Getting Started with INFORMIX-Universal Server

Transcription

1 Getting Started with INFORMIX-Universal Server Version 9.1 March 1997 Part No

2 Published by INFORMIX Press Informix Software, Inc Bohannon Drive Menlo Park, CA Copyright by Informix Software, Inc. or their subsidiaries, provided that portions may be copyrighted by third parties, as set forth in documentation. All rights reserved. The following are worldwide trademarks of Informix Software, Inc., or its subsidiaries, registered in the United States of America as indicated by, and in numerous other countries worldwide: INFORMIX ; INFORMIX -OnLine Dynamic Server ; DataBlade The following are worldwide trademarks of the indicated owners or their subsidiaries, registered in the United States of America as indicated by, and in numerous other countries worldwide: Novell, Inc.: Novell ; NetWare ; IPX/SPX UNIX System Laboratories: OPEN LOOK X/OpenCompany Ltd.: UNIX ; X/Open All other marks or symbols are registered trademarks or trademarks of their respective owners. Documentation Team: Barbara Daniell, Karin Kristenson, Jennifer Leland To the extent that this software allows the user to store, display, and otherwise manipulate various forms of data, including, without limitation, multimedia content such as photographs, movies, music and other binary large objects (blobs), use of any single blob may potentially infringe upon numerous different third-party intellectual and/or proprietary rights. It is the user's responsibility to avoid infringements of any such thirdparty rights. RESTRICTED RIGHTS/SPECIAL LICENSE RIGHTS Software and documentation acquired with US Government funds are provided with rights as follows: (1) if for civilian agency use, with Restricted Rights as defined in FAR ; (2) if for Dept. of Defense use, with rights as restricted by vendor's standard license, unless superseded by negotiated vendor license as prescribed in DFAR Any whole or partial reproduction of software or documentation marked with this legend must reproduce the legend. ii Getting Started with INFORMIX-Universal Server

3 Table of Contents Table of Contents Introduction About This Manual Organization of This Manual Types of Users Software Dependencies Assumptions About Your Locale Demonstration Database Major Features Documentation Conventions Typographical Conventions Icon Conventions Additional Documentation On-Line Manuals Printed Manuals Error Message Files Documentation Notes, Release Notes, Machine Notes Related Reading Compliance with Industry Standards Informix Welcomes Your Comments Chapter 1 Introducing INFORMIX-Universal Server Architecture Overview of Database Management Systems Relational Database Management Systems Object-Relational Database Management Systems Architectural Elements of Universal Server Client/Server Architecture Scalability High Performance Fault Tolerance and High Availability Distributed Databases Database Server Security

4 Chapter 2 Chapter 3 Introducing Universal Server Features Data Types Supported Built-In Data Types User-Defined Data Types Complex Data Types User-Defined Routines Access Methods Primary Access Methods Secondary Access Methods DataBlade Modules Large-Object Support Smart Large Objects Simple Large Objects Application-Programming Interfaces DataBlade API Global Language Support API DB-Access Support Dbschema Support Utility Enhancements Introducing Universal Server Kits INFORMIX-Universal Server Universal Database Server BladeManager LOB Locator DataBlade Module INFORMIX-DB Admin Kit for Microsoft Windows Environments. 3-5 SQL Editor BladeManager Schema Knowledge SetNet INFORMIX-DataBlade Developer s Kit for Microsoft Windows Environments BladeSmith BladePack BladeManager SQL Editor Schema Knowledge INFORMIX-Developer SDK for UNIX Development Components for the UNIX Environment Runtime Libraries for the UNIX Environment iv INFORMIX

5 INFORMIX-Developer SDK for Microsoft Windows Environments Development Components for the Microsoft Windows Environment Runtime Libraries for the Microsoft Windows Environment INFORMIX-Connect for UNIX Runtime Libraries Documentation Notes INFORMIX-Connect for Microsoft Windows Environments Runtime Libraries SetNet Documentation Notes Chapter 4 Chapter 5 Chapter 6 Getting Up and Running with Universal Server Migrating from a Previous Informix Database Server Getting Started Tasks Client Applications Supported by Universal Server Installing Universal Server Configuring the Database Server Environment Configuring the SQL API Environment Choosing a Database Type Making the Initial Connection to a Database Server Creating the Demonstration Database Getting Error Message Information Using Universal Server Documentation Who Uses Universal Server? Database Users Programmers Database Administrators Universal Server Administrators Universal Server Documentation Task Matrix Universal Server Documentation Matrix Universal Server Documentation INFORMIX-DB Admin Kit for Microsoft Windows Environments Documentation INFORMIX-DataBlade Developer s Kit for Microsoft Windows Environments Documentation INFORMIX-Developer SDK for UNIX Documentation INFORMIX-Developer SDK for Microsoft Windows Environments Documentation Table of Contents v

