleDatabase Gateways and the Microsoft Windows operating systembefore using this guide to install or administer the gateway.

x

Related DocumentationFor more information, see the following documents:

■ Oracle Database New Features Guide

■ Oracle Call Interface Programmer's Guide

■ Oracle Database Administrator's Guide

■ Oracle Database Development 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 User'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, whichis installed by default when you install Oracle. Refer to Oracle Database Sample Schemasfor information on how these schemas were created and how you can use themyourself.

Printed documentation is available for sale in the Oracle Store at

https://shop.oracle.com/

ConventionsThe following text conventions are used in this document:

Convention Meaning

boldface Boldface type indicates graphical user interface elements associatedwith an action, or terms defined in text or the glossary.

italic Italic type indicates book titles, emphasis, or placeholder variables forwhich you supply particular values.

monospace Monospace type indicates commands within a paragraph, URLs, codein examples, text that appears on the screen, or text that you enter.

1

Introduction 1-1

1 Introduction

This chapter introduces the challenge faced by organizations when running severaldifferent database systems. It briefly covers Heterogeneous Services, the technologythat the Oracle Database Gateway for SQL Server is based on.

To get a good understanding of generic gateway technology, Heterogeneous Services,and how Oracle Database Gateways fit in the picture, reading Oracle DatabaseHeterogeneous Connectivity User's Guide first is highly recommended.

This chapter contains the following sections:

■ Overview

■ Heterogeneous Services Technology

■ Oracle Database Gateways

OverviewHeterogeneous data access is a problem that affects a lot of companies. A lot ofcompanies run several different database systems. Each of these systems stores dataand has a set of applications that run against it. Consolidation of this data in onedatabase system is often hard-in large part because many of the applications that runagainst one database may not have an equivalent that runs against another. Until suchtime as migration to one consolidated database system is made feasible, it is necessaryfor the various heterogeneous database systems to interoperate.

Oracle Database Gateways provide the ability to transparently access data residing ina non-Oracle system from an Oracle environment. This transparency eliminates theneed for application developers to customize their applications to access data fromdifferent non-Oracle systems, thus decreasing development efforts and increasing themobility of the application. Applications can be developed using a consistent Oracleinterface for both Oracle and SQL Server.

Gateway technology is composed of two parts: a component that has the generictechnology to connect to a non-Oracle system, which is common to all the non-Oraclesystems, called Heterogeneous Services, and a component that is specific to thenon-Oracle system that the gateway connects to. Heterogeneous Services, inconjunction with the Oracle Database Gateway agent, enables transparent access tonon-Oracle systems from an Oracle environment.

Heterogeneous Services TechnologyHeterogeneous Services provides the generic technology for connecting to non-Oraclesystems. As an integrated component of the database, Heterogeneous Services can

Oracle Database Gateways

1-2 Oracle Database Gateway for SQL Server User's Guide

exploit features of the database, such as the powerful SQL parsing and distributedoptimization capabilities.

Heterogeneous Services extend the Oracle SQL engine to recognize the SQL andprocedural capabilities of the remote non-Oracle system and the mappings required toobtain necessary data dictionary information. Heterogeneous Services provides twotypes of translations: the ability to translate Oracle SQL into the proper dialect of thenon-Oracle system as well as data dictionary translations that displays the metadata ofthe non-Oracle system in the local format. For situations where no translations areavailable, native SQL can be issued to the non-Oracle system using the pass-throughfeature of Heterogeneous Services.

Heterogeneous Services also maintains the transaction coordination between Oracleand the remote non-Oracle system, such as providing the two-phase commit protocolto ensure distributed transaction integrity, even for non-Oracle systems that do notnatively support two-phase commit.

Oracle Database GatewaysThe capabilities, SQL mappings, data type conversions, and interface to the remotenon-Oracle system are contained in the gateway. The gateway interacts withHeterogeneous Services to provide the transparent connectivity between Oracle andnon-Oracle systems.

The gateway can be installed on any machine independent of the Oracle or non-Oracledatabase. It can be the same machine as the Oracle database or on the same machine asthe SQL Server database or on a third machine as a standalone.

See Also: Oracle Database Heterogeneous Connectivity User's Guidefor more information about Heterogeneous Services.

2

SQL Server Gateway Features and Restriction 2-1

2 SQL Server Gateway Features andRestriction

After the gateway is installed and configured, you can use the gateway to access SQLServer data, pass SQL Server commands from applications to the SQL Server database,perform distributed queries, and copy data.


■ Using the Pass-Through Feature

■ Executing Stored Procedures and Functions

■ CHAR Semantics

■ Multi-byte Character Sets Ratio Suppression

■ IPv6 Support

■ Remote User-defined Function Support

■ Database Compatibility Issues for SQL Server

■ Known Restrictions

■ Known Problems

Using the Pass-Through FeatureThe gateway can pass SQL Server commands or statements from the application to theSQL Server database using the DBMS_HS_PASSTHROUGH package.

Use the DBMS_HS_PASSTHROUGH package in a PL/SQL block to specify the statement tobe passed to the SQL Server database, as follows:

DECLAREnum_rows INTEGER;

BEGINnum_rows := DBMS_HS_PASSTHROUGH.EXECUTE_IMMEDIATE@MSQL('command');

END;/

Where command cannot be one of the following:

■ BEGIN TRANSACTION

■ COMMIT

■ ROLLBACK

■ SAVE

Executing Stored Procedures and Functions


■ SHUTDOWN

■ RELEASE

■ SAVEPOINT

■ CONNECT

■ SQL Server tool commands

The DBMS_HS_PASSTHROUGH package supports passing bind values and executingSELECT statements.

Executing Stored Procedures and FunctionsUsing the procedural feature, the gateway can execute stored procedures that aredefined in the SQL Server database. It is not necessary to relink the gateway or definethe procedure to the gateway, but the procedure's access privileges must permit accessby the user that the gateway is logging in as.

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

CHAR SemanticsThis feature allows the gateway to optionally run in CHAR Semantics mode. Ratherthan always describing SQL Server CHAR columns as CHAR(n BYTE), this featuredescribes them as CHAR(n CHAR) and VARCHAR(n CHAR). The concept is similar toOracle database CHAR Semantics. You need to specify HS_NLS_LENGTH_SEMANTICS=CHARgateway parameter to activate this option. Refer to Appendix D for more detail.

Multi-byte Character Sets Ratio SuppressionThis feature optionally suppresses the ratio expansion from SQL Server database toOracle database involving multi-byte character set. By default, Oracle gatewaysassume the worst ratio to prevent data being truncated or insufficient buffer sizesituation. However, if you have specific knowledge of your SQL Server database anddo not want the expansion to occur, you can specify HS_KEEP_REMOTE_COLUMN_SIZEparameter to suppress the expansion. Refer to Appendix D for more detail.

Note: TRUNCATE cannot be used in a pass-through statement.

See Also: Oracle Database PL/SQL Packages and Types Reference andChapter 3, Features of Oracle Database Gateways, of OracleDatabase Heterogeneous Connectivity User's Guide for moreinformation about the DBMS_HS_PASSTHROUGH package.

See Also: Oracle Database Heterogeneous Connectivity User's Guidefor more information about executing stored procedures.

Remote User-defined Function Support


IPv6 SupportBesides full IPv6 support between Oracle databases and the gateway, IPv6 is alsosupported between this gateway and SQL Server database. Refer to the HS_FDS_CONNECT_INFO parameter in Appendix D for more detail.

Gateway Session IDLE TimeoutYou can optionally choose to terminate long idle gateway sessions automatically withthe gateway parameter HS_IDLE_TIMEOUT. Specifically, when a gateway session is idlefor more than the specified time limit, the gateway session is terminated with anypending update rolled back. Refer to the HS_IDLE_TIMEOUT parameter in Appendix Dfor more detail.

Remote User-defined Function SupportUser-defined functions in a remote non-Oracle database can be used in SQLstatements.

Return Values and Stored ProceduresBy 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 value to TRUE.

In the following example, the employee name JOHN SMYTHE is passed to the SQL Serverstored procedure REVISE_SALARY. The stored procedure retrieves the salary value fromthe SQL Server database to calculate a new yearly salary for JOHN SMYTHE. The revisedsalary returned in RESULT is used to update EMP in a table of an Oracle database:

DECLAREINPUT VARCHAR2(15);RESULT NUMBER(8,2);

BEGININPUT := '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 fromPL/SQL data types.

See Also: Oracle Database Heterogeneous Connectivity User's Guidefor more information about executing user-defined functions on anon-Oracle database.

See Also: Appendix D, "Initialization Parameters" forinformation about both editing the initialization parameter file andthe HS_FDS_PROC_IS_FUNC parameter.

Note: If you set the HS_FDS_PROC_IS_FUNC gateway initializationparameter to TRUE, you must change the syntax of the procedureexecute statement for all existing stored procedures.



Result Sets and Stored ProceduresThe Oracle Database Gateway for SQL Server provides support for stored procedureswhich return result sets.

By default, all stored procedures and functions do not return a result set to the user. Toenable result sets, set the HS_FDS_RESULTSET_SUPPORT parameter value to TRUE.

When accessing stored procedures with result sets through the Oracle DatabaseGateway for SQL Server, you will be in the sequential mode of HeterogeneousServices.

The Oracle Database Gateway for SQL Server returns the following information toHeterogeneous Services during procedure description:

■ All the input arguments of the remote stored procedure

■ None of the output arguments

■ One out argument of type ref cursor (corresponding to the first result set returnedby 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 setreturned 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 orderin which they were placed on the wire

■ On execution of a stored procedure, all result sets returned by a previouslyexecuted stored procedure will be closed (regardless of whether the data has beencompletely retrieved or not)

In the following example, the SQL Server stored procedure is executed to fetch thecontents of the emp and dept tables from SQL Server:

create procedure REFCURPROC (@arg1 varchar(255), @arg2 varchar(255) output)asselect @arg2 = @arg1select * from EMPselect * from DEPTgo

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.

See Also: Appendix D, "Initialization Parameters" for informationabout both editing the initialization parameter file and the HS_FDS_RESULTSET_SUPPORT parameter. For further information aboutOracle support for result sets in non-Oracle databases see OracleDatabase Heterogeneous Connectivity User's Guide.

Note: If you set the HS_FDS_RESULTSET_SUPPORT gatewayinitialization parameter to TRUE, then you must change the syntaxof the procedure execute statement for all existing storedprocedures, else errors will occur.



