Home
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.
Indexes and index performance considerations
Informix® provides several types of indexes. Some performance issues are associated with indexes.
Improving performance for index builds
You can improve performance for index builds by adjusting the PDQ priority and by allocating enough memory and temporary space for the entire index.
Estimating temporary space for index builds
You can estimate the number of bytes of temporary space needed for an entire index build.

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.
    - Boosted Partition Free Space Caches (PFSC)
    - Indexes and index performance considerations
      Informix® provides several types of indexes. Some performance issues are associated with indexes.
      - Types of indexes
        Informix® uses B-tree indexes, R-tree indexes, functional indexes, and indexes that DataBlade® modules provide for user-defined data. The server also uses forest of trees (FOT) indexes, which are alternatives to B-tree indexes.
      - Estimating index pages
        The index pages associated with a table can add significantly to the size of a dbspace.
      - Managing indexes
        An index on the appropriate column can save thousands, tens of thousands, or in extreme cases, even millions of disk operations during a query. However, indexes entail costs.
      - Improve query performance with a forest of trees index
        A forest of trees index is an alternate indexing method that alleviates the performance bottlenecks and root node contention that can occur when many concurrent users access a traditional B-tree index.
      - Creating and dropping an index in an online environment
        You can use the CREATE INDEX ONLINE and DROP INDEX ONLINE statements to create and drop an index in an online environment, when the database and its associated tables are continuously available.
      - Improving performance for index builds
        You can improve performance for index builds by adjusting the PDQ priority and by allocating enough memory and temporary space for the entire index.
        Estimating memory needed for sorting
        To calculate the amount of virtual shared memory that the database server might need for sorting, estimate the maximum number of sorts that might occur concurrently and multiply that number by the average number of rows and the average row size.
        Estimating temporary space for index builds
        You can estimate the number of bytes of temporary space needed for an entire index build.
      - Storing multiple index fragments in a single dbspace
        You can store multiple fragments of the same index in a single dbspace, 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 index fragments in a single dbspace simplifies the management of dbspaces.
      - Improving performance for index checks
        The oncheck utility provides better concurrency for tables that use row locking. When a table uses page locking, oncheck places a shared lock on the table when it performs index checks. Shared locks do not allow other users to perform updates, inserts, or deletes on the table while oncheck checks or prints the index information.
      - Indexes on user-defined data types
        You can define your own data types and the functions that operate on these data types. You can define indexes on some kinds of user-defined data types.
    - 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 temporary space for index builds

You can estimate the number of bytes of temporary space needed for an entire index build.

About this task

To estimate the amount of temporary space needed for an index build, perform the following steps:

Procedure

Add the total widths of the indexed columns or returned values from user-defined functions. This value is referred to as colsize.
Estimate the size of a typical item to sort with one of the following formulas, depending on whether the index is attached or not:
1. For a nonfragmented table and a fragmented table with an index created without an explicit fragmentation strategy, use the following formula:
```
sizeof_sort_item = keysize + 4
```
2. For fragmented tables with the index explicitly fragmented, use the following formula:
```
sizeof_sort_item = 
```
```
keysize + 8
```
Estimate the number of bytes needed to sort with the following formula:
```
temp_bytes = 2 * (rows *
sizeof_sort_item)
```
This formula uses the factor 2 because everything is stored twice when intermediate sort runs use temporary space. Intermediate sort runs occur when not enough memory exists to perform the entire sort in memory.
The value for rows is the total number of rows that you expect to be in the table.