6 INFORMIX-Connect for UNIX INFORMIX-Connect for Microsoft Windows Environments Appendix A Environment Variables Index vi INFORMIX

7 Introduction Introduction About This Manual Organization of This Manual Types of Users Software Dependencies Assumptions About Your Locale Demonstration Database Major Features Documentation Conventions Typographical Conventions Icon Conventions Comment Icons Cross-Reference Icons Feature Icons Additional Documentation On-Line Manuals Printed Manuals Error Message Files Documentation Notes, Release Notes, Machine Notes Related Reading Compliance with Industry Standards Informix Welcomes Your Comments

8 2 INFORMIX

9 Read this introduction for an overview of the information provided in this manual and for an understanding of the documentation conventions used. About This Manual Getting Started with INFORMIX-Universal Server provides an overview of Universal Server architecture, introduces the major features of Universal Server, introduces Universal Server kits, and provides information to help you use the documentation that is included with each Universal Server kit. Organization of This Manual This manual includes the following chapters: This Introduction provides an overview of the manual and describes the documentation conventions used. Chapter 1, Introducing INFORMIX-Universal Server Architecture, provides an overview of database management systems and introduces Universal Server architecture. Chapter 2, Introducing Universal Server Features, introduces the features of Universal Server and identifies the primary book that contains detailed information about the features. Introduction 3

10 Types of Users Chapter 3, Introducing Universal Server Kits, describes the components of each Universal Server kit. Universal Server kits are: INFORMIX-Universal Server INFORMIX-DB Admin Kit for Microsoft Windows Environments INFORMIX-DataBlade Developer s Kit for Microsoft Windows Environments INFORMIX-Developer SDK for UNIX INFORMIX-Developer SDK for Microsoft Windows Environments INFORMIX-Connect for UNIX INFORMIX-Connect for Microsoft Windows Environments Chapter 4, Getting Up and Running with Universal Server, provides a list of the major tasks you need to perform to get Universal Server up and running. Chapter 5, Using Universal Server Documentation, contains a matrix that includes cross-references from tasks to the appropriate manual in the Universal Server documentation set. Chapter 6, Universal Server Documentation Matrix, contains descriptions of books provided with each Universal Server kit. Appendix A is a quick-reference list of all Universal Server environment variables. Types of Users This manual is written for database administrators, Universal Server administrators, client/application programmers, and database users. It assumed you understand the basic elements of a relational database. If you are unfamiliar with relational database concepts, review the Informix Guide to SQL: Tutorial. 4 Getting Started with INFORMIX-Universal Server

11 Software Dependencies Software Dependencies This manual assumes that you are using INFORMIX-Universal Server, Version 9.1, as your database server. In this manual, all instances of Universal Server refer to INFORMIX-Universal Server. Assumptions About Your Locale Informix products can support many languages, cultures, and code sets. All culture-specific information is brought together in a single environment, called a GLS (Global Language Support) locale. This manual assumes that you are using the default locale, en_us This locale supports U.S. English format conventions for dates, times, and currency. In addition, this locale supports the ISO code set, which includes the ASCII code set plus many 8-bit characters such as é, è, and ñ. If you plan to use nondefault characters in your data or your SQL identifiers, or if you want to conform to the nondefault collation rules of character data, you need to specify the appropriate nondefault locale(s). For instructions on how to specify a nondefault locale, additional syntax, and other considerations related to GLS locales, see the Guide to GLS Functionality. Demonstration Database The DB-Access utility, which is provided with your Informix database server products, includes a demonstration database called stores7 that contains information about a fictitious wholesale sporting-goods distributor. Sample command files are also included. Many examples in Informix manuals are based on the stores7 demonstration database. The stores7 database is described in detail and its contents are listed in Appendix A of the Informix Guide to SQL: Reference. The script that you use to install the demonstration database is called dbaccessdemo7 and is located in the $INFORMIXDIR/bin directory. For a complete explanation of how to create and populate the demonstration database on your database server, refer to the DB-Access User Manual. Introduction 5

12 Major Features Major Features The major features of INFORMIX-Universal Server are documented in Chapter 2, Introducing Universal Server Features. The Introduction to each Version 9.1 product manual contains a list of major features for that product. The Introduction to each manual in the Version 9.1 Informix Guide to SQL series contains a list of new SQL features. Major features for Version 9.1 Informix products also appear in release notes. Documentation Conventions This section describes the conventions that this manual uses. These conventions make it easier to gather information from this and other Informix manuals. The following conventions are covered: Typographical conventions Icon conventions 6 Getting Started with INFORMIX-Universal Server