OCI Program Fetching from Result Sets in Sequential ModeThe following example shows OCI program fetching from result sets in sequentialmode:

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);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 theremote stored procedure */

/* Repeat execution of get_next_result_set to get the output arguments */

PL/SQL Program Fetching from Result Sets in Sequential ModeAssume that the table loc_emp is a local table exactly like the SQL Server emp table. Thesame assumption applies for loc_dept. The table outargs has columns correspondingto the out arguments of the SQL Server stored procedure.

create table outargs (outarg varchar2(255), retval number);

create or replace package rcpackage istype RCTYPE is ref cursor;

end rcpackage;/

declarerc1 rcpackage.rctype;rec1 loc_emp%rowtype;rc2 rcpackage.rctype;rec2 loc_dept%rowtype;rc3 rcpackage.rctype;rec3 outargs%rowtype;out_arg varchar2(255);

begin

-- Execute procedureout_arg := null;refcurproc@MSQL('Hello World', out_arg, rc1);

-- Fetch 20 rows from the remote emp table and insert them into loc_empfor 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 cursorclose rc1;

-- Get the next result set returned by the stored procedurerc2 := dbms_hs_result_set.get_next_result_set@MSQL;

-- Fetch 5 rows from the remote dept table and insert them into loc_deptfor i in 1 .. 5 loop

Database Compatibility Issues for SQL Server


fetch rc2 into rec2;insert into loc_dept values (rec2.deptno, rec2.dname, rec2.loc);

end loop;

--Close ref cursorclose 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 setrc3 := dbms_hs_result_set.get_next_result_set@MSQL;

-- Fetch them and insert them into the outargs tablefetch rc3 into rec3;insert into outargs (rec3.outarg, rec3.retval);

-- Close ref cursorclose rc3;

end;/

Database Compatibility Issues for SQL ServerSQL Server and Oracle databases function differently in some areas, causingcompatibility problems. The following compatibility issues are described in thissection:

■ Implicit Transactions (Chained Mode)

■ Column Definitions

■ Naming Rules

■ Data Types

■ Queries

■ Locking

Implicit Transactions (Chained Mode)The gateway supports the ANSI-standard implicit transactions. SQL Server storedprocedures must be written for this mode. Running implicit transactions allows thegateway to extend the Oracle two-phase commit protection to transactions updatingOracle and SQL Server databases.

Column DefinitionsBy default, a SQL Server table column cannot contain null values unless NULL isspecified in the column definition. SQL Server assumes all columns cannot containnull 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 inthe column definition.

Naming RulesNaming rule issues include the following:

■ Rules for Naming Objects



■ Case Sensitivity

Rules for Naming ObjectsOracle and SQL Server use different database object naming rules. For example, themaximum 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 ofalphanumeric characters can all be different.

Case SensitivityThe Oracle database defaults to uppercase unless you surround identifiers withdouble quote characters. For example, to refer to the SQL Server table called emp, enterthe 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 Oracleapplication, 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 uppercaseletters, you can enter the owner name without double quote characters, as follows:

SQL> SELECT * FROM SCOTT."emp"@MSQL;

Or

SQL> SELECT * FROM scott."emp"@MSQL;

Oracle recommends that you surround all SQL Server object names with double quotecharacters and use the exact letter case for the object names as they appear in the SQLServer data dictionary. This convention is not required when referring to thesupported Oracle data dictionary tables or views listed in Appendix C, "DataDictionary".

If existing applications cannot be changed according to these conventions, create viewsin Oracle to associate SQL Server names to the correct letter case. For example, to referto the SQL Server table emp from an existing Oracle application by using onlyuppercase 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 informationoriginating in the SQL Server data dictionary. You must be prepared to update theOracle view definitions whenever the data definitions for the corresponding tables arechanged in the SQL Server database.

Data TypesData type issues include the following:

See Also: Oracle Database Reference and SQL Serverdocumentation.



■ Binary Literal Notation

■ Bind Variables With LONG Columns

■ Data Type Conversion

Binary Literal NotationOracle SQL uses hexadecimal digits surrounded by single quotes to express literalvalues being compared or inserted into columns defined as data type RAW.

This notation is not converted to syntax compatible with the SQL Server VARBINARYand BINARY data types (a 0x followed by hexadecimal digits, surrounded by singlequotes).

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 bindvariables when inserting into or updating VARBINARY and BINARY data types.

Bind Variables With LONG ColumnsThe gateway does not support using bind variables to update columns of data typeLONG.

Data Type ConversionSQL Server does not support implicit date conversions. Such conversions must beexplicit.

For example, the gateway issues an error for the following SELECT statement:

SELECT DATE_COL FROM TEST@MSQLWHERE DATE_COL = "1-JAN-2004";

To avoid problems with implicit conversions, add explicit conversions, as in thefollowing:

SELECT DATE_COL FROM TEST@MSQLWHERE DATE_COL = TO_DATE("1-JAN-2004")

QueriesQuery issues include the following:

■ Row Selection

■ Empty Strings

■ Empty Bind Variables

Row SelectionSQL Server evaluates a query condition for all selected rows before returning any ofthe rows. If there is an error in the evaluation process for one or more rows, no rowsare returned even though the remaining rows satisfy the condition.

See Also: Appendix A, "Data Type Conversion" for moreinformation about restrictions on data types.

Known Restrictions


Oracle evaluates the query condition row-by-row and returns a row when theevaluation is successful. Rows are returned until a row fails the evaluation.

Empty StringsOracle processes an empty string in a SQL statement as a null value. SQL Serverprocesses an empty string as an empty string.

When comparing an empty string the gateway passes literal empty strings to the SQLServer database without any conversion. If you intended an empty string to representa null value, SQL Server does not process the statement that way; it uses the emptystring.

You can avoid this problem by using NULL or IS NULL in the SQL statement instead ofthe 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 asNULL value.

For CHAR columns, the gateway returns the full size of the column with each characteras empty space (’ ’).

Empty Bind VariablesFor VARCHAR bind variables, the gateway passes empty bind variables to the SQLServer database as a NULL value.

LockingThe locking model for an SQL Server database differs significantly from the Oraclemodel. The gateway depends on the underlying SQL Server behavior, so the followingpossible scenarios can affect Oracle applications that access SQL Server through thegateway:

■ Read access might block write access

■ Write access might block read access

■ Statement-level read consistency is not guaranteed

Known RestrictionsIf you encounter incompatibility problems not listed in this section or in "KnownProblems" on page 2-15, contact Oracle Support Services. The following sectiondescribes the known restrictions and includes suggestions for dealing with them whenpossible:

■ Multiple Open Statements

■ Transactional Integrity

■ Transaction Capability

■ COMMIT or ROLLBACK in PL/SQL Cursor Loops Closes Open Cursors

■ Stored Procedures

See Also: SQL Server documentation for information about theSQL Server locking model.

Known Restrictions


■ Pass-Through Feature

■ DDL Statements

■ SQL Syntax

■ Functions

■ SQL*Plus COPY Command with Lowercase Table Names

■ Database Links

■ CALLBACK links

Multiple Open StatementsAccessing SQL Server has the limitation that one open statement or cursor is allowedfor each connection. If a second statement or cursor needs to open in the sametransaction to access SQL Server, it requires a new connection.

Because of this limitation multiple open statements or cursors within the sametransaction 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.

Transactional IntegrityThe gateway cannot guarantee transactional integrity in the following cases:

■ When a statement that is processed by the gateway causes an implicit commit inthe target database

■ When the target database is configured to work in Autocommit Mode

The gateway sets Autocommit Mode to Off when a connection is established to theSQL Server database.

Transaction CapabilityThe gateway does not support savepoints. If a distributed update transaction is underway involving the gateway, and a user attempts to create a savepoint, the followingerror occurs:

ORA-02070: database dblink does not support savepoint in this context

By default, the gateway is configured as COMMIT_CONFIRM.

Note: If you have any questions or concerns about the restrictions,contact Oracle Support Services.

Note: Oracle strongly recommends the following:

■ If you know that executing a particular statement causes animplicit commit in the target database, then ensure that thisstatement is executed in its own transaction.

Known Restrictions


COMMIT or ROLLBACK in PL/SQL Cursor Loops Closes Open CursorsAny 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 ProceduresThe Oracle transaction manager or Oracle COMMIT or ROLLBACK commands cannotcontril changes issued through stored procedures that embed commits or rollbacks

When accessing stored procedures with result sets through the Oracle DatabaseGateway for SQL Server, you must work in the sequential mode of HeterogeneousServices.

When accessing stored procedures with multiple result sets through the OracleDatabase 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 FeatureIf the SQL statements being passed through the gateway result in an implicit commitat the SQL Server database, the Oracle transaction manager is unaware of the commitand an Oracle ROLLBACK command cannot be used to roll back the transaction.

DDL StatementsSQL 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 thestored procedure through the gateway using the procedural feature, or, if you executethe DDL statements through the gateway using the pass-through feature, an errorcondition might result. This is because the procedural feature and the pass-throughfeature of the gateway cannot guarantee that the DDL statements are executed in theirown separate transaction.

The following SQL Server DDL statements can cause an error condition if you attemptto pass them with the gateway pass-through feature, or if you execute a SQL Serverstored 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>

Known Restrictions


SQL SyntaxThis section lists restrictions on the following SQL syntax:

■ WHERE CURRENT OF Clause

■ CONNECT BY Clause

■ Functions in Subqueries

■ Parameters in Subqueries

■ Data Dictionary Table and Views in UPDATE Statement

■ ROWID

■ TO_DATE

■ EXPLAIN PLAN Statement

■ Callback Support

WHERE CURRENT OF ClauseUPDATE and DELETE statements with the WHERE CURRENT OF clause are not supported bythe gateway because they rely on the Oracle ROWID implementation. To update ordelete a specific row through the gateway, a condition style WHERE clause must be used.

CONNECT BY ClauseThe gateway does not support the CONNECT BY clause in a SELECT statement.

Functions in SubqueriesBind variables and expressions are not supported as operands in string functions ormathematical functions, when part of subquery in an INSERT, UPDATE, or DELETE SQLstatement.

DUMP TRANSACTION

GRANT

LOAD DATABASE

LOAD TRANSACTION

RECONFIGURE

REVOKE

SELECT INTO

TRUNCATE TABLE

UPDATE STATISTICS

See Also: SQL Server documentation for more information aboutDDL statements.

See Also: Appendix B, "Supported SQL Syntax and Functions"for more information about restrictions on SQL syntax.

Table 2–1 (Cont.) Restricted DDL Statements

Statement Name

Known Restrictions


Parameters in SubqueriesDue to a limitation in SQL Server, you cannot use parameters in subqueries.

Data Dictionary Table and Views in UPDATE StatementData dictionary tables and views in the SET clause of an UPDATE statement are notsupported.

ROWIDThe Oracle ROWID implementation is not supported.

