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Contents

About This Manual

Software Dependencies

Assumptions About Your Locale

Demonstration Databases

Documentation Conventions

Typographical Conventions

Feature, Product, and Platform

Syntax Diagrams

Example Code Conventions

Additional Documentation

Installation Guides

Informix Error Messages

Compliance with Industry Standards

IBM Welcomes Your Comments

The Database Server

Introducing the Database Server

In This Chapter

Database Server Users

Application Developers

Database Administrators

Database Server Administrators

Database Server Operators

Extended Parallel Server

Client/Server Architecture

Dynamic Scalable Architecture

High Performance

Fault Tolerance

Database Server Security

Year 2000 Compliance

Extended Parallel-Processing Architecture

Extended Multithreaded Operation

Extended Scalability

Extended Client/Server Operations

Extended Dynamic Shared-Memory Management

Direct Disk Access

Single Point of Administration

Control of Resources in Parallel

Overview of Database Server Administration

Database Server Administrator

Configuration Tasks

Managing Disk Space

Managing Database-Logging Status

Managing the Logical Log

Managing the Physical Log

Using Mirroring

Managing Shared Memory

Managing Virtual Processors

Managing Parallel Database Query

Backing Up Data and Logical-Log Files

Monitoring Database Server Activity

Checking for Consistency

Summary of Administration Tasks

Monitoring Database Server Activity

Sources of Information for Monitoring

onutil CHECK Utility

Installing and Configuring the Database Server

Planning for the Database Server

Considering Your Priorities

Considering Your Environment

Configuring the Operating System

Modifying UNIX Kernel Parameters

Preparing the Operating System for the Database Server

Allocating Disk Space

Creating a Raw Device or Unbuffered File

Creating Standard Device Names

Setting Permissions, Ownership, and Group

Setting Up Disk Access Across Nodes

Installing the Database Server

Using Multiple Residency

Upgrading the Database Server

Setting Environment Variables

Required Environment Variables

Global Language Support

Other Environment Variables

Environment Variable Files

Configuring Connectivity

The sqlhosts File

Preparing the ONCONFIG Configuration File

Creating a Configuration File

Starting and Administering the Database Server

Preparing to Connect to Applications

Configuring the Database Server Page Size

Starting the Database Server and Initialize Disk Space

Performing Administrative Tasks

Setting Up Your Storage Manager and Storage Devices

Creating Storage Spaces

Monitoring Configuration Information

Using Command-Line Utilities

Configuration Parameters

Disk-Space Parameters

Mirror of Root Dbspace

Number of Storage Spaces

Other Space-Management Parameters

Database Server Identification Parameters

Logging Parameters

Storage-Space and Logical-Log Backups

Message-Log Parameters

Shared-Memory Parameters

Shared-Memory Size Allocation

Shared-Memory Space Allocation

Shared-Memory Buffer Control

Decision-Support Parameters

Database Server Process Parameters

Processor Affinity

Restore Parameters

Event-Alarm Parameters

Dump Parameters

Coserver Parameters

Specialized Parameters

Coserver Configuration

Configuring Multiple Coservers

Global Configuration Parameters

Coserver-Specific Configuration Parameters

Platform-Specific Configuration Parameters

Organizing the Configuration File

Setting Storage-Manager Parameters for ON-Bar

Choosing a Coserver Configuration

Single Coserver on a Single-Node Platform

Multiple Coservers on a Single-Node Platform

Single Coservers on Each Node of a Multiple-Node Platform

Multiple Coservers on Each Node of a Multiple-Node Platform

Managing Coservers