13 Typographical Conventions Typographical Conventions This manual uses the following standard set of conventions to introduce new terms, illustrate screen displays, describe command syntax, and so forth. Convention KEYWORD italics boldface monospace KEYSTROKE Meaning All keywords appear in uppercase letters in a serif font. Within text, new terms and emphasized words appear in italics. Within syntax diagrams, values that you are to specify appear in italics. Identifiers (names of classes, objects, constants, events, functions, program variables, forms, labels, and reports), environment variables, database names, filenames, table names, column names, icons, menu items, command names, and other similar terms appear in boldface. Information that the product displays and information that you enter appear in a monospace typeface. Keys that you are to press appear in uppercase letters in a sans serif font. This symbol indicates the end of feature-, product-, platform-, or compliance-specific information. Tip: When you are instructed to enter characters or to execute a command, immediately press RETURN after the entry. When you are instructed to type the text or to press other keys, no RETURN is required. Icon Conventions Throughout the documentation, you will find text that is identified by several different types of icons. This section describes these icons. Introduction 7

14 Icon Conventions Comment Icons Comment icons identify warnings, important notes, or tips. This information is always displayed in italics. Icon Description The warning icon identifies vital instructions, cautions, or critical information. The important icon identifies significant information about the feature or operation that is being described. The tip icon identifies additional details or shortcuts for the functionality that is being described. Cross-Reference Icons Cross-reference icons indicate paragraphs that show where you can find more information about a topic. Icon Description Identifies paragraphs that contain cross references to other Informix manuals that provide additional information on a topic. 8 Getting Started with INFORMIX-Universal Server

15 Additional Documentation Feature Icons Feature icons identify paragraphs that contain feature-specific information. Icon Description GLS Identifies information that relates to the Informix Global Language Support (GLS) feature. These icons can apply to a row in a table, one or more paragraphs, or an entire section. A symbol indicates the end of the feature-specific information. Additional Documentation For additional information, you might want to refer to the following types of documentation: On-line manuals Printed manuals Error message files Documentation notes, release notes, and machine notes Related reading On-Line Manuals A CD that contains Informix manuals in electronic format is provided with your Informix products. You can install the documentation or access it directly from the CD. For information about how to install, read, and print online manuals, see either the installation guide for your product or the installation insert that accompanies the documentation CD. The documentation set that is provided on the CD describes Universal Server, its implementation of SQL, and its associated application-programming interfaces. For an overview of the manuals in the Universal Server documentation set, and Universal Server kit documentation, see Chapter 5, Using Universal Server Documentation. Introduction 9

16 Printed Manuals Printed Manuals The Universal Server documentation set describes Universal Server, its implementation of SQL, and its associated application-programming interfaces. In addition, Universal Server kits include documentation to support the various components of each kit. For an overview of the manuals in the Universal Server documentation set, and Universal Server kit documentation, see Chapter 6, Universal Server Documentation Matrix. To order printed manuals, call or send to Please provide the following information: The documentation that you need The quantity that you need Your name, address, and telephone number Error Message Files Informix software products provide ASCII files that contain all the Informix error messages and their corrective actions. To read the error messages in the ASCII file, Informix provides scripts that let you display error messages on the screen (finderr) or print formatted error messages (rofferr). For a detailed description of these scripts, see the Introduction to the Informix Error Messages manual. 10 Getting Started with INFORMIX-Universal Server

17 Documentation Notes, Release Notes, Machine Notes Documentation Notes, Release Notes, Machine Notes In addition to printed documentation, the following on-line files, located in the $INFORMIXDIR/release/en_us/0333 directory, supplement the information in this manual. On-Line File STARTDOC_9.1 SERVERS_9.1 IUNIVERSAL_9.1 Purpose The documentation-notes file describes features that are not covered in this manual or that have been modified since publication. The release-notes file describes feature differences from earlier versions of Informix products and how these differences might affect current products. This file also contains information about any known problems and their workarounds. The file listed contains the release notes for Universal Server. The machine-notes file describes any special actions that are required to configure and use Informix products on your computer. Machine notes are named for the product described. Please examine these files because they contain vital information about application and performance issues. Introduction 11

