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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 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.
Table performance considerations
Some performance issues are associated with unfragmented tables and table fragments.
Estimating table size
You can calculate the approximate sizes (in disk pages) of tables.

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 Informix® Administrator's Guide provides the information required to administer HCL Informix.
  - Administrator's Reference
    The 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 Informix® DB-Access User's Guide describes how to use the DB-Access utility to access, modify, and retrieve information from 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 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.
    - 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.
      - Placing tables on disk
        Tables that the database server supports reside on one or more portions of one or more disks. You control the placement of a table on disk when you create it by assigning it to a dbspace.
      - Estimating table size
        You can calculate the approximate sizes (in disk pages) of tables.
        Estimating data pages
        How you estimate the data pages of a table depends on whether that table contains fixed-length or variable-length rows.
        Estimating pages that simple large objects occupy
        You can estimate the total number of pages for all simple large objects, or you can estimate the number of pages based on the median size of the simple large objects.
      - Managing the size of first and next extents for the tblspace tblspace
        The tblspace tblspace is a collection of pages that describe the location and structure of all tblspaces in a dbspace. Each dbspace has one tblspace tblspace. When you create a dbspace, you can use the TBLTBLFIRST and TBLTBLNEXT configuration parameters to specify the first and next extent sizes for the tblspace tblspace in a root dbspace.
      - Managing sbspaces
        An sbspace is a logical storage unit composed of one or more chunks that store smart large objects. You can estimate the amount of storage needed for smart large objects, improve metadata I/O, monitor sbspaces, and change storage characteristics.
      - Managing extents
        As you add rows to a table, the database server allocates disk space in units called extents. Each extent is a block of physically contiguous pages from the dbspace. Even when the dbspace includes more than one chunk, each extent is allocated entirely within a single chunk, so that it remains contiguous.
      - Storing multiple table fragments in a single dbspace
        You can store multiple fragments of the same table or index in a single dbspace, thus reducing the total number of dbspaces needed for a fragmented table. You must specify a name for each fragment that you want to store in the same dbspace. Storing multiple table or index fragments in a single dbspace simplifies the management of dbspaces.
      - Displaying a list of table and index partitions
        Use the onstat -g opn option to display a list of the table and index partitions, by thread ID, that are currently open in the system.
      - Changing tables to improve performance
        You can change tables to improve performance by dropping indexes, attaching or detaching fragments, and altering table definitions. You can also create databases for decision-support applications by unloading and loading tables in OLTP databases.
      - Denormalize the data model to improve performance
        You might need to denormalize the data model to reduce overhead and optimize performance.
      - Reduce disk space in tables with variable length rows
        You can enable the database server to insert more rows per page into tables with variable-length rows, if you set the MAX_FILL_DATA_PAGES configuration parameter to 1. Allowing more variable length rows per page has advantages and disadvantages.
      - Reduce disk space by compressing tables and fragments
        You can reduce disk space by compressing data in tables and table fragments. After compressing data, you can repack the data to consolidate the free space in a table or fragment, and shrink the space for the data to return the free space to the dbspace.
    - 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.
  - InformixHQ Guide
    InformixHQ is a modern web console for visualizing, monitoring, and managing your Informix server instances. It is purpose built for ease-of-use, scaling out, and optimizing DevOps needs. It provides critical performance management capabilities, monitoring how key performance metrics are changing over time and tracking how efficiently Informix is running your workload even when you’ve stepped away from your screen. Its monitoring system feeds directly into a customizable alerting system so you can be immediately alerted via email, Twilio, or PagerDuty whenever an issue occurs on one of your Informix database server instances. InformixHQ is designed to be scalable to efficiently manage and monitor as many Informix database server instances as you need. Moreover, it's a tool that can be shared by the DBAs, the app developers, the ops engineers, and management and accessed from any desktop, laptop, or mobile device. InformixHQ is the centralized hub for graphical monitoring, alerting, and administration of your Informix database servers.
- Backup and Restore Guide
  The Informix® Backup and Restore Guide describes how to use the Informix ON-Bar 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 HCL® Informix® Enterprise Replication Guide describes the concepts of data replication using Informix Enterprise Replication, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.

Estimating table size

You can calculate the approximate sizes (in disk pages) of tables.

For a description of size calculations for indexes, see Estimating index pages.

The disk pages allocated to a table are collectively referred to as a tblspace. The tblspace includes data pages. A separate tblspace includes index pages. If simple large objects (TEXT or BYTE data) are associated with a table that is not stored in an alternative dbspace, pages that hold simple large objects are also included in the tblspace.

The tblspace does not correspond to any fixed region within a dbspace. The data extents and indexes that make up a table can be scattered throughout the dbspace.

The size of a table includes all the pages within the tblspace: data pages and pages that store simple large objects. Blobpages that are stored in a separate blobspace are not included in the tblspace and are not counted as part of the table size.

The following sections describe how to estimate the page count for each type of page within the tblspace.

Tip: If an appropriate sample table exists, or if you can build a sample table of realistic size with simulated data, you do not need to make estimates. You can run oncheck -pt to obtain exact numbers.