Adding Coservers

Customizing the Coserver Definition

Using the Default Cogroups

Creating User-Defined Cogroups

Enabling and Disabling Specific-Purpose Coservers

Removing Specific-Purpose Coservers

Defining Cogroups

Modifying Cogroups

Monitoring Coserver Activities

Creating and Loading Tables Fragmented Across Coservers

Client/Server Communications

Client/Server Architecture

Network Protocol

Network Programming Interface

Database Server Connection

Multiplexed Connection

Connections That the Database Server Supports

Local Connections

Coserver Client Connections

Communication Support Services

IBM Informix Password Communication Support Module

Connectivity Files

Network-Configuration Files

Network-Security Files

CSM Configuration File

The sqlhosts File

The sqlhosts Information

Connectivity Information

Group Information

Alternatives for TCP/IP Connections

ONCONFIG Parameters for Connectivity

COSERVER Configuration Parameter

DBSERVERNAME Configuration Parameter

DBSERVERALIASES Configuration Parameter

NETTYPE Configuration Parameter

Environment Variables for Network Connections

Examples of Client/Server Configurations

Using a Shared-Memory Connection

Using a Local-Loopback Connection

Using a Network Connection

Using Multiple Connection Types

Accessing Multiple Database Servers

Multiple Residency

Benefits of Multiple Residency

How Multiple Residency Works

The Role of the ONCONFIG Environment Variable

The Role of the SERVERNUM Configuration Parameter

Using Multiple Residency

Planning for Multiple Residency

Creating a New Database Server

Prepare a Configuration File

Set the ONCONFIG Environment Variable

Edit the New Configuration File

Add Connection Information

Update the sqlhosts File

Initialize Disk Space

Prepare Dbspace and Logical-Log Backup Environment

Update the Operating-System Boot File

Check INFORMIXSERVER Environment Variables for Users

Modes and Initialization

Managing Database Server Operating Modes

Database Server Operating Modes

Initializing Disk Space

Changing Database Server Operating Modes

Users Permitted to Change Modes

From Offline to Quiescent

From Offline to Microkernel

From Offline to Online

From Quiescent to Online

Gracefully from Online to Quiescent

Immediately from Online to Quiescent

From Any Mode Immediately to Offline

Initializing the Database Server

Types of Initialization

Initializing the Database Server

Initialization Steps

Process Configuration File

Create Shared-Memory Portions

Initialize Shared-Memory Structures

Initialize Disk Space

Start All Required Virtual Processors

Make Necessary Conversions

Initiate Fast Recovery

Initiate a Checkpoint

Document Configuration Changes

Create the oncfg_servername.servernum File

Drop Temporary Tblspaces

Set Forced Residency If Specified

Return Control to User

Prepare SMI Tables

Disk, Memory, and Process Management

Virtual Processors and Threads

Virtual Processors

Types of Virtual Processors

Advantages of Virtual Processors

How Virtual Processors Service Threads

Control Structures

Context Switching

Virtual-Processor Classes

CPU Virtual Processors

Disk I/O Virtual Processors

Network Virtual Processors

First-In-First-Out Virtual Processor

Communications Support Module Virtual Processor

Miscellaneous Virtual Processor

Managing Virtual Processors

Setting Virtual-Processor Configuration Parameters

Setting Virtual-Processor Configuration Parameters with a Text Editor

Starting and Stopping Virtual Processors

Adding Virtual Processors in Online Mode

Monitoring Virtual Processors

Monitoring Virtual Processors with Command-Line Utilities

Monitoring Virtual Processors with SMI Tables

Shared-Memory Use

Shared-Memory Allocation

Shared-Memory Size

Action to Take If SHMTOTAL Is Exceeded

Processes That Attach to Shared Memory