18 Related Reading Related Reading For additional technical information on database management, consult the following books: Object-Relational DBMSs: The Next Great Wave by Michael Stonebraker with Dorothy Moore (Morgan Kaufmann Publishers, Inc., 1996) An Introduction to Database Systems by C. J. Date (Addison- Wesley Publishing, 1995) Transaction Processing: Concepts and Techniques by Jim Gray and Andreas Reuter (Morgan Kaufmann Publishers, Inc., 1993) To learn more about the SQL language, consider the following books: A Guide to the SQL Standard by C. J. Date with H. Darwen (Addison-Wesley Publishing, 1993) Understanding the New SQL: A Complete Guide by J. Melton and A. Simon (Morgan Kaufmann Publishers, 1993) Informix manuals assume that you are familiar with your computer operating system. If you have limited experience with your operating system, consult your operating-system manual or a good introductory text before you read this manual. The following texts provide a good introduction to UNIX systems: Introducing the UNIX System V by R. Morgan and H. McGilton (McGraw-Hill Book Company, 1987) Learning the UNIX Operating System by G. Todino, J. Strang, and J. Peek (O Reilly & Associates, 1993) UNIX System V: A Practical Guide by M. Sobell (Benjamin/Cummings Publishing, 1995) 12 Getting Started with INFORMIX-Universal Server

19 Compliance with Industry Standards The following texts provide a good introduction to Windows NT: Using Windows NT Workstation 3.51 by Paul Sanna (Que, 1996) Microsoft Windows NT Resource Kit by Russ Blake (Microsoft Press, 1995) NT Server Management and Control by Kenneth L. Spencer (Prentice- Hall, 1995) Windows NT Administration by Marshall Brain and Shay Woodard (Prentice-Hall, 1994) Windows NT Network Programming by Ralph Davis (Addison-Wesley, 1994) Inside Windows NT by Helen Custer (Microsoft Press, 1993) Compliance with Industry Standards The American National Standards Institute (ANSI) has established a set of industry standards for SQL. Informix SQL-based products are fully compliant with SQL-92 Entry Level (published as ANSI X ), which is identical to ISO 9075:1992, on INFORMIX-Universal Server. In addition, many features of Universal Server comply with the SQL-92 Intermediate and Full Level and X/Open SQL CAE (common applications environment) standards. Introduction 13

20 Informix Welcomes Your Comments Informix Welcomes Your Comments Please tell us what you like or dislike about our manuals. To help us with future versions of our manuals, we want to know about corrections or clarifications that you would find useful. Include the following information: The name and version of the manual that you are using Any comments that you have about the manual Your name, address, and phone number Write to us at the following address: Informix Software, Inc. SCT Technical Publications Department 4100 Bohannon Drive Menlo Park, CA If you prefer to send , our address is: Or send a facsimile to the Informix Technical Publications Department at: We appreciate your feedback. 14 Getting Started with INFORMIX-Universal Server

21 Introducing INFORMIX- Universal Server Architecture Chapter 1 Overview of Database Management Systems Relational Database Management Systems Object-Relational Database Management Systems Architectural Elements of Universal Server Client/Server Architecture Scalability High Performance Raw Disk Management Memory Management Dynamic Thread Allocation Parallelization Fault Tolerance and High Availability Dbspace and Logical-Log Backups of Transaction Records Fast Recovery Mirroring High-Availability Data Replication Point-in-Time Restore Distributed Databases Database Server Security

22 1-2 INFORMIX

23 INFORMIX-Universal Server extends relational database technology to support more complex data types such as 2D and 3D images, sound, video, electronic documents, HTML pages, time-series data, and spatial data. INFORMIX-Universal Server starts with the building blocks of INFORMIX-OnLine Dynamic Server dynamic scalable architecture (DSA) and extends the capability of the relational database management system to an object-relational database management system. This section provides an overview of database management systems and then lists the building blocks that define the architecture of Universal Server. For information on the features specific to Universal Server, see Chapter 2, Introducing Universal Server Features. Introducing INFORMIX-Universal Server Architecture 1-3

24 Overview of Database Management Systems Overview of Database Management Systems Four fundamentally different technologies are available to manage data: file systems, relational database management systems (RDBMS), object-oriented database management systems (OODBMS), and object-relational database management systems (ORDBMS). Each has its own strengths that make it appropriate for particular classes of data management problems. Figure 1-1 illustrates the four database management systems. Queries Relational database management system Object-relational database management system Figure 1-1 Database Management System Grid (RDBMS) (ORDBMS) No queries File systems, video servers Object-oriented database management system (OODBMS) Simple data Complex data While file systems, video server database management systems, and objectoriented database management systems provide valid solutions to business applications that do not require query capabilities, they are not discussed in this section. This section concentrates on relational database management systems (such as INFORMIX-OnLine Dynamic Server) and object-relational database management systems (such as INFORMIX-Universal Server). 1-4 Getting Started with INFORMIX-Universal Server