TO_DATETO_DATE is a reserved word and cannot be used as a database identifier name.

EXPLAIN PLAN StatementThe EXPLAIN PLAN statement is not supported.

Callback SupportSQL statements that require the gateway to callback to Oracle database would not besupported.

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. Forexample:

INSERT INTO emp@non_oracle SELECT * FROM oracle_emp;

■ Any DELETE, INSERT, UPDATE or "SELECT... FOR UPDATE..." SQL statementcontaining SQL functions or statements that needs to be executed at theoriginating Oracle database.

These SQL functions include USER, USERENV, and SYSDATE, and the SQL statementsare in selects of data from the originating Oracle database. For example:

DELETE FROM emp@non_oracle WHERE hiredate > SYSDATE;

SELECT ename FROM tkhoemp@non_oracleWHERE hiredate IN (SELECT hiredate FROM tkhoemp)FOR UPDATE OF empno;

■ Any SQL statement that involves a table in Oracle database, and a LONG or LOBcolumn in a remote table. For example:

SELECT a.long1, b.empno FROM scott.table@non_oracle a, emp bWHERE a.id=b.empno;

SELECT a.long1, b.dummy FROM table_non@non_oracle a, dual b;

where a.long1 is a LONG column.

FunctionsThe following restrictions apply to using functions:

■ Unsupported functions cannot be used in statements that refer to LONG columns.

Known Problems


■ When negative numbers are used as the second parameter in a SUBSTR function,incorrect results are returned. This is due to incompatibility between the OracleSUBSTR function and the equivalent in SQL Server.

SQL*Plus COPY Command with Lowercase Table NamesYou 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 LinksThe gateway is not multithreaded and cannot support shared database links. Eachgateway session spawns a separate gateway process and connections cannot beshared.

CALLBACK linksOracle Database Gateway for SQL Server does not support CALLBACK links. Trying aCALLBACK link with the gateway will return the following error message:

ORA-02025: All tables in the SQL statement must be at the remote database

Known ProblemsThis section describes known problems and includes suggestions for correcting themwhen possible. If you have any questions or concerns about the problems, contactOracle Support Services. A current list of problems is available online. Contact yourlocal Oracle office for information about accessing the list.

The following known problems are described in this section:

■ Encrypted Format Login

■ Date Arithmetic

■ SQL Server IMAGE, TEXT and NTEXT Data Types

■ String Functions

■ Schema Names and PL/SQL

■ Data Dictionary Views and PL/SQL

■ Stored Procedures

Encrypted Format LoginThe Oracle9i database (Release 9.2 and earlier) supported an Oracle initializationparameter, DBLINK_ENCRYPT_LOGIN. When this parameter is set to TRUE, the passwordfor 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 Oracle9idatabase, you must change the setting to FALSE, the default setting, to allow Oracle9ito communicate with the gateway.

In the current release, Oracle Database 12c Release 1 (12.1), the DBLINK_ENCRYPT_LOGINinitialization parameter is obsolete, so you need not check it.

Known Problems


Date ArithmeticThe following SQL expressions do not function correctly with the gateway:

date + numbernumber + datedate - numberdate1 - date2

Statements with the preceding expressions are sent to the SQL Server database withoutany translation. Since SQL Server does not support these date arithmetic functions, thestatements return an error.

SQL Server IMAGE, TEXT and NTEXT Data TypesThe following restrictions apply when using IMAGE, TEXT, and NTEXT data types:

■ An unsupported SQL function cannot be used in a SQL statement that accesses acolumn 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 datatype 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 aSQL 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. Onestatement to access the IMAGE, TEXT or NTEXT column, and a second statement forthe other columns in the original statement.

The gateway does not support the PL/SQL function COLUMN_VALUE_LONG of the DBMS_SQL package.

String FunctionsIf you concatenate numeric literals using the "||" or CONCAT operator when using thegateway to query a SQL Server database, the result is an arithmetic addition. Forexample, 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/SQLIf you do not prefix a SQL Server database object with its schema name in a SQLstatement 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/SQLYou cannot refer to data dictionary views in SQL statements that are inside a PL/SQLblock.

See Also: Appendix B, "Supported SQL Syntax and Functions"for more information about restrictions on SQL syntax.

Known Problems


Stored ProceduresReturn values of stored procedures that return result sets are incorrect.

Known Problems


3

Case Studies 3-1

3 Case Studies

The following case studies for SQL Server demonstrate some of the features of theOracle Database Gateway. You can verify that the gateway is installed and operatingcorrectly by using the demonstration files included in the distribution media.

The demonstration files are automatically copied to disk when the gateway isinstalled.


■ Case Descriptions

■ Installation Media Contents

■ Demonstration Files

■ Demonstration Requirements

■ Creating Demonstration Tables

■ Case 1: Simple Queries

■ Case 2: A More Complex Query

■ Case 3: Joining SQL Server Tables

■ Case 4: Write Capabilities

■ Case 5: Data Dictionary Query

■ Case 6: The Pass-Through Feature

■ Case 7: Executing Stored Procedures

Case DescriptionsThe 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)

Installation Media Contents


Installation Media ContentsThe installation media contains the following:

■ Demonstration files

■ One SQL script file that creates the demonstration tables and stored procedures inthe SQL Server database

■ One SQL script file that drops the demonstration tables and stored proceduresfrom the SQL Server database

Demonstration FilesAfter a successful gateway installation, use the demonstration files stored in thedirectory ORACLE_HOME\dg4msql\demo where ORACLE_HOME is the directory under whichthe gateway is installed. The directory contains the following demonstration files:

Demonstration RequirementsThe case studies assume these requirements have been met:

■ The gateway demonstration tables and stored procedures are installed in the SQLServer 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 privateto the user SCOTT) which connects the gateway to a SQL Server database as SCOTTwith password TIGER2

For example, you can create the database link as follows:

SQL> CREATE DATABASE LINK GTWLINK CONNECT TO SCOTT2 IDENTIFIED BY TIGER2 USING 'GTWSID';

■ Oracle Net Services is configured correctly and running

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

Creating Demonstration Tables

Case Studies 3-3

Creating Demonstration TablesThe case studies are based on the GTW_EMP, GTW_DEPT, and GTW_SALGRADE tables and thestored procedures InsertDept and GetDept. If the demonstration tables and storedprocedures have not been created in the SQL Server database, use the bldmsql.sqlscript to create them. Enter the following:

> isql -USCOTT -PTIGER2 -ibldmsql.sql

The script creates the demonstration tables and stored procedures in the SQL Serverdatabase accordingly:

CREATE TABLE GTW_EMP (EMPNO SMALLINT NOT NULLENAME 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 InsertDeptgo

CREATE PROCEDURE InsertDept (@dno INTEGER,@dname VARCHAR(14), @loc VARCHAR(13))

AS INSERT INTO GTW_DEPT VALUES (@dno, @dname, @loc)go

DROP PROCEDURE GetDeptgo

CREATE PROCEDURE GetDept (@dno INTEGER, @dname VARCHAR(14) OUTPUT)AS SELECT @dname=DNAME FROM GTW_DEPT WHERE DEPTNO=@dnogo

Demonstration Table DefinitionsThe following table definitions use information retrieved by the SQL*PLUS DESCRIBEcommand:

GTW_EMP

Name Null? Type------------------------------- -------- ----EMPNO NOT NULL NUMBER(5)ENAME VARCHAR2(10)

Creating Demonstration Tables


JOB VARCHAR2(9)MGR NUMBER(5)HIREDATE DATESAL 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 ContentsThe 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 207499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 307521 WARD SALESMAN 7698 22-FEB-81 1250 500 307566 JONES MANAGER 7839 02-APR-81 2975 207654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 307698 BLAKE MANAGER 7839 01-MAY-81 2850 307782 CLARK MANAGER 7839 09-JUN-81 2450 107788 SCOTT ANALYST 7566 09-DEC-82 3000 207839 KING PRESIDENT 17-NOV-81 5000 107844 TURNER SALESMAN 7698 08-SEP-81 1500 0 307876 ADAMS CLERK 7788 12-JAN-83 1100 207900 JAMES CLERK 7698 03-DEC-81 950 307902 FORD ANALYST 7566 03-DEC-81 3000 207934 MILLER CLERK 7782 23-JAN-82 1300 10

GTW_DEPT

DEPTNO DNAME LOC----- -------------- --------

10 ACCOUNTING NEW YORK20 RESEARCH DALLAS30 SALES CHICAGO40 OPERATIONS BOSTON

GTW_SALGRADE

GRADE LOSAL HISAL------ ------ -----

1 700 12002 1201 14003 1401 2000

Case 4: Write Capabilities

Case Studies 3-5

4 2001 30005 3001 9999

Case 1: Simple QueriesCase 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 isworking correctly. The second query retrieves all the data from GTW_EMP including thetime portion of the hire date because the default date format was set to DD-MON-YYHH24:MM:SS for the session by an ALTER SESSION command.

Case 2: A More Complex QueryCase 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 arehigher than $10,000.

Case 3: Joining SQL Server TablesCase 3 demonstrates the following:

■ Joins between SQL Server tables

■ Subselects

The query retrieves information from three SQL Server tables and relates theemployees to their department name and salary grade, but only for those employeesearning more than the average salary.

Case 4: Write CapabilitiesCase 4 is split into three cases and demonstrates the following:

■ DELETE Statement

■ UPDATE Statement

■ INSERT Statement

DELETE StatementCase 4a demonstrates bind values and subselect. All employees in department 20 andone employee, WARD, in department 30 are deleted.

UPDATE StatementCase 4b provides an example of a simple UPDATE statement. In this example,employees are given a $100 a month salary increase.

Case 5: Data Dictionary Query


INSERT StatementCase 4c is an example of a simple insert statement that does not provide informationfor all columns.

Case 5: Data Dictionary QueryCase 5 demonstrates data dictionary mapping. It retrieves all the tables and views thatexist in the SQL Server database that begin with GTW.

Case 6: The Pass-Through FeatureCase 6 demonstrates the gateway pass-through feature which allows an application tosend commands or statements to SQL Server.

This case demonstrates:

■ A pass-through UPDATE statement using bind variables

■ A pass-through SELECT statement

UPDATE StatementCase 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 StatementCase 6b provides an example of a pass-through SELECT statement. The data that isreturned from the SELECT statement is inserted into a local table at the Oracle database.

Case 7: Executing Stored ProceduresCase 7 demonstrates the gateway executing a stored procedure in the SQL Serverdatabase.