How a Client Attaches to the Communications Portion

How Utilities Attach to Shared Memory

How Virtual Processors Attach to Shared Memory

Resident Shared-Memory Segments

Resident Portion of Shared Memory

Shared-Memory Header

Shared-Memory Buffer Pool

Logical-Log Buffer

Physical-Log Buffer

Virtual Portion of Shared Memory

Management of the Virtual Portion of Shared Memory

Components of the Virtual Portion of Shared Memory

Communications Portion of Shared Memory

Concurrency Control

Shared-Memory Mutexes

Shared-Memory Buffer Locks

Database Server Thread Access to Shared Buffers

Configuring the Database Server to Read Ahead

Database Server Thread Access to Buffer Pages

Flushing Data to Disk

Events That Prompt Flushing of Buffer-Pool Buffers

Flushing Before-Images First

Flushing the Physical-Log Buffer

Synchronizing Buffer Flushing

Describing Flushing Activity

Flushing the Logical-Log Buffer

Buffering Simple-Large-Object Data Types

Blobpages Do Not Pass Through Shared Memory

TEXT and BYTE Objects Are Created Before the Data Row Is Inserted

Tracking Blobpages

Memory Use on 64-Bit Platforms

Managing Shared Memory

Setting Operating-System Shared-Memory Configuration Parameters

Maximum Shared-Memory Segment Size

Maximum Number of Shared-Memory Identifiers

Shared-Memory Lower-Boundary Address

Maximum Amount of Shared Memory for One Process

Setting Database Server Shared-Memory Configuration Parameters

Setting Parameters for Resident Shared Memory with a Text Editor

Tuning Parameters for Resident Shared Memory with onutil

Setting Parameters for Virtual Shared Memory with a Text Editor

Tuning Parameters for Virtual Shared Memory with onutil

Setting Parameters for Shared-Memory Performance Options with a Text Editor

Tuning Parameters for Shared-Memory Performance Options with onutil

Reinitializing Shared Memory

Turning Residency On or Off for Resident Shared Memory

Turning Residency On or Off in On-Line Mode

Turning Residency On or Off for the Next Time You Reinitialize Shared Memory

Adding a Segment to the Virtual Portion of Shared Memory

Monitoring Shared Memory

Monitoring Shared-Memory Segments

Monitoring the Shared-Memory Profile

Monitoring Buffers

Monitoring Buffer-Pool Activity

Monitoring Latches

Overview of Data Storage

Physical Units of Storage

Disk Allocation for Chunks

Logical Units of Storage

Temporary Tables

Table Fragmentation and Data Storage

Amount of Disk Space Needed to Store Data

Size of the Root Dbspace

Amount of Space That Databases Require

Disk-Layout Guidelines

Dbspace and Chunk Guidelines

Table-Location Guidelines

Sample Disk Layouts

Sample Layout When Performance Is Highest Priority

Sample Layout When Availability Is Highest Priority

Logical-Volume Manager

Managing Disk Space

Initializing Disk Space

Allocating Disk Space

Specifying an Offset

Allocating a File for Disk Space on UNIX

Allocating Raw Disk Space on UNIX

Configuring Disk Space for Multiple Coservers

Creating Standard Device Names

Setting Up Disk Access Across Nodes

Backing Up After You Change the Physical Schema

Creating a Dbspace

Specifying Pathnames for Dbspaces

Specifying Names and Maximum Number of Storage Spaces

Backing Up the New Dbspace

Creating a Temporary Dbspace

Creating a Dbspace with onutil

Creating Dbslices

Naming Dbslices

Increasing the Number of Dbslices

Backing Up the New Dbslice

Altering a Dbslice

Increasing the Maximum Number of Dbspaces, Chunks, or Dbslices

Adding a Chunk to a Dbspace

Backing Up the New Chunk

Naming Chunks and Storage Spaces

Limiting Chunk Size and Number

Loading Data Into a Table

Changing the Status of a dbspace

Toggling Between Read-Only and Operational Mode

Toggling Between Online and Offline Mode

Dropping a Chunk

Verifying Whether a Chunk Is Empty

