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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.
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.
Planning a fragmentation strategy
You can decide on a fragmentation goal for your database and devise a strategy to meet that goal.
Examining your data and queries
To determine a fragmentation strategy, you must gather information about the table that you might fragment. You must also know how the data in the table is used.

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.
    - 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.
      - Planning a fragmentation strategy
        You can decide on a fragmentation goal for your database and devise a strategy to meet that goal.
        Fragmentation goals
        You can analyze your application and workload to identify fragmentation goals and to determine the balance to strike among fragmentation goals.
        Examining your data and queries
        To determine a fragmentation strategy, you must gather information about the table that you might fragment. You must also know how the data in the table is used.
        Considering physical fragmentation factors
        When you fragment a table, the physical placement issues that pertain to tables apply to individual table fragments. Because each fragment resides in its own dbspace on a disk, you must address these issues separately for the fragments on each disk.
      - Distribution schemes
        After you decide whether to fragment table rows, index keys, or both, and you decide how the rows and keys should be distributed over fragments, you can decide on a scheme to implement this distribution. Informix® supports random distribution among fragments and value-based distribution among fragments.
      - Strategy for fragmenting indexes
        When you fragment a table, the indexes that are associated with that table are fragmented implicitly, according to the distribution scheme that you use, except for the round-robin fragmentation scheme when automatic location is enabled. Indexes on tables that use the round-robin distribution scheme are not fragmented when the AUTOLOCATE configuration parameter or environment option is set to a positive integer. You can use the FRAGMENT BY clause of the CREATE INDEX statement to fragment the index on any table.
      - Strategy for fragmenting temporary tables
        You can fragment an explicit temporary table across dbspaces that reside on different disks.
      - Distribution schemes that eliminate fragments
        Fragment elimination is a database server feature that reduces the number of fragments involved in a database operation. This capability can improve performance significantly and reduce contention for the disks on which fragments reside.
      - Improve the performance of operations that attach and detach fragments
        When you use ALTER FRAGMENT ATTACH and DETACH statements to add or remove a large amount of data in a very large table, you can take steps to improve the performance of the ATTACH and DETACH operations.
      - Monitoring Fragment Use
        Once you determine a fragmentation strategy, you can monitor 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.

Examining your data and queries

To determine a fragmentation strategy, you must gather information about the table