25 Relational Database Management Systems Relational Database Management Systems Relational database management systems focus on high-speed, shortrunning queries and transactions on simple data. Simple data includes the following data types: Integer Floating-point number Character string, fixed or variable length Date and time, time interval Numeric and decimal Some relational database management systems (including INFORMIX-OnLine Dynamic Server) provide limited support for complex data, which is stored in binary large objects (blobs). However, blobs cannot be indexed, searched, or manipulated within the database server. The lack of complex data support in RDBMS has become a major hindrance to the development of new classes of applications. For example, how can an RDBMS handle the various kinds of complex data found today on the World Wide Web? How do you search for a song if you do not know the song name and only remember part of the tune? How do you find a picture when you do not know the artist but remember that the picture contains a red boat in a blue lake? You can find this kind of information if you extend the relational database management system so it can search and manipulate complex data. Object-Relational Database Management Systems Object-relational database management systems can manage complex data natively as objects which provides very high performance query and transaction to complex data. To accomplish this, you must have the ability to define new data structures and the functions that manipulate them. Informix extends INFORMIX-OnLine Dynamic Server to provide an ORDBMS named INFORMIX-Universal Server. Introducing INFORMIX-Universal Server Architecture 1-5

26 Architectural Elements of Universal Server Architectural Elements of Universal Server The following sections describe the architectural elements of Universal Server: Client/server architecture Scalability High performance Fault tolerance and high availability Distributed databases ANSI-compliant database support Database server security Client/Server Architecture Universal Server processes requests for data from client applications. It accesses the requested information from its databases and sends back the results. Accessing the database includes activities such as coordinating concurrent requests from multiple clients, performing read and write operations to the databases, and enforcing physical and logical consistency on the data. The client is an application program that a user runs to request information from a database. Client applications use Structured Query Language (SQL) to send data requests to Universal Server. (The implementation of SQL complies fully with the ANSI SQL-92 standard at the Entry Level.) Client programs include the DB-Access utility and programs that you write using INFORMIX-ESQL/C, C++, Java, and so on. When the client connects to Universal Server through an SQL statement, the client transparently accesses connectivity information contained in a file called sqlhosts. For more information on the SQL statements that Universal Server supports, see the Informix Guide to SQL: Syntax. For more information on how to define connectivity information in the sqlhosts file, see the INFORMIX-Universal Server Administrator s Guide. 1-6 Getting Started with INFORMIX-Universal Server

27 Scalability Scalability Universal Server enables you to scale resources in relation to the demands that applications place on the database server. The dynamic scalable architecture of Universal Server provides the following performance advantages for both single-processor and multiprocessor platforms: A small number of database server processes can service a large number of client application processes, producing the following benefits: Reduced operating-system overhead (fewer processes to run) Reduced overall memory requirements Reduced contention for resources within the RDBMS DSA provides more control over setting priorities and scheduling database tasks than the operating system does. Universal Server particularly exploits symmetric multiprocessing computer systems (SMPs). In a symmetric multiprocessing computer system, multiple CPUs (central processing units, or processors) all run a single copy of the operating system, sharing memory and communicating with each other as necessary. For more detailed information on the dynamic scalable architecture of Universal Server, see the INFORMIX-Universal Server Administrator s Guide. High Performance Universal Server achieves high performance through the following mechanisms: Raw disk management Memory management Dynamic thread allocation Parallelization Each of these mechanisms is explained in the following paragraphs. Introducing INFORMIX-Universal Server Architecture 1-7

28 High Performance Raw Disk Management Universal Server can use both UNIX file-system disk space and raw disk space. When Universal Server uses raw disk space, however, it performs its own disk management using raw devices. By storing tables on one or more raw devices instead of in a standard operating-system file system, Universal Server can manage the physical organization of data and minimize disk I/O. Doing so results in three performance advantages: Universal Server is not restricted by operating-system limits on the number of tables that can be accessed concurrently. Universal Server optimizes table access by guaranteeing that rows are stored contiguously. Universal Server eliminates operating-system I/O overhead by performing direct data transfer between disk and shared memory. If these issues are not a primary concern, you can also configure Universal Server to use regular operating-system files to store data. In this case, Universal Server manages the file contents, but the operating system manages the I/O. For more information on raw disk management, see the INFORMIX-Universal Server Administrator s Guide. Memory Management Universal Server provides various options to help you manage memory to optimize performance. Dynamically Sharing Memory All applications that use a single instance of Universal Server share data in the memory space of the database server. After one application reads data from a table, other applications can access whatever data is already in memory. Disk access, and the corresponding degradation in performance, might not occur because Universal Server adds memory dynamically as it needs it. The Universal Server administrator can also add segments to shared memory when necessary. 1-8 Getting Started with INFORMIX-Universal Server