A

Data Type Conversion A-1

A Data Type Conversion

This appendix contains the following section:

■ Data Type Conversion

Data Type ConversionThe gateway converts SQL Server data types to Oracle data types as follows:

Table A–1 Data Type Mapping and Restrictions

SQL Server Oracle CommentIf Oracle uses large varchar(32k)

BIGINT NUMBER(20)

BIGINT IDENTITY NUMBER(20)

BINARY RAW -

BIT NUMBER(3) -

CHAR CHAR -

DATETIME DATE Fractional parts of a second aretruncated

DECIMAL NUMBER(p[,s]) -

DECIMAL IDENTITY NUMBER(p[,s])

FLOAT FLOAT(53) -

IMAGE LONG RAW -

INT NUMBER(10)

INT IDENTITY NUMBER(10)

MONEY NUMBER(19,4) -

NCHAR NCHAR if the size is 1000 or less. If thesize is more than 1000, then it willbe mapped to LONG OracleDatabase Character Set =Unicode, otherwise, it is notsupported.

NTEXT LONG if Oracle DB Character Set =Unicode. Otherwise, it is notsupported

NVARCHAR NVARCHAR -

Data Type Conversion

A-2 Oracle Database Gateway for SQL Server User's Guide

NVARCHAR(MAX) LONG 4000 < N

if Oracle DB Character Set =Unicode. Otherwise, it is notsupported.

32767 < N

NUMERIC NUMBER(p[,s]) -

NUMERIC IDENTITY NUMBER(p[,s])

REAL FLOAT(24) -

SMALLDATETIME DATE -

SMALLMONEY NUMBER(10,4) -

SMALLINT NUMBER(5) -

SMALLINT IDENTITY NUMBER(5)

SYSNAME NVARCHAR -

TEXT LONG

TIMESTAMP RAW -

TINYINT NUMBER(3) -

TINYINT IDENTITY NUMBER(3)

VARBINARY RAW 1 < = N < = 2000 1 <= N <= 32767

VARBINARY(MAX) LONG RAW 2000 < N N < 32767

VARCHAR VARCHAR2 N < = 4000 N <= 32767

VARCHAR(MAX) LONG 4000 < N 32767 < N

XML LONG if Oracle Database Character Set =Unicode. Otherwise, it is notsupported.

Table A–1 (Cont.) Data Type Mapping and Restrictions

SQL Server Oracle CommentIf Oracle uses large varchar(32k)

B

Supported SQL Syntax and Functions B-1

B Supported SQL Syntax and Functions

This appendix contains the following sections:

■ Supported SQL Statements

■ Oracle Functions

Supported SQL StatementsWith 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. Noform 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 DDLstatements against the SQL Server database.

DELETEThe DELETE statement is fully supported. However, only Oracle functions supportedby SQL Server can be used.

INSERTThe INSERT statement is fully supported. However, only Oracle functions supportedby SQL Server can be used.

SELECTThe SELECT statement is fully supported, with these exceptions:

Note: TRUNCATE cannot be used in a pass-through statement.

See Also: Oracle Database Reference for detailed descriptions ofkeywords, parameters, and options.

See Also: "Functions Supported by SQL Server" on page B-2 for alist of supported functions.


Oracle Functions

B-2 Oracle Database Gateway for SQL Server User's Guide

■ CONNECT BY condition

■ NOWAIT

■ START WITH condition

■ WHERE CURRENT OF

UPDATEThe UPDATE statement is fully supported. However, only Oracle functions supportedby SQL Server can be used.

Oracle FunctionsAll functions are evaluated by the SQL Server database after the gateway hasconverted them to SQL Server SQL equivalents. The exception is the TO_DATE function,which is evaluated by the gateway.

Functions Not Supported by SQL ServerOracle SQL functions with no equivalent function in SQL Server are not supported inDELETE, INSERT, or UPDATE statements, but are evaluated by the Oracle database if thestatement is a SELECT statement. That is, the Oracle database performs post-processingof SELECT statements sent to the gateway.

If an unsupported function is used in a DELETE, INSERT, or UPDATE, statement, thefollowing Oracle error occurs:

ORA-02070: database db_link_name does not support function in this context

Functions Supported by SQL ServerThe gateway translates the following Oracle database functions in SQL statements totheir equivalent SQL Server functions:

■ Arithmetic Operators

■ Comparison Operators

■ Pattern Matching

■ Group Functions

■ String Functions

■ Other Functions

Arithmetic Operators


Oracle SQL Server

+ +

- -

* *

/ /

Oracle Functions

Supported SQL Syntax and Functions B-3

Comparison Operators

Pattern Matching

Group Functions

String Functions

Oracle SQL Server

= =

> >

< <

>= >=

<= <=

<>, !=, ^= <>

IS NOT NULL IS NOT NULL

IS NULL IS NULL

Oracle SQL Server

LIKE LIKE

NOT LIKE NOT LIKE

Oracle SQL Server

AVG AVG

COUNT COUNT

MAX MAX

MIN MIN

SUM SUM

Oracle SQL Server

||, CONCAT + (expression1 + expression2)

ASCII ASCII

CHR CHAR

INSTR (with two arguments) CHARINDEX

LENGTH () LEN ()

LENGTHB () DATALENGTH ()

LENGTHC () LEN ()

LOWER LOWER

LTRIM LTRIM

RTRIM RTRIM

Oracle Functions

B-4 Oracle Database Gateway for SQL Server User's Guide

Other Functions

Functions Supported by the GatewayIf an Oracle function has no equivalent function in SQL Server, the Oracle function isnot translated into the SQL statement and must be post-processed if the SQL statementis a SELECT.

The gateway, however, does support the TO_DATE function equivalent in SQL Server, asfollows:

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

date_column is a column with a date data type. It is converted to a parameter with atimestamp data type.

SUBSTR (second argument cannot be anegative number)

SUBSTRING

UPPER UPPER

Oracle SQL Server

ABS ABS

CEIL CEILING

COS COS

EXP EXP

FLOOR FLOOR

LN LOG

LOG LOG10

MOD %

NOT NVL IS NOT NULL

NVL IS NULL

POWER POWER

ROUND ROUND

SIN SIN

SQRT SQRT

TAN TAN

Recommendation: Supply the date string with the same format asthe result (that is, yyyyy-mm-dd hh:mi:ss.fff).

Oracle SQL Server

C

Data Dictionary C-1

C Data Dictionary

The Oracle Database Gateway for SQL Server translates a query that refers to anOracle database data dictionary table into a query that retrieves the data from SQLServer system tables. You perform queries on data dictionary tables over the databaselink in the same way you query data dictionary tables in the Oracle database. Thegateway data dictionary is similar to the Oracle database data dictionary inappearance and use.

This appendix contains the following sections:

■ Data Dictionary Support

■ Data Dictionary Mapping

■ Gateway Data Dictionary Descriptions

Data Dictionary SupportThe following paragraphs describe the Oracle Database Gateway for SQL Server datadictionary support.

SQL Server System TablesSQL Server data dictionary information is stored in the SQL Server database as SQLServer 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 changedata definitions, SQL Server reads and modifies the SQL Server system tables to addinformation about the user tables.

Accessing the Gateway Data DictionaryAccessing a gateway data dictionary table or view is identical to accessing a datadictionary in an Oracle database. You issue a SQL SELECT statement specifying adatabase link. The Oracle database data dictionary view and column names are usedto access the gateway data dictionary in an Oracle database. Synonyms of supportedviews are also acceptable. For example, the following statement queries the datadictionary 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 systemtable names. The gateway translates all data dictionary column names to theircorresponding SQL Server column names within the query. If the mappinginvolves one SQL Server system table, the gateway translates the requested table

Data Dictionary Support

C-2 Oracle Database Gateway for SQL Server User's Guide

name to its corresponding SQL Server system table name within the query. If themapping involves multiple SQL Server system tables, the gateway constructs ajoin in the query using the translated SQL Server system table names.

2. Sends the translated query to SQL Server.

3. Might convert the retrieved SQL Server data to give it the appearance of theOracle database data dictionary table.

4. Passes the data dictionary information from the translated SQL Server systemtable to the Oracle database.

Direct Queries to SQL Server TablesQueries issued directly to individual SQL Server system tables are allowed but theyreturn different results because the SQL Server system table column names differ fromthose of the data dictionary view. Also, certain columns in an SQL Server system tablecannot be used in data dictionary processing.

Supported Views and TablesThe gateway supports the following views and tables:

Note: The values returned when querying the gateway datadictionary might not be the same as the ones returned by the OracleSQL*Plus DESCRIBE command.

Supported Views and Table Supported Views and Table

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 ALL_VIEWS

DBA_CATALOG DBA_COL_COMMENTS

DBA_OBJECTS DBA_TAB_COLUMNS

DBA_TAB_COMMENTS DBA_TABLES

DICT_COLUMNS DICTIONARY

DUAL TABLE_PRIVILEGES

USER_CATALOG USER_COL_COMMENTS

USER_CONS_COLUMNS USER_CONSTRAINTS

USER_IND_COLUMNS USER_INDEXES

USER_OBJECTS USER_TAB_COLUMNS

USER_TAB_COMMENTS USER_TABLES

USER_USERS USER_VIEWS

Data Dictionary Mapping

Data Dictionary C-3

No other Oracle database data dictionary tables or views are supported. If you use aview not on the list, you will receive the Oracle database error code for no more rowsavailable.

Queries through the gateway of any data dictionary table or view beginning withALL_ can return rows from the SQL Server database even when access privileges forthose SQL Server objects have not been granted. When querying an Oracle databasewith the Oracle data dictionary, rows are returned only for those objects you arepermitted to access.

Data Dictionary MappingThe tables in this section list Oracle data dictionary view names and the equivalentSQL Server system tables used. A plus sign (+) indicates that a join operation isinvolved.