Dropping a Chunk from a Dbspace with onutil

Dropping a Storage Space

Preparing to Drop a Storage Space

Backing Up After Dropping a Storage Space

Dropping a Mirrored Storage Space

Dropping a Dbspace with onutil

Dropping Dbslices

Skipping Inaccessible Fragments

Using the DATASKIP Configuration Parameter

Using onutil to modify DATASKIP

Using onstat to Check Dataskip Status

Using the SQL Statement SET DATASKIP

Effect of the Dataskip Feature on Transactions

Determining When to Use Dataskip

Monitoring Fragmentation Use

Displaying Databases

Using SMI Tables

Monitoring the Database Server for Disabling I/O Errors

Using the Message Log to Monitor Disabling I/O Errors

Using Event Alarms to Monitor Disabling I/O Errors

Monitoring Disk Usage

Monitoring Chunks

Monitoring Tblspaces and Extents

Monitoring Simple Large Objects in a Dbspace

No Compression of TEXT and BYTE Data Types

Table Fragmentation and PDQ

Fragmentation Goals

Responsibility for Fragmentation

Fragmentation Strategies

SQL Statements That Perform Fragmentation Tasks

Parallel Database Query

Structure of a PDQ Query

OLTP Applications

Decision-Support Applications

Database Server Use of PDQ

Resource Grant Manager

Fragmentation Enhancement to PDQ

How the Database Server Balances Workload

Resource Allocation with PDQ

Parameters for Controlling PDQ

Loading with External Tables for Extended Parallel Server

Getting an Overview of High-Performance Loading

Loading and UnLoading Data

Data-Format Conversion

File Types and Formats

Starting to Load and Unload Data

Specifying the External Table

Loading Data in Express Mode

Loading Data in Deluxe Mode

Loading, Unloading, and Reorganizing Data

Loading from a Delimited File with Unchanged Columns

Unloading to a Delimited File

Mapping Columns to Other Columns

Unloading to an Informix Data File

Loading Between Tables That Have the Same Schema

Loading from a Fixed-ASCII File

Unloading to a Fixed-ASCII File

Loading from an IBM Fixed-EBCDIC File

Loading from and Unloading to a Named Pipe

Adding an End-of-Line Character to a Fixed-ASCII File

Loading Values into Serial Columns

Loading Data Warehousing Tables

Loading Simple Large Objects

Formats for Simple Large Objects

Loading Simple Large Objects from an External Table

Using Pipe Staging

Monitoring the Load or Unload Operations

Monitoring Frequent Loads and Unloads

Monitoring FIFO Virtual Processors

Monitoring Loads and Unloads of Data

Recovering After Errors

Recoverability of Table Types

Logging and Log Administration

Database Server Processes That Require Logging

Transaction Logging

Database Server Activity That Is Logged

Activity That Is Always Logged

Activity Logged for Databases with Transaction Logging

Logging and Nonlogging Tables

Use of Logging Tables

Use of Nonlogging Tables

Activity That Is Not Logged

Database-Logging Status

Unbuffered Transaction Logging

Buffered Transaction Logging

ANSI-Compliant Transaction Logging

Databases with Different Log-Buffering Status

Settings or Changes for Logging Status or Mode

Managing Database-Logging Status

Changing Database-Logging Status

Modifying Database-Logging Status with ondblog

Changing Buffering Status with ondblog

Canceling a Logging Mode Change with ondblog

Making a Database ANSI Compliant with ondblog

Modifying the Table-Logging Status

Altering a Table to Turn Off Logging

Altering a Table to Turn On Logging

Creating a Nonlogging Temporary Table

Monitoring Transaction Logging

Monitoring Transaction Logging with SMI Tables

Monitoring Transaction Logging with System Catalog Tables

Logical-Log Files

Logical-Log Administration

Logical-Log Files on a Coserver

Size of the Logical Log

Performance Considerations

Long-Transaction Considerations

Size and Number of Logical-Log Files

Location of Logical-Log Files