29 High Performance Buffering Transactions You can determine where transactions are logged in Universal Server. Your logs can be buffered or unbuffered. Buffered logging holds transactions in memory until the buffer is full, regardless of when the transaction is committed. For more information on managing the various aspects of memory to increase performance, see the INFORMIX-Universal Server Performance Guide. Dynamic Thread Allocation Universal Server supports multiple client applications using a relatively few number of processes called virtual processors. A virtual processor is a multithreaded process that can serve multiple clients and, where necessary, run multiple threads to work in parallel for a single query. In this way, Universal Server provides a flexible architecture that is well suited for both on-line transaction processing (OLTP) and for decision-support applications. For more information on how virtual processors can dynamically allocate threads, see the INFORMIX-Universal Server Administrator s Guide. Parallelization Universal Server can allocate multiple threads to work in parallel on a single query. This feature is known as the parallel database query (PDQ) feature. Universal Server also allows a table to be fragmented over multiple disks. Fragmentation allows you to group rows within a table according to a distribution scheme. Universal Server stores the rows in separate database spaces (dbspaces) that you specify in a fragmentation strategy. A dbspace is a logical collection of one or more Universal Server chunks. Chunks represent specific regions of disk space. The PDQ feature is most effective when you use it with the fragmentation feature. For more information on how parallelization and fragmentation can enhance performance, see the INFORMIX-Universal Server Performance Guide. Introducing INFORMIX-Universal Server Architecture 1-9

30 Fault Tolerance and High Availability Fault Tolerance and High Availability Universal Server uses the following logging-and-recovery mechanisms to protect data integrity and consistency in the event of an operating-system or media failure: Dbspace and logical-log backups of transaction records Fast recovery Mirroring Data replication Point-in-time restore Dbspace and Logical-Log Backups of Transaction Records Universal Server provides you with the ability to back up the data that it manages and also store changes to the database server and data since the backup was performed. The changes are stored in logical-log files. Universal Server allows you to create backup tapes and logical-log backup tapes while users are accessing Universal Server. You can also use on-line archiving to create incremental backups. Incremental backups enable you to back up only data that has changed since the last backup, which reduces the amount of time that a backup would otherwise require. After a media failure, if critical data was not damaged (and Universal Server remains on-line), you can restore only the data that was on the failed media, leaving other data available during the restore Getting Started with INFORMIX-Universal Server

31 Fault Tolerance and High Availability Fast Recovery When Universal Server starts up, it checks if the physical log is empty because that implies that Universal Server shut down in a controlled fashion. If the physical log is not empty, Universal Server automatically performs an operation called fast recovery. Fast recovery automatically restores Universal Server databases to a state of physical and logical consistency after a system failure that might leave one or more transactions uncommitted. During fast recovery, Universal Server uses its logical log and physical log to perform the following operations: Restore the databases to their state at the last checkpoint Roll forward all committed transactions since the last checkpoint Roll back any uncommitted transactions Universal Server spawns multiple threads to work in parallel during fast recovery. Mirroring When you use disk mirroring, Universal Server writes data to two locations. Mirroring eliminates data losses due to media (hardware) crashes. If mirrored data becomes unavailable for any reason, the mirror of the data is accessed immediately and transparently to users. High-Availability Data Replication If your organization requires a high degree of availability, you can replicate Universal Server and its databases, running simultaneously on a second computer. Replicating Universal Server and its databases provides you with a backup system in the event of a catastrophic failure; if one site experiences a disaster, applications can be directed immediately to use the second database server in the pair. Running data replication also allows you to balance read-only applications (for example, decision-support applications) across both database servers in the data-replication pair. Introducing INFORMIX-Universal Server Architecture 1-11

32 Distributed Databases Point-in-Time Restore Universal Server allows users to restore data to a specified point in time. This feature allows you to restore the database after a catastrophic event to a particular point in time, perhaps immediately preceding the catastrophic event. For more information on fault tolerance and high availability, see the INFORMIX-Universal Server Administrator s Guide. Distributed Databases Universal Server allows you to query (and update) more than one database across multiple database servers within a single transaction. This ability is called distributed database processing. Distributed databases are useful because operations that access databases are often distributed into separate pieces, either organizationally, graphically, or both. Distributed databases use the two-phase commit protocol to ensure that transactions are uniformly committed or rolled back across multiple database servers. Distributed databases provide the following advantages: Local data can be kept where it is more easily maintained and is more frequently used Data from remote sites is available to all users For more information on distributed databases, see the INFORMIX-Universal Server Administrator s Guide Getting Started with INFORMIX-Universal Server

