Welcome
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
System administration
These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
Performance Guide
The HCL® Informix® Performance Guide describes how to configure and operate your HCL Informix database server to improve overall system throughput and to improve the performance of SQL queries.
Effect of configuration on CPU utilization
The combination of operating-system and Informix® configuration parameters can affect CPU utilization. You can change the settings of the Informix configuration parameters that directly affect CPU utilization, and you can adjust the settings for different types of workloads.
Configuration parameters and environment variables that affect CPU utilization
Some configuration parameters and environment variables affect CPU utilization. You might need to adjust the settings of these parameters and variables when you consider methods of improving performance.
Limiting PDQ resources in queries
The MAX_PDQPRIORITY configuration parameter limits the percentage of parallel database query (PDQ) resources that a query can use. Use MAX_PDQPRIORITY to limit the impact of large CPU-intensive queries on transaction throughput.

HCL Informix® V15.0.0 documentation
Welcome to the documentation for HCL Informix® 15.0.0 and related client tools and products.
Product overview
HCL Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.
Installing
These topics describe how to install HCL Informix® database servers, client products, and modules.
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
- System administration
  These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL Informix® database servers.
  - List of utilities
    HCL Informix® includes utilities and applications that you can use to perform administrative tasks and capture information about configuration and performance.
  - Administrator's Guide
    The HCL® Informix® Administrator's Guide provides the information required to administer HCL Informix.
  - Administrator's Reference
    The HCL® Informix® Administrator's Reference includes comprehensive descriptions of HCL Informix configuration parameters, the system-monitoring interface (SMI) tables in the sysmaster database, the syntax of database server utilities such as onmode and onstat, logical-log records, disk structures, event alarms, and unnumbered error messages.
  - DB-Access User's Guide
    The HCL® Informix® DB-Access User's Guide describes how to use the utility to access, modify, and retrieve information from HCL Informix database servers.
  - High-Performance Loader User's Guide
    The describes how to use the HCL Informix® to load and unload large quantities of data efficiently to or from Informix databases.
  - Performance Guide
    The HCL® Informix® Performance Guide describes how to configure and operate your HCL Informix database server to improve overall system throughput and to improve the performance of SQL queries.
    - Performance basics
      Performance measurement and tuning issues and methods are relevant to daily database server administration and query execution.
    - Performance monitoring and the tools you use
      You can use performance monitoring tools to create a performance history, to monitor database resources at scheduled times, or to monitor ongoing transaction or query performance.
    - Effect of configuration on CPU utilization
      The combination of operating-system and Informix® configuration parameters can affect CPU utilization. You can change the settings of the Informix configuration parameters that directly affect CPU utilization, and you can adjust the settings for different types of workloads.
      - UNIX™ configuration parameters that affect CPU utilization
        Your database server distribution includes a machine notes file that contains recommended values for UNIX™ configuration parameters. Because the UNIX parameters affect CPU utilization, you should compare the values in the machine notes file with your current operating-system configuration.
      - Windows™ configuration parameters that affect CPU utilization
        The Informix® distribution includes a machine notes file that contains recommended values for Informix configuration parameters on Windows™. Compare the values in this file with your current ONCONFIG configuration file settings.
      - Configuration parameters and environment variables that affect CPU utilization
        Some configuration parameters and environment variables affect CPU utilization. You might need to adjust the settings of these parameters and variables when you consider methods of improving performance.
        Specifying virtual processor class information
        Use the VPCLASS configuration parameter to specify a class of virtual processors, the number of virtual processors that the database server should start for a specific class, and the maximum number allowed.
        Setting the MULTIPROCESSOR configuration parameter when using multiple CPU VPs
        If you are running multiple CPU VPs, set the MULTIPROCESSOR configuration parameter to 1. When you set MULTIPROCESSOR to 1, the database server performs locking in a manner that is appropriate for a multiprocessor. Otherwise, set this parameter to 0.
        Setting the SINGLE_CPU_VP configuration parameter when using one CPU VP
        If you are running only one CPU VP, set the SINGLE_CPU_VP configuration parameter to 1. Otherwise, set this parameter to 0.
        Optimizing access methods
        The OPTCOMPIND configuration parameter helps the query optimizer choose an appropriate access method for your application. When the optimizer examines join plans, OPTCOMPIND indicates the preferred method for performing the join operation for an ordered pair of tables.
        Limiting PDQ resources in queries
        The MAX_PDQPRIORITY configuration parameter limits the percentage of parallel database query (PDQ) resources that a query can use. Use MAX_PDQPRIORITY to limit the impact of large CPU-intensive queries on transaction throughput.
        Limiting the performance impact of CPU-intensive queries
        The DS_MAX_QUERIES configuration parameter specifies a maximum number of decision-support queries that can run at any one time. Queries with a low PDQ priority use proportionally fewer resources, so a larger number of those queries can run simultaneously. You can use the DS_MAX_QUERIES configuration parameter to limit the performance impact of CPU-intensive queries.
        Limiting the number of PDQ scan threads that can run concurrently
        The DS_MAX_SCANS configuration parameter limits the number of PDQ scan threads that can run concurrently. This configuration parameter prevents the database server from being flooded with scan threads from multiple decision-support queries.
        Configuring poll threads
        The NETTYPE configuration parameter configures poll threads for each connection type that your instance of the database server supports. If your database server instance supports connections over more than one interface or protocol, you must specify a separate NETTYPE configuration parameter for each connection type.
        Enabling fast polling
        You can use the FASTPOLL configuration parameter to enable or disable fast polling of your network, if your operating-system platform supports fast polling. Fast polling is beneficial if you have a large number of connections.
      - Network buffer pools
        The sizes of buffers for TCP/IP connections affect memory and CPU utilization. Sizing these buffers to accommodate a typical request can improve CPU utilization by eliminating the need to break up requests into multiple messages.
      - Virtual processors and CPU utilization
        While the database server is online, you can start and stop virtual processors (VPs) that belong to certain classes.
      - Connections and CPU utilization
        Some applications have a large number of client/server connections. Opening and closing connections can consume a large amount of system CPU time.
    - Effect of configuration on memory utilization
      The combination of operating-system and Informix® configuration parameters can affect memory utilization.
    - Table performance considerations
      Some performance issues are associated with unfragmented tables and table fragments.
    - Boosted Partition Free Space Caches (PFSC)
    - Indexes and index performance considerations
      Informix® provides several types of indexes. Some performance issues are associated with indexes.
    - Locking
      The database server uses locks, which can affect concurrency and performance. You can monitor and administer locks.
    - Fragmentation guidelines
      One of the most frequent causes of poor performance in relational database systems is contention for data that resides on a single I/O device. Proper fragmentation of high-use tables can significantly reduce I/O contention. These topics discuss the performance considerations that are involved when you use table fragmentation.
    - Queries and the query optimizer
      These topics describe query plans, explain how the database server manages query optimization, and discuss factors that you can use to influence the query plan. These topics also describe performance considerations for SPL routines, the UDR cache, and triggers.
    - Optimizer directives
      Optimizer directives are comments that tell the query optimizer how to execute a query. You can use optimizer directives to improve query performance.
    - Parallel database query (PDQ)
      You can manage how the database server performs PDQ and you can monitor the resources that the database server uses for PDQ.
    - Improving individual query performance
      You can test, monitor, and improve queries.
    - Appendix
  - SNMP Subagent Guide
    The describes the Simple Network Management Protocol (SNMP) and the software that you need to use SNMP to monitor and manage HCL Informix® database servers and databases.
- Backup and Restore Guide
  The HCL® Informix® Backup and Restore Guide describes how to use the HCL Informix and ontape utilities to back up and restore database server data. These utilities enable you to recover your databases after data is lost or becomes corrupted due to hardware or software failure or accident.
- Enterprise Replication
  The describes the concepts of data replication using HCL Informix® Enterprise Replication, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.
Migrating and upgrading
You can upgrade to the 15.0.0 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Embedding Informix®
When you embed HCL Informix®, you can use enterprise-class high-availability and high performance with embeddability features such as easy programmability, a small disk and memory footprint, and silent deployment.
Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
Data warehousing
In addition to designing and implementing Informix® dimensional databases, you can use tools to create data warehouse applications and optimize your data warehouse queries.
Designing databases
The first step in creating a relational database is to construct a data model, which is a precise, complete definition of the data you want to store. After you prepare your data model, you must implement it as a database and tables. To implement your data model, you first select a data type for each column and then you create a database and tables and populate the tables with data. You can also implement fragmentation strategies and control access to your data.
JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
Troubleshooting HCL Informix®
Several troubleshooting techniques, tools, and resources are available for resolving problems that you encounter in your HCL Informix® database server environment.