Table C–1 Oracle Data Dictionary View Names and SQL Server Equivalents

View Name SQL Server System Table Name

ALL_CATALOG sysusers + sysobjects

ALL_COL_COMMENTS sysusers + sysobjects + syscolumns

ALL_CONS_COLUMNS sp_pkeys + sp_fkeys

ALL_CONSTRAINTS sysusers + sysobjects + sysindexes +sysconstraints + sysreferences

ALL_IND_COLUMNS sysusers + sysindexes + syscolumns

ALL_INDEXES sysusers + sysindexes + sysobjects

ALL_OBJECTS sysusers + sysobjects + sysindexes

ALL_TAB_COLUMNS sysusers + sysobjects + syscolumns

ALL_TAB_COMMENTS sysusers + sysobjects

ALL_TABLES sysusers + sysobjects

ALL_USERS sysusers

ALL_VIEWS sysusers + sysobjects + syscomments

DBA_CATALOG sysusers + sysobjects

DBA_COL_COMMENTS sysusers + sysobjects + syscolumns

DBA_OBJECTS sysusers + sysobjects + sysindexes

DBA_TABLES sysusers + sysobjects

DBA_TAB_COLUMNS sysusers + sysobjects + syscolumns

DBA_TAB_COMMENTS sysusers + sysobjects

DICT_COLUMNS sysobjects + syscolumns

DICTIONARY sysobjects

DUAL sysusers

TABLE_PRIVILEGES sysprotects + sysusers + sysobjects

USER_CATALOG sysusers + sysobjects

USER_COL_COMMENTS sysusers + sysobjects + syscolumns

USER_CONS_COLUMNS sp_pkeys + sp_fkeys

Gateway Data Dictionary Descriptions


Default Column ValuesThere is a minor difference between the gateway data dictionary and a typical Oracledatabase data dictionary. The Oracle database columns that are missing in an SQLServer 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 DescriptionsThe 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 DESCRIBEcommand. The values in the Null? column might differ from the Oracle database datadictionary tables and views. Any default value is shown to the right of an item, butthis is not information returned by DESCRIBE.

USER_CONSTRAINTS sysusers + sysobjects + sysindexes +sysconstraints + sysreferences

USER_IND_COLUMNS sysusers + sysindexes + syscolumns

USER_INDEXES sysusers + sysindexes + sysobjects

USER_OBJECTS sysusers + sysobjects + sysindexes

USER_TAB_COLUMNS sysusers + sysobjects + syscolumns

USER_TAB_COMMENTS sysusers + sysobjects

USER_TABLES sysusers + sysobjects

USER_USERS sysusers

USER_VIEWS sysusers + sysobjects + syscomments

Note: The column width of some columns in the translated datadictionary tables would be different when the gateway connects toa SQL Server Version 7.0 database.

Table C–2 ALL_CATALOG

Name Type Value

OWNER VARCHAR2(256) -

TABLE_NAME VARCHAR2(256) -

TABLE_TYPE VARCHAR2(5) "TABLE" or"VIEW"

Table C–1 (Cont.) Oracle Data Dictionary View Names and SQL Server Equivalents

View Name SQL Server System Table Name


Data Dictionary C-5

Table C–3 ALL_COL_COMMENTS

Name Type Value



COLUMN_NAME VARCHAR2(256) -

COMMENTS VARCHAR2(1) -

Table C–4 ALL_CONS_COLUMNS

Name Type Value


CONSTRAINT_NAME VARCHAR2(256) -



POSITION NUMBER(5) -

Table C–5 ALL_CONSTRAINTS

Name Type Value



CONSTRAINT_TYPE VARCHAR2(1) "C" or "P" or "R"or "U"


SEARCH_CONDITION VARCHAR2(1) NULL

R_OWNER VARCHAR2(256) -

R_CONSTRAINT_NAME VARCHAR2(256) -

DELETE_RULE VARCHAR2(1) NULL

STATUS VARCHAR2(1) NULL

DEFERRABLE VARCHAR2(1) NULL

DEFERRED VARCHAR2(1) NULL

VALIDATED VARCHAR2(1) NULL

GENERATED VARCHAR2(1) NULL

BAD VARCHAR2(1) NULL

RELY VARCHAR2(1) NULL

LAST_CHANGE DATE -



Table C–6 ALL_IND_COLUMNS

Name Type Value

INDEX_OWNER VARCHAR2(256) -

INDEX_NAME VARCHAR2(256) -

TABLE_OWNER VARCHAR2(256) -



COLUMN_POSITION NUMBER(3) -

COLUMN_LENGTH NUMBER -

Char_LENGTH NUMBER -

DESCEND VARCHAR2(4) -

Table C–7 ALL_INDEXES

Name Type Value



INDEX_TYPE VARCHAR2(1) NULL



TABLE_TYPE VARCHAR(7) "TABLE" or"CLUSTER"

UNIQUENESS VARCHAR2(1) NULL

COMPRESSION VARCHAR2(1) NULL

PREFIX_LENGTH NUMBER 0

TABLESPACE_NAME VARCHAR2(1) NULL

INI_TRANS NUMBER 0

MAX_TRANS NUMBER 0

INITIAL_EXTENT NUMBER 0

NEXT_EXTENT NUMBER 0

MIN_EXTENTS NUMBER 0

MAX_EXTENTS NUMBER 0

PCT_INCREASE NUMBER 0

PCT_THRESHOLD NUMBER 0

INCLUDE_COLUMN NUMBER 0

FREELISTS NUMBER 0

FREELIST_GROUPS NUMBER 0

PCT_FREE NUMBER 0

LOGGING VARCHAR2(1) NULL


Data Dictionary C-7

BLEVEL NUMBER 0

LEAF_BLOCKS NUMBER 0

DISTINCT_KEYS NUMBER 0

AVG_LEAF_BLOCKS_PER_KEY NUMBER 0

AVG_DATA_BLOCKS_PER_KEY NUMBER 0

CLUSTERING_FACTOR NUMBER 0


NUM_ROWS NUMBER 0

SAMPLE_SIZE NUMBER 0

LAST_ANALYZED DATE NULL

DEGREE VARCHAR2(1) NULL

INSTANCES VARCHAR2(1) NULL

PARTITIONED VARCHAR2(1) NULL

TEMPORARY VARCHAR2(1) NULL


SECONDARY VARCHAR2(1) NULL

BUFFER_POOL VARCHAR2(1) NULL

USER_STATS VARCHAR2(1) NULL

DURATION VARCHAR2(1) NULL

PCT_DIRECT_ACCESS NUMBER 0

ITYP_OWNER VARCHAR2(1) NULL

ITYP_NAME VARCHAR2(1) NULL

PARAMETERS VARCHAR2(1) NULL

GLOBAL_STATS VARCHAR2(1) NULL

DOMIDX_STATUS VARCHAR2(1) NULL

DOMIDX_OPSTATUS VARCHAR2(1) NULL

FUNCIDX_STATUS VARCHAR2(1) NULL

Table C–8 ALL_OBJECTS

Name Type Value


OBJECT_NAME VARCHAR2(256) -

SUBOBJECT_NAME VARCHAR2(1) NULL

OBJECT_ID NUMBER -

DATA_OBJECT_ID NUMBER 0

Table C–7 (Cont.) ALL_INDEXES

Name Type Value



OBJECT_TYPE VARCHAR2(9) "TABLE" or "VIEW"or "INDEX" or"PROCEDURE"

CREATED DATE -

LAST_DDL_TIME DATE -

TIMESTAMP VARCHAR2(1) NULL

STATUS VARCHAR2(5) "VALID"




Table C–9 ALL_TAB_COLUMNS

Name Type Value




DATA_TYPE VARCHAR2(9) -

DATA_TYPE_MOD VARCHAR2(1) NULL

DATA_TYPE_OWNER VARCHAR2(1) NULL

DATA_LENGTH NUMBER -

DATA_PRECISION NUMBER -

DATA_SCALE NUMBER -

NULLABLE VARCHAR2(1) "Y" or "N"

COLUMN_ID NUMBER(5) -

DEFAULT_LENGTH NUMBER 0

DATA_DEFAULT VARCHAR2(1) NULL

NUM_DISTINCT NUMBER 0

LOW_VALUE NUMBER 0

HIGH_VALUE NUMBER 0

DENSITY NUMBER 0

NUM_NULLS NUMBER 0

NUM_BUCKETS NUMBER 0



CHARACTER_SET_NAME VARCHAR2(1) NULL

CHAR_COL_DEC_LENGTH NUMBER 0


Table C–8 (Cont.) ALL_OBJECTS

Name Type Value


Data Dictionary C-9


AVG_COL_LEN NUMBER 0

CHAR_LENGTH NUMBER

CHAR_USED VARCHAR2(1)

V80_FMT_IMAGE VARCHAR2(1)

DATA_UPGRADED VARCHAR2(1)

HISTOGRAM VARCHAR2(1)

Table C–10 ALL_TAB_COMMENTS

Name Type Value




COMMENTS VARCHAR2(1) NULL

Table C–11 ALL_TABLES

Name Type Value




CLUSTER_NAME VARCHAR2(1) NULL

IOT_NAME VARCHAR2(1) NULL

PCT_FREE NUMBER 0

PCT_USED NUMBER 0

INI_TRANS NUMBER 0

MAX_TRANS NUMBER 0






FREELISTS NUMBER 0



Table C–9 (Cont.) ALL_TAB_COLUMNS

Name Type Value



BACKED_UP VARCHAR2(1) NULL

NUM_ROWS NUMBER 0

BLOCKS NUMBER 0

EMPTY_BLOCKS NUMBER 0

AVG_SPACE NUMBER 0

CHAIN_CNT NUMBER 0

AVG_ROW_LEN NUMBER 0

AVG_SPACE_FREELIST_BLOCKS NUMBER 0

NUM_FREELIST_BLOCKS NUMBER 0



CACHE VARCHAR2(1) NULL

TABLE_LOCK VARCHAR2(1) NULL




IOT_TYPE VARCHAR2(1) NULL

TEMPORARY VARHCAR2(1) NULL


NESTED VARCHAR2(1) NULL


ROW_MOVEMENT VARCHAR2(1) NULL



DURATION VARHCAR2(1) NULL

SKIP_CORRUPT VARCHAR2(1) NULL

MONITORING VARCHAR2(1) NULL

Table C–12 ALL_USERS

Name Type Value

USERNAME VARCHAR2(256) -

USER_ID NUMBER(10) -

CREATED DATE -

Table C–11 (Cont.) ALL_TABLES

Name Type Value


Data Dictionary C-11

Table C–13 ALL_VIEWS

Name Type Value


VIEW_NAME VARCHAR2(256) -

TEXT_LENGTH NUMBER 0

TEXT VARCHAR2(1) -

TYPE_TEXT_LENGTH NUMBER 0

TYPE_TEXT VARCHAR2(1) -

OID_TEXT_LENGTH NUMBER 0

OID_TEXT VARCHAR2(1) -

VIEW_TYPE_OWNER VARCHAR2(1) -

VIEW_TYPE VARCHAR2(1) -

Table C–14 DBA_CATALOG

Name Type Value




Table C–15 DBA_COL_COMMENTS

Name Type Value





Table C–16 DBA_OBJECTS

Name Type Value




OBJECT_ID NUMBER -




OBJECT_TYPE VARCHAR2(9) "TABLE" or"VIEW" or"INDEX" or"PROCEDURE"