33 Database Server Security Database Server Security You can use the GRANT and REVOKE SQL statements to enforce database and table privileges. In addition to this type of security, you can add external communications support services in the form of a communications support module (CSM). The CSM provides access to the DCE 1.1 security service, a Kerberos 5-based security service. Kerberos allows a client application, on behalf of its user, to authenticate its identity to a server without sending data that would enable someone to impersonate the user. Universal Server also offers the ability to audit database events on a database-server-wide basis. Auditing enables you to track which users performed specific actions to particular objects at distinct times. You can use this information to monitor database activity for suspicious use, deter unscrupulous users, or even act as evidence of database server abuse. For more information on database server security, see the INFORMIX-Universal Server Administrator s Guide. For more information on auditing, see the INFORMIX-Universal Server Trusted Facility Manual. Introducing INFORMIX-Universal Server Architecture 1-13

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35 Introducing Universal Server Features Chapter 2 Data Types Supported Built-In Data Types User-Defined Data Types Opaque Type Distinct Type Complex Data Types Collection Type Row Type User-Defined Routines Access Methods Primary Access Methods Secondary Access Methods Generic B-Trees R-Trees DataBlade Modules Large-Object Support Smart Large Objects Simple Large Objects Application-Programming Interfaces DataBlade API Global Language Support API DB-Access Support Dbschema Support Utility Enhancements

36 2-2 INFORMIX

37 INFORMIX-Universal Server allows you to manage complex types of data such as 2D and 3D images, sound, video, electronic documents, HTML pages, time-series data, and spatial data. This chapter lists Universal Server features that allow you to manage and manipulate complex data. The features of Universal Server are: Data types supported Built-in User-defined Complex User-defined routines Access Methods Primary access methods Secondary access methods DataBlade modules Large-object support Application programming interfaces DB-Access support Dbschema support Utility enhancements Introducing Universal Server Features 2-3

38 Data Types Supported Data Types Supported Universal Server provides support for three data type categories: Built-in User-defined Complex Built-In Data Types Universal Server provides the following built-in data types: Character data types: CHAR, CHARACTER VARYING (or VARCHAR), and LVARCHAR The NCHAR and NVARCHAR data types also support storage of character data. Universal Server supports global languages. The Global Language Support (GLS) features let Universal Server handle different languages, cultural conventions, and code sets. The GLS feature provides support for the following language-related topics: Collation order of characters Definition of uppercase and lowercase conventions Non-ASCII characters, including multibyte characters Culture-specific formatting for numeric, monetary, date, and time values For more information on the GLS support, see the Guide to GLS Functionality. Numeric types Exact numeric types: DECIMAL, MONEY, SMALLINT, INTEGER, INT8, SERIAL, and SERIAL8 Approximate numeric types: SMALLFLOAT and FLOAT 2-4 Getting Started with INFORMIX-Universal Server

39 User-Defined Data Types Large-object data types Simple-large-object types: TEXT and BYTE Smart-large-object types: CLOB and BLOB For more information on smart-large-object types, see Large-Object Support on page Time data types: DATE, DATETIME, and INTERVAL Miscellaneous data type: BOOLEAN For a description of each of these data types, refer to the Informix Guide to SQL: Reference. User-Defined Data Types You can create user-defined data types to extend the database server and provide greater flexibility in the types of data you can store and manipulate. Universal Server introduces the following two new data types: opaque and distinct. Opaque Type An opaque type is a fundamental data type that stores a single value and cannot be divided into components by the database server. It is implemented as a C structure and a set of routines written in C that allow the database server to support the data type. C routines that support a new opaque type pass the contents of the structure to the database server to store in the database. The database server does not interpret the contents of the structure; it stores the memory contents, byte for byte, in the database. The support routines implement operations such as comparing two instances of a data type, converting an opaque type to another data type, or displaying an instancing of the data type. The database server calls the support routine supplied for an operation and passes the C structure or pointer to it in the parameter list. Introducing Universal Server Features 2-5

40 Complex Data Types Distinct Type A distinct type has the same storage representation as an existing opaque type but is distinguished by its name and cannot be substituted for the source data type. For example, a new distinct type decnum can be created with the same representation as real. All routines that operate on real values have database server-simulated counterparts for decnum values. However, decnum values and real values cannot be added, subtracted, or compared with one another without explicitly casting one value to the type of the other. A cast function converts one data type to another data type. For more information on user-defined data types, see Extending INFORMIX-Universal Server: Data Types. Complex Data Types A complex data type is usually a composite of other existing data types. For example, you might create a complex type whose components include builtin types, opaque types, distinct types, or other complex types. An important difference between complex types and user-defined types is that you can access and manipulate the individual components of a complex data type with SQL statements. 2-6 Getting Started with INFORMIX-Universal Server