Limiting PDQ resources in queries

The MAX_PDQPRIORITY configuration parameter limits the percentage of parallel database query (PDQ) resources that a query can use. Use MAX_PDQPRIORITY to limit the impact of large CPU-intensive queries on transaction throughput.

About this task

To limit the impact of large CPU-intensive queries on transaction throughput

Procedure

Set the value of the MAX_PDQPRIORITY configuration parameter to an integer that represents a percentage of the following PDQ resources that a query can request:

Memory
CPU VPs
Disk I/O
Scan threads

Example

When a query requests a percentage of PDQ resources, the database server allocates the MAX_PDQPRIORITY percentage of the amount requested, as the following formula shows:

Resources allocated = PDQPRIORITY/100 * MAX_PDQPRIORITY/100

For example, if a client uses the SET PDQPRIORITY 80 statement to request 80 percent of PDQ resources, but MAX_PDQPRIORITY is set to 50, the database server allocates only 40 percent of the resources (50 percent of the request) to the client.

For decision support and online transaction processing (OLTP), setting MAX_PDQPRIORITY allows the database server administrator to control the impact that individual decision-support queries have on concurrent OLTP performance. Reduce the value of MAX_PDQPRIORITY when you want to allocate more resources to OLTP processing. Increase the value of MAX_PDQPRIORITY when you want to allocate more resources to decision-support processing.

What to do next

For more information about how to control the use of PDQ resources, see The allocation of resources for parallel database queries.