CREATED DATE -







Table C–17 DBA_TAB_COLUMNS

Name Type Value









DATA_SCALE NUMBER -






LOW_VALUE NUMBER 0

HIGH_VALUE NUMBER 0

DENSITY NUMBER 0

NUM_NULLS NUMBER 0





CHAR_COL_DEC_LENGTH NUMBER 0

Table C–16 (Cont.) DBA_OBJECTS

Name Type Value






Table C–18 DBA_TAB_COMMENTS

Name Type Value





Table C–19 DBA_TABLES

Name Type Value






PCT_FREE NUMBER 0

PCT_USED NUMBER 0

INI_TRANS NUMBER 0

MAX_TRANS NUMBER 0






FREELISTS NUMBER 0




NUM_ROWS NUMBER 0

BLOCKS NUMBER 0


Table C–17 (Cont.) DBA_TAB_COLUMNS

Name Type Value



AVG_SPACE NUMBER 0

CHAIN_CNT NUMBER 0






















Table C–20 DICT_COLUMNS

Name Type Value




Table C–21 DICTIONARY

Name Type Value


COMMENTS VARCHAR2(1) -

Table C–19 (Cont.) DBA_TABLES

Name Type Value



Table C–22 DUAL

Name Type Value

DUMMY VARCHAR2(1) "X"

Table C–23 TABLE_PRIVILEGES

Name Type Value

GRANTEE VARCHAR2(256) -



GRANTOR VARCHAR2(256) -

SELECT_PRIV VARCHAR2(1) "Y"

INSERT_PRIV VARCHAR2(1) "A"

DELETE_PRIV VARCHAR2(1) "Y"

UPDATE_PRIV VARCHAR2(1) "A"

REFERENCES_PRIV VARCHAR2(1) "A"

ALTER_PRIV VARCHAR2(1) "Y"

INDEX_PRIV VARCHAR2(1) "Y"

CREATED DATE -

Table C–24 USER_CATALOG

Name Type Value



Table C–25 USER_COL_COMMENTS

Name Type Value




Table C–26 USER_CONS_COLUMNS

Name Type Value







POSITION NUMBER(5) -

Table C–27 USER_CONSTRAINTS

Name Type Value



CONSTRAINT_TYPE VARCHAR2(1) "R" or "P" or "U"or "C"


SEARCH_CONDITION VARCHAR2(1) NULL

R_OWNER VARCHAR2(256) -

R_CONSTRAINT_NAME VARCHAR2(256) -

DELETE_RULE VARCHAR2(1) NULL


DEFERRABLE VARCHAR2(1) NULL

DEFERRED VARCHAR2(1) NULL

VALIDATED VARCHAR2(1) NULL


BAD VARCHAR2(1) NULL

RELY VARCHAR2(1) NULL

LAST_CHANGE DATE -

Table C–28 USER_IND_COLUMNS

Name Type Value




COLUMN_POSITION NUMBER(3) -

COLUMN_LENGTH NUMBER -

CHAR_LENGTH NUMBER -

DESCEND VARCHAR2(4) -

Table C–26 (Cont.) USER_CONS_COLUMNS

Name Type Value



Table C–29 USER_INDEXES

Name Type Value


INDEX_TYPE VARCHAR2(1) NULL



TABLE_TYPE VARCHAR2(7) "TABLE" or"CLUSTER"

UNIQUENESS VARCHAR2(1) NULL

COMPRESSION VARCHAR2(1) NULL

PREFIX_LENGTH NUMBER 0


INI_TRANS NUMBER 0

MAX_TRANS NUMBER 0






PCT_THRESHOLD NUMBER 0

INCLUDE_COLUMN NUMBER 0

FREELISTS NUMBER 0


PCT_FREE NUMBER 0


BLEVEL NUMBER 0

LEAF_BLOCKS NUMBER 0

DISTINCT_KEYS NUMBER 0

AVG_LEAF_BLOCKS_PER_KEY NUMBER 0

AVG_DATA_BLOCKS_PER_KEY NUMBER 0

CLUSTERING_FACTOR NUMBER 0


NUM_ROWS NUMBER 0














PCT_DIRECT_ACCESS NUMBER 0

ITYP_OWNER VARCHAR2(1) NULL

ITYP_NAME VARCHAR2(1) NULL

PARAMETERS VARCHAR2(1) NULL


DOMIDX_STATUS VARCHAR2(1) NULL

DOMIDX_OPSTATUS VARCHAR2(1) NULL

FUNCIDX_STATUS VARCHAR2(1) NULL

Table C–30 USER_OBJECTS

Name Type Value



OBJECT_ID NUMBER -


OBJECT_TYPE VARCHAR2(9) "TABLE" or"VIEW" or"INDEX" or"PROCEDURE"

CREATED DATE -



STATUS VARCHAR2(5) "VALID"




Table C–31 USER_TAB_COLUMNS

Name Type Value



Table C–29 (Cont.) USER_INDEXES

Name Type Value








DATA_SCALE NUMBER -






LOW_VALUE NUMBER 0

HIGH_VALUE NUMBER 0

DENSITY NUMBER 0

NUM_NULLS NUMBER 0





CHAR_COL_DECL_LENGTH NUMBER 0




CHAR_LENGTH NUMBER 0

CHAR_USED VARCHAR2(1)

V80_FMT_IMAGE VARCHAR2(1)

DATA_UPGRADED VARCHAR2(1)

HISTOGRAM VARCHAR2(1)

Table C–32 USER_TAB_COMMENTS

Name Type Value




Table C–31 (Cont.) USER_TAB_COLUMNS

Name Type Value



Table C–33 USER_TABLES

Name Type Value





PCT_FREE NUMBER 0

PCT_USED NUMBER 0

INI_TRANS NUMBER 0

MAX_TRANS NUMBER 0






FREELISTS NUMBER 0




NUM_ROWS NUMBER 0

BLOCKS NUMBER 0


AVG_SPACE NUMBER 0

CHAIN_CNT NUMBER 0





















DURATION VARCHAR2(1) NULL



Table C–34 USER_USERS

Name Type Value

USERNAME VARCHAR2(256) -

USER_ID NUMBER(5) -

ACCOUNT_STATUS VARCHAR2(4) "OPEN"

LOCK_DATE DATE NULL

EXPIRY_DATE DATE NULL

DEFAULT_TABLESPACE VARCHAR2(1) NULL

TEMPORARY_TABLESPACE VARCHAR2(1) NULL

CREATED DATE -

INITIAL_RSRC_CONSUMER_GROUP VARCHAR2(1) NULL

EXTERNAL_NAME VARCHAR2(1) NULL

Table C–35 USER_VIEWS

Name Type Value

VIEW_NAME VARCHAR2(256) -

TEXT_LENGTH NUMBER 0

TEXT VARCHAR2(1) -

TYPE_TEXT_LENGTH NUMBER 0

TYPE_TEXT VARCHAR2(1) NULL

OID_TEXT_LENGTH NUMBER 0

OID_TEXT VARCHAR2(1) NULL

VIEW_TYPE_OWNER VARCHAR2(1) NULL

VIEW_TYPE VARCHAR2(1) NULL

Table C–33 (Cont.) USER_TABLES

Name Type Value



D

Initialization Parameters D-1

D Initialization Parameters

The Oracle database initialization parameters in the init.ora file are distinct fromgateway initialization parameters. Set the gateway parameters in the initializationparameter file using an agent-specific mechanism, or set them in the Oracle datadictionary using the DBMS_HS package. The gateway initialization parameter file mustbe available when the gateway is started.

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

■ Initialization Parameter File Syntax

■ Oracle Database Gateway for SQL Server Initialization Parameters

■ Initialization Parameter Descriptions

Initialization Parameter File SyntaxThe syntax for the initialization parameter file is as follows:

1. The file is a sequence of commands.

2. Each command should start on a separate line.

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

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

5. Set the parameter values as follows:

[SET][PRIVATE] parameter=value

Where:

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

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

a. A string of characters that does not contain any backslashes, white space ordouble quotation marks (")

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

Oracle Database Gateway for SQL Server Initialization Parameters

D-2 Oracle Database Gateway for SQL Server User's Guide

* 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 abackslash precedes any other character then the backslash is ignored.

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

HS_FDS_TRACE_LEVEL=ON

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

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

PRIVATE specifies that the initialization parameter should be private to the agentand should not be uploaded to the Oracle database. Most initialization parametersshould not be private. If, however, you are storing sensitive information like apassword in the initialization parameter file, then you may not want it uploadedto the server because the initialization parameters and values are not encryptedwhen uploaded. Making the initialization parameters private prevents the uploadfrom happening and they do not appear in dynamic performance views. UsePRIVATE for the initialization parameters only if the parameter value includessensitive information such as a user name or password.

SET PRIVATE specifies that the parameter value is set as an environment variablefor 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 ParametersThis section lists all the initialization file parameters that can be set for the OracleDatabase Gateway for SQL Server. They are as follows:

■ HS_CALL_NAME

■ HS_DB_DOMAIN

■ HS_DB_INTERNAL_NAME

■ HS_DB_NAME

■ HS_DESCRIBE_CACHE_HWM

■ HS_LANGUAGE

■ HS_LONG_PIECE_TRANSFER_SIZE

■ HS_OPEN_CURSORS

■ HS_RPC_FETCH_REBLOCKING

Initialization Parameter Description


■ HS_RPC_FETCH_SIZE

■ HS_TIME_ZONE

■ HS_TRANSACTION_MODEL

■ IFILE

■ HS_FDS_TIMESTAMP_MAPPING

■ HS_FDS_DATE_MAPPING

■ HS_FDS_CONNECT_INFO

■ HS_FDS_PROC_IS_FUNC

■ HS_FDS_RECOVERY_ACCOUNT

■ HS_FDS_RECOVERY_PWD

■ HS_FDS_REPORT_REAL_AS_DOUBLE

■ HS_FDS_RESULTSET_SUPPORT

■ HS_FDS_TRACE_LEVEL

■ HS_FDS_TRANSACTION_LOG

■ HS_FDS_FETCH_ROWS

■ HS_IDLE_TIMEOUT

■ HS_NLS_LENGTH_SEMANTICS

■ HS_KEEP_REMOTE_COLUMN_SIZE

■ HS_FDS_REMOTE_DB_CHARSET

■ HS_FDS_SUPPORT_STATISTICS

■ HS_FDS_RSET_RETURN_ROWCOUNT

■ HS_FDS_SQLLEN_INTERPRETATION

■ HS_FDS_ARRAY_EXEC

Initialization Parameter DescriptionThe following sections describe all the initialization file parameters that can be set forgateways.