41 Complex Data Types Collection Type A collection type is a group of elements of the same data type. Collection data types enable you to store and manipulate collections of data within a single row of a table. A collection type has two components: a type constructor and element type. Type constructors include sets, multisets, and lists. SET is a collection data type in which elements are not ordered and duplicates are not allowed. It is created with the SET constructor. LIST is a collection data type in which the elements are ordered and duplicates are allowed. It is created with the LIST constructor. MULTISET is a collection data type in which elements are not ordered and duplicates are allowed. It is created with the MULTISET constructor. Element type specifies the type of data that the collection can contain. The elements of a collection can be any data type except SERIAL and SERIAL8. Row Type A row type is a sequence of one or more elements called fields. Each field has a name and a data type. The fields of a row are comparable to the columns of a table, but there are important differences. There is no default clause on a field, you cannot define constraints on a field, and you cannot use fields with tables, only with row types. There are two kinds of row types: named row types and unnamed row types. Named Row Types A named row type is a group of fields that are defined under a single name. A field refers to a component of a row type. Once you create a named row type, the name that you assign to the row type represents a unique type within the database. Introducing Universal Server Features 2-7

42 Complex Data Types You can create a named row type when you want a type that acts as a container for component values that users need to access. For example, you might create a named row type to support address values. Users might need direct access to the individual component values of an address such as street, city, state, and postal code. When you create a named row type address type, users always have direct access to each of the fields. Unnamed Row Types An unnamed row type is a group of fields that are defined by their structure. Unlike the named row type, you can assign an unnamed row type to a table. Use an unnamed row type to define the type of a column or field only. Inheriting Properties Universal Server supports inheritance for named row types and typed tables. Inheritance is the process that allows a type or a table to acquire the properties of another type or table. Inheritance allows for incremental modification, so that a type or table can inherit a general set of properties and add properties that are specific to itself. Type inheritance Type inheritance applies to named row types only. You can use inheritance to group named row types into a type hierarchy. A type hierarchy provides the following advantages: It encourages modular implementation of your data model. It ensures consistent reuse of schema components. It ensures that no data fields are accidentally left out. It allows a type to inherit routines that are defined on another type. 2-8 Getting Started with INFORMIX-Universal Server

43 Complex Data Types Table inheritance Tables that are defined on named row types support table inheritance. Table inheritance is the property that allows a table to inherit the behavior (constraints, storage options, triggers, and so on) in the table hierarchy. A table hierarchy is the relationship you can define among tables. A table inheritance provides the following advantages: It encourages modular implementation of your data model. It ensures consistent reuse of schema components. It allows you to construct queries whose scope can be some or all of the tables in the table hierarchy. For more information on complex types, see the Informix Guide to SQL: Tutorial. Introducing Universal Server Features 2-9

44 User-Defined Routines User-Defined Routines A user-defined routine (UDR) is a routine that you define and register in the system catalog tables and that you can invoke by an SQL statement or another routine. You must create a user-defined routine to operate on user-defined and complex data types. A UDR can be either a function or a procedure. A function is a routine that optionally accepts a set of arguments and returns a set of values. You can use a function in SQL expressions. A procedure is a routine that optionally accepts a set of arguments and does not return any values. You cannot use a procedure in SQL expressions. A UDR can be one of the following routines: Stored Procedure Language (SPL) routine An SPL routine is any routine whose body is written in SPL. Informix SPL is an extension to SQL that provides flow control, such as looping and branching. External routine An external routine is any routine whose body is written in a language other than SPL (for example, C language). You use external routines typically to perform operations on user-defined data types. For more information on user-defined routines, see Extending INFORMIX-Universal Server: User-Defined Routines Getting Started with INFORMIX-Universal Server

45 Access Methods Access Methods Universal Server supports the following two types of access methods: Primary access methods Secondary access methods Primary Access Methods Universal Server supports external spaces (extspaces), which are storage spaces that Universal Server does not manage directly. You can specify an external space as the storage space for a table for which you create a primary access method. A primary access method is a set of database server functions to access and manipulate data stored inside a source that is external to Universal Server. Universal Server introduces the Virtual Table Interface (VTI) to facilitate the development of primary access methods. You can access any of the following types of data with a primary access method: Other vendors database tables Data stored in sequential files Remote data stored across a network Because primary access methods can be implemented as client applications, they typically do not require any direct interaction with low-level database server modules, making them relatively simpler to develop and support than new storage or indexing strategies. Primary access methods can unify all of the heterogeneous data that is distributed throughout an organization under a single object-relational system. VTI includes all the functions that an access method typically uses. You write and register a set of access-method purpose functions to access a remote database. These functions are registered with Universal Server when you issue the SQL statement CREATE ACCESS_METHOD. When you create the table, you specify the access method that will be used whenever the table is used in an SQL statement. For more information on using primary access methods, see the Informix Guide to SQL: Syntax and Extending INFORMIX-Universal Server: Data Types. Introducing Universal Server Features 2-11