Identification of Logical-Logs

Status Flags of Logical-Log Files

Backup of Logical-Log Files

Logical-Log Restore

Point-In-Time Restore

Freeing of Logical-Log Files

Database Server Attempt to Free a Log File

Action If the Next Logical-Log File Is Not Free

Logical Log and Long Transactions

Logging Process

Dbspace Logging

Managing Logical-Log Files

Adding a Logical-Log File or Logslice

Adding a Logical-Log File or Logslice with onutil

Altering a Logslice

Dropping a Logical-Log File or Logslice

Dropping a Logical-Log File or Logslice with onutil

Moving a Logical-Log File to Another Dbspace

Changing the Size of Logical-Log Files

Using onutil SET to configure the LOGSIZE parameter

Using onutil to replace Log Files or Logslices

Changing Logical-Log Configuration Parameters

Switching to the Next Logical-Log File

Monitoring Logging Activity

Monitoring the Logical Log for Fullness

Using SMI Tables

Monitoring Log-Backup Status

Displaying Logical-Log Records

Physical Logging

Physical Logging

Purpose of Physical Logging

Database Server Activity That Is Physically Logged

Size and Location of the Physical Log

Limit to the Size of the Physical Log

Location of the Physical Log

Details of Physical Logging

Page Is Read into the Shared-Memory Buffer Pool

A Copy of the Page Buffer Is Stored in the Physical-Log Buffer

Change Is Reflected in the Data Buffer

Physical-Log Buffer Is Flushed to the Physical Log

Page Buffer Is Flushed

When a Checkpoint Occurs

How the Physical Log Is Emptied

Managing the Physical Log

Changing the Physical-Log Location and Size

Reasons to Change the Physical-Log Location and Size

Preparing to Make the Changes

Checking For Adequate Contiguous Space

Using a Text Editor to Change Physical-Log Location or Size

Monitoring Physical and Logical Logging Activity

Using Command-Line Utilities

Using SMI Tables

Checkpoints and Fast Recovery

How the Database Server Achieves Data Consistency

Critical Sections

Full Checkpoint

Fuzzy Checkpoint

Events That Initiate a Fuzzy Checkpoint

Events That Initiate a Full Checkpoint

Forcing a Full Checkpoint

Forcing a Fuzzy Checkpoint

Sequence of Events in a Checkpoint

Backup and Restore Considerations

Time Stamps on Disk Pages

Time Stamps on Logical-Log Pages

Need for Fast Recovery

Situations When Fast Recovery Is Initiated

Details of Fast Recovery After A Full Checkpoint

Details of Fast Recovery After A Fuzzy Checkpoint

Fast Recovery of Tables

Monitoring Checkpoint Information

Using onstat Options

Using SMI Tables

Fault Tolerance

Benefits of Mirroring

Costs of Mirroring

Consequences of Not Mirroring

Alternatives to Mirroring

Mirroring Process

Creation of a Mirror Chunk

Mirror Status Flags

Actions During Processing

Result of Stopping Mirroring

Structure of a Mirror Chunk

Using Mirroring

Steps Required for Mirroring Data

Enabling Mirroring

Changing the MIRROR Parameter with ONCONFIG

Allocating Disk Space for Mirrored Data

Relinking a Chunk to a Device After a Disk Failure

Using Mirroring

Mirroring the Root Dbspace During Initialization

Changing the Mirror Status

Taking Down a Mirror Chunk

Ending Mirroring

Ending Mirroring with onutil

Managing Mirroring in Extended Parallel Server

Starting Mirroring for Unmirrored Dbspaces

Starting Mirroring for New Dbspaces and Dbslices

Adding Mirror Chunks to a Dbspace

Taking Down a Mirror Chunk

Recovering a Mirror Chunk

Modifying Mirroring of All Root Dbspaces

Ending Mirroring for a Dbspace

Consistency Checking

Performing Periodic Consistency Checking

Verifying Consistency

Monitoring for Data Inconsistency

Retaining Consistent Level-0 Backups

Dealing with Corruption

Symptoms of Corruption

Fixing Index Corruption

I/O Errors on a Chunk

Collecting Diagnostic Information

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