HS_CALL_NAME

Specifies the remote functions that can be referenced in SQL statements. The value is alist of remote functions and their owners, separated by semicolons, in the followingformat:

owner_name.function_name

For example:

Property Description

Default value None

Range of values Not applicable



owner1.A1;owner2.A2;owner3.A3

If an owner name is not specified for a remote function, the default owner namebecomes the user name used to connect to the remote database (specified when theHeterogeneous Services database link is created or taken from user session if notspecified in the DB link).

The entries for the owner names and the function names are case sensitive.

HS_DB_DOMAIN

Specifies a unique network sub-address for a non-Oracle system. The HS_DB_DOMAINinitialization parameter is similar to the DB_DOMAIN initialization parameter, describedin the Oracle Database Reference. The HS_DB_DOMAIN initialization parameter is requiredif you use the Oracle Names server. The HS_DB_NAME and HS_DB_DOMAIN initializationparameters define the global name of the non-Oracle system.

HS_DB_INTERNAL_NAME

Specifies a unique hexadecimal number identifying the instance to which theHeterogeneous Services agent is connected. This parameter's value is used as part of atransaction ID when global name services are activated. Specifying a nonuniquenumber can cause problems when two-phase commit recovery actions are necessaryfor a transaction.

HS_DB_NAME

Specifies a unique alphanumeric name for the data store given to the non-Oraclesystem. This name identifies the non-Oracle system within the cooperative serverenvironment. The HS_DB_NAME and HS_DB_DOMAIN initialization parameters define theglobal name of the non-Oracle system.


Default value WORLD

Range of values 1 to 199 characters

Note: The HS_DB_NAME and HS_DB_DOMAIN initialization parametersmust combine to form a unique address in a cooperative serverenvironment.


Default value 01010101

Range of values 1 to 16 hexadecimal characters


Default value HO

Range of values 1 to 8 characters



HS_DESCRIBE_CACHE_HWM

Specifies the maximum number of entries in the describe cache used byHeterogeneous Services. This limit is known as the describe cache high water mark.The cache contains descriptions of the mapped tables that Heterogeneous Servicesreuses 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 improveperformance. Increasing the high water mark improves performance at the cost ofmemory usage.

HS_LANGUAGE

Provides Heterogeneous Services with character set, language, and territoryinformation of the non-Oracle data source. The value must use the following format:

language[_territory.character_set]

Character SetsIdeally, the character sets of the Oracle database and the non-Oracle data source arethe same. In almost all cases, HS_LANGUAGE should be set exactly the same as Oracledatabase character set for optimal character set mapping and performance. If they arenot the same, Heterogeneous Services attempts to translate the character set of thenon-Oracle data source to the Oracle database character set, and back again. Thetranslation can degrade performance. In some cases, Heterogeneous Services cannottranslate a character from one character set to another.

As more Oracle databases and non-Oracle databases use Unicode as databasecharacter sets, it is preferable to also run the gateway in Unicode character set. To doso, you must set HS_LANGUAGE=AL32UTF8. However, when the gateway runs onWindows, the Microsoft ODBC Driver Manager interface can exchange data only inthe double-byte character set, UCS2. This results in extra ratio expansion of describedbuffer and column sizes. Refer to HS_FDS_REMOTE_DB_CHARSET for instruction on


Default value 100

Range of values 1 to 4000


Default value System-specific

Range of values Any valid language name (up to 255 characters)

Note: The globalization support initialization parameters affecterror messages, the data for the SQL Service, and parameters indistributed external procedures.

Note: The specified character set must be a superset of theoperating system character set on the platform where the agent isinstalled.



how to adjust to correct sizes.

LanguageThe 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 genericHeterogeneous Services messages (ORA-25000 through ORA-28000). These arecontrolled by the session settings in the Oracle database.

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

HS_LONG_PIECE_TRANSFER_SIZE

Sets the size of the piece of LONG data being transferred. A smaller piece size means lessmemory requirement, but more round-trips to fetch all the data. A larger piece sizemeans fewer round-trips, but more of a memory requirement to store the intermediatepieces internally. Thus, the initialization parameter can be used to tune a system forthe best performance, with the best trade-off between round-trips and memoryrequirements, and network latency or response time.

HS_OPEN_CURSORS

Defines the maximum number of cursors that can be open on one connection to anon-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 Oracledatabase is recommended.


Default value 64 KB

Range of values Any value up to 2 GB


Default value 50

Range of values 1 to the value of Oracle's OPEN_CURSORS initialization parameter



HS_RPC_FETCH_REBLOCKING

Controls whether Heterogeneous Services attempts to optimize performance of datatransfer between the Oracle database and the Heterogeneous Services agent connectedto the non-Oracle data store.

The following values are possible:

■ OFF disables reblocking of fetched data so that data is immediately sent from agentto server.

■ ON enables reblocking, which means that data fetched from the non-Oracle systemis buffered in the agent and is not sent to the Oracle database until the amount offetched data is equal to or higher than the value of HS_RPC_FETCH_SIZEinitialization parameter. However, any buffered data is returned immediatelywhen a fetch indicates that no more data exists or when the non-Oracle systemreports an error.

HS_RPC_FETCH_SIZE

Tunes internal data buffering to optimize the data transfer rate between the server andthe agent process.

Increasing the value can reduce the number of network round-trips needed to transfera given amount of data, but also tends to increase data bandwidth and to reducelatency as measured between issuing a query and completion of all fetches for thequery. Nevertheless, increasing the fetch size can increase latency for the initial fetchresults of a query, because the first fetch results are not transmitted until additionaldata is available.

HS_TIME_ZONE

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

HS_TIME_ZONE = [+ | -] hh:mm


Default value ON

Range of values OFF or ON


Default value 50000

Range of values 1 to 10000000


Default value for'[+|-]hh:mm'

Derived from the NLS_TERRITORY initialization parameter

Range of values for'[+|-]hh:mm'

Any valid datetime format mask



HS_TRANSACTION_MODEL

Specifies the type of transaction model that is used when the non-Oracle database isupdated by a transaction.

The following values are possible:

■ COMMIT_CONFIRM provides read and write access to the non-Oracle database andallows the gateway to be part of a distributed update. To use the commit-confirmmodel, the following items must be created in the non-Oracle database:

– Transaction log table. The default table name is HS_TRANSACTION_LOG. Adifferent name can be set using the HS_FDS_TRANSACTION_LOG parameter. Thetransaction log table must be granted SELECT, DELETE, and INSERT privilegesset 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.

■ READ_ONLY_AUTOCOMMIT provides read only access to the non-Oracle database thatdoes not use logging.

■ SINGLE_SITE_AUTOCOMMIT provides read and write access to the non-Oracledatabase without logging. The gateway cannot participate in distributed updates.Moreover, any update to the non-Oracle database is committed immediately.

IFILE

Use the IFILE initialization parameter to embed another initialization file within thecurrent initialization file. The value should be an absolute path and should not containenvironment variables. The three levels of nesting limit do not apply.


Default Value COMMIT_CONFIRM

Range of Values COMMIT_CONFIRM, READ_ONLY, SINGLE_SITE, READ_ONLY_AUTOCOMMIT, SINGLE_SITE_AUTOCOMMIT


Default value None

Range of values Valid parameter file names

See Also: Oracle Database Reference



HS_FDS_TIMESTAMP_MAPPING

If set to CHAR (default), non-Oracle target timestamp would be mapped to CHAR(26).IIf set to DATE, then non-Oracle target timestamp would be mapped to Oracle date. Ifset to TIMESTAMP, non-Oracle traget timestamp would be mapped to Oracletimestamp.

HS_FDS_DATE_MAPPING

If set to CHAR, then non-oracle target date would be mapped to CHAR(10). If set to DATE,then non-Oracle target date would be mapped to Oracle date.

HS_FDS_CONNECT_INFO

HS_FDS_CONNECT_INFO that describes the connection to the non-Oracle system.

The default initialization parameter file already has an entry for this parameter. Thesyntax 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 SQLServer database, port_number is the port number of the SQL Server, instance_name isthe instance of SQL Server running on the machine, and database_name is the SQLServer database name.

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

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


Default Value DATE

Range of Values CHAR|DATE|TIMESTAMP

Syntax HS_FDS_TIMESTAMP_MAPPING={CHAR|DATE|TIMESTAMP}


Default Value DATE

Range of Values DATE|CHAR

Syntax HS_FDS_DATE_MAPPING={DATE|CHAR}


Default Value None

Range of Values Not applicable



HS_FDS_CONNECT_INFO=host_name/instance_nameHS_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 SQLServer 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 anddatabase_name is provided, the slash (/) is required. This can be shown as follows:

HS_FDS_CONNECT_INFO= host_name//database_name

This release supports IPv6 format, so you can enter IPv6 format in place of hostname,but you need to wrap square brackets around the IPv6 specification.

For example,

HS_FDS_CONNECT_INFO=[2001:0db8:20c:f1ff:fec6:38af]:port_number/…

HS_FDS_PROC_IS_FUNC

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

HS_FDS_RECOVERY_ACCOUNT

Specifies the name of the recovery account used for the commit-confirm transactionmodel. An account with user name and password must be set up at the non-Oraclesystem. For more information about the commit-confirm model, see the HS_TRANSACTION_MODEL parameter.

The name of the recovery account is case sensitive.


Default Value FALSE

Range of Values TRUE, FALSE

Note: If you set this initialization parameter, you must change thesyntax of the procedure execute statement for all existing storedprocedures to handle return values.


Default Value RECOVER

Range of values Any valid user ID



HS_FDS_RECOVERY_PWD

Specifies the password of the recovery account used for the commit-confirmtransaction model set up at the non-Oracle system. For more information about thecommit-confirm model, see the HS_TRANSACTION_MODEL parameter.

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

HS_FDS_REPORT_REAL_AS_DOUBLE

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

HS_FDS_RESULTSET_SUPPORT

Enables result sets to be returned from stored procedures. By default, all storedprocedures do not return a result set to the user.

HS_FDS_TRACE_LEVEL

Specifies whether error tracing is turned on or off for gateway connectivity.

The following values are valid:


Default Value RECOVER

Range of values Any valid password


Default Value FALSE



Default Value FALSE


Note: If you set this initialization parameter, you must do thefollowing:

■ Change the syntax of the procedure execute statement for allexisting stored procedures, to handle result sets

■ Work in the sequential mode of Heterogeneous Services


Default Value OFF

Range of values OFF, ON, DEBUG



■ OFF disables the tracing of error messages.

■ ON enables the tracing of error messages that occur when you encounterproblems. The results are written by default to a gateway log file in LOG directorywhere the gateway is installed.

■ DEBUG enables the tracing of detailed error messages that can be used fordebugging.

HS_FDS_TRANSACTION_LOG

Specifies the name of the table created in the non-Oracle system for loggingtransactions. For more information about the transaction model, see the HS_TRANSACTION_MODEL parameter.

HS_FDS_FETCH_ROWS

HS_FDS_FETCH_ROWS specifies the fetch array size. This is the number of rows to befetched 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.

HS_IDLE_TIMEOUT

This feature is only available for Oracle Net TCP protocol. When there is no activity fora connected gateway session for this specified time period, the gateway session wouldbe terminated automatically with pending update (if any) rolled back.

HS_NLS_LENGTH_SEMANTICS


Default Value HS_TRANSACTION_LOG

Range of Values Any valid table name


Default Value 100

Range of Values Any integer between 1 and 1000

Syntax HS_FDS_FETCH_ROWS=num


Default Value 0 (no timeout)

Range of Values 0-9999 (minutes)

Syntax HS_IDLE_TIMEOUT=num


Default Value BYTE



This release of gateway has Character Semantics functionality equivalent to the OracleDatabase Character Semantics, that is, NLS_LENGTH_SEMANTICS. When HS_NLS_LENGTH_SEMANTICS is set to CHAR, the (VAR)CHAR columns of SQL Server database are to beinterpreted as having CHAR semantics. The only situation the gateway does not honorthe HS_NLS_LENGTH_SEMANTICS=CHAR setting is when both Oracle database and thegateway are on the same multi-byte character set

HS_KEEP_REMOTE_COLUMN_SIZE

HS_KEEP_REMOTE_COLUMN_SIZE specifies whether to suppress ratio expansion whencomputing the length of (VAR)CHAR datatypes during data conversion from thenon-Oracle database to the gateway, and then to the Oracle database. When it is set toREMOTE, the expansion is suppressed between the non-Oracle database and thegateway. When it is set to LOCAL, the expansion is suppressed between the gatewayand the Oracle database. When it is set to ALL, the expansion is suppressed from thenon-Oracle database to the Oracle database.

When the parameter is set, the expansion is suppressed when reporting the remotecolumn size, calculating the implicit resulting buffer size, and instantiating in the localOracle database. This has effect only for remote column size from non-Oracle databaseto Oracle database. If the gateway runs on Windows and HS_LANGUAGE=AL32UTF8, thenyou must not specify this parameter, as it would influence other ratio relatedparameter operation. It has no effect for calculating ratio for data moving from Oracledatabase to non-Oracle database through gateway during INSERT, UPDATE, or DELETE.

HS_FDS_REMOTE_DB_CHARSET

This parameter is valid only when HS_LANGUAGE is set to AL32UTF8 and the gatewayruns on Windows. As more Oracle databases and non-Oracle databases use Unicode asdatabase character sets, it is preferable to also run the gateway in Unicode characterset. To do so, you must set HS_LANGUAGE=AL32UTF8. However, when the gateway runson Windows, the Microsoft ODBC Driver Manager interface can exchange data only in

Range of Values BYTE | CHAR

Syntax HS_NLS_LENGTH_SEMANTICS = { BYTE | CHAR }


Default Value OFF

Range of Values OFF | LOCAL | REMOTE | ALL

Syntax HS_KEEP_REMOTE_COLUMN_SIZE = OFF | LOCAL | REMOTE| ALL

Parameter type String


Default Value None

Range of values Not applicable

Syntax HS_FDS_REMOTE_DB_CHARSET




the double-byte character set, UCS2. This results in extra ratio expansion of describedbuffer and column sizes. To compensate, the gateway can re-adjust the column size ifHS_FDS_REMOTE_DB_CHARSET is set to the corresponding non-Oracle database characterset. For example, HS_FDS_REMOTE_DB_CHARSET=KO16KSC5601.

HS_FDS_SUPPORT_STATISTICS

We gather statistics from the non-Oracle database by default. You can choose to disablethe gathering of remote database statistics by setting the HS_FDS_SUPPORT_STATISTICSparameter to FALSE.

HS_FDS_RSET_RETURN_ROWCOUNT

When set to TRUE, the gateway returns the row counts of DML statements that areexecuted inside a stored procedure. The row count is returned as a single row, singlecolumn result set of type signed integer.

When set to FALSE, the gateway skips the row counts of DML statements that areexecuted inside a stored procedure. This is the default behavior, and it is the behaviorof 11.1 and older gateways.

HS_FDS_SQLLEN_INTERPRETATION

This parameter is only valid for 64 bit platforms. ODBC standard specifies SQLLEN (ofinternal ODBC construct) being 64 bit on 64 bit platforms, but some ODBC drivermanagers and drivers violate this convention, and implement it as 32 bit. In order forthe gateway to compensate their behavior, you need to specify HS_FDS_SQLLEN_INTERPRETATION=32 if you use these types of driver managers and driver.


Default Value TRUE

Range of values {TRUE|FALSE}

Syntax HS_FDS_SUPPORT_STATISTICS= {TRUE|FALSE}


Default Value FALSE


Syntax HS_FDS_RSET_RETURN_ROWCOUNT= {TRUE|FALSE}


Default Value 64

Range of values {64|32}

Syntax HS_FDS_SQLLEN_INTERPRETATION= {64|32}



HS_FDS_ARRAY_EXEC

If set to TRUE, the gateway will use array operations for insert, update, deletestatements containing binds against the remote data source. The array size isdetermined by the value of the HS_FDS_FETCH_ROWS init parameter.

If set to FALSE, the gateway will not use array operations for insert, update, and deletestatements. Instead, a single statement will be issued for every value.


Default Value TRUE


Syntax HS_FDS_ARRAY_EXEC= {TRUE|FALSE}



Index-1

Index

AALTER statement, B-1Arithmetic operators, B-2

BBIGINT data type, A-1BINARY data type, A-1BIT data type, A-1

CCase rules, 2-8Case studies, 3-1Chained mode, 2-7CHAR data type, A-1character sets

Heterogeneous Services, D-5COMMIT

restrictions, 2-12Comparison operators, B-3CONCAT operator, 2-16CONNECT BY clause, 2-13COPY command, 2-15CREATE statement, B-1Cursor loops

restrictions, 2-12

DData definition language, B-1Data dictionary

views, C-2Data type

BIGINT, A-1BINARY, A-1BIT, A-1CHAR, A-1conversion, 2-9DATE, A-1DATETIME, A-1DECIMAL, A-1FLOAT, A-1IMAGE, A-1LONG RAW, A-1MONEY, A-1

NCHAR, A-1NUMBER, A-1NUMERIC, A-2NVARCHAR, A-1RAW, A-1REAL, A-2SMALL DATETIME, A-2SMALL MONEY, A-2SMALLINT, A-2TIMESTAMP, A-2TINYINT, A-2VARBINARY, 2-15, A-2VARCHAR, A-2

DATE data type, A-1DATETIME data type, A-1DECIMAL data type, A-1DELETE statement, 3-5, B-1, B-2demonstration build SQL script, 3-2Demonstration files, 3-2Demonstration tables, 3-3Demonstration tables build SQL script, 3-3describe cache high water mark

definition, D-5DROP statement, B-1

EEncrypted format login, 2-15Error messages

error tracing, D-11Errors

ORA-02070, 2-11Executing Stored Procedures, 3-6

Ffetch array size, with HS_FDS_FETCH_ROWS, D-12FLOAT data type, A-1Functions in SQL, 2-2

GGateway

case studies, 3-1data dictionary tables, C-1pass-through feature, 2-1, 2-12

Index-2

supported functions, B-1supported SQL syntax, B-1

globalization supportHeterogeneous Services, D-5

GRANT statement, B-1Group functions, B-3

HHeterogeneous Services

defining maximum number of open cursors, D-6optimizing data transfer, D-7setting global name, D-4specifying cache high water mark, D-5tuning internal data buffering, D-7tuning LONG data transfer, D-6

Hexadecimal notation, 2-9HS_CALL_NAME initialization parameter, D-3HS_DB_NAME initialization parameter, D-4HS_DESCRIBE_CACHE_HWM initialization

parameter, D-5HS_FDS_CONNECT_INFO, D-9HS_FDS_FETCH_ROWS parameter, D-12HS_FDS_PROC_IS_FUNC initialization

parameter, D-10HS_FDS_RECOVERY_PWD initialization

parameter, D-11HS_FDS_RESULTSET_SUPPORT initialization

parameter, D-11HS_FDS_TRACE_LEVEL initialization

parameter, D-11enabling agent tracing, D-2

HS_FDS_TRANSACTION_LOG initializationparameter, D-12

HS_IDLE_TIMEOUT initialization parameter, D-12HS_KEEP_REMOTE_COLUMN_SIZE initialization

parameter, D-13HS_LANGUAGE initialization parameter, D-5HS_LONG_PIECE_TRANSFER_SIZE initialization

parameter, D-6HS_NLS_LENGTH_SEMANTICS initialization

parameter, D-13HS_OPEN_CURSORS initialization parameter, D-6HS_RPC_FETCH_REBLOCKING initialization

parameter, D-7HS_RPC_FETCH_SIZE initialization parameter, D-7HS_TIME_ZONE initialization parameter, D-7

IIFILE initialization parameter, D-8IMAGE data type, A-1Initialization parameter file

customizing, D-1INSERT statement, 3-6, B-1, B-2

KKnown restrictions, 2-10

LLocking, database, 2-10LONG RAW data type, A-1

MMONEY data type, A-1

NNCHAR data type, A-1NULL values, 2-7NUMBER data type, A-1NUMERIC data type, A-2NVARCHAR data type, A-1NVL function, 3-5

OObjects, naming rules, 2-8ORA-02070, 2-11

Pparameters

gateway initialization fileHS_FDS_FETCH_ROWS, D-12

Passing commands to database, 2-12Pass-Through Feature, 3-6Pattern Matching, B-3PL/SQL, 2-16

RRAW data type, A-1REAL data type, A-2remote functions

referenced in SQL statements, D-3ROLLBACK

restrictions, 2-12ROWID, 2-13, 2-14

Ssavepoint support, 2-11SELECT statement, 3-6, B-1, C-1SMALL DATETIME data type, A-2SMALLINT data type, A-2Stored procedures, 2-12, 2-17

running in chained mode, 2-7Stored procedures in SQL Server, 2-2String functions, B-3SUM function, 3-5

TTIMESTAMP data type, A-2TINYINT data type, A-2Transaction modes, 2-7transactional capability, 2-11transactional integrity, 2-11

Index-3

TRUNCATE statement, B-1Two-phase commit, 2-11

UUPDATE statement, 2-14, 3-5, 3-6, B-2

VVARBINARY data type, 2-15, A-2VARCHAR data type, A-2

WWHERE CURRENT OF clause, 2-13

Index-4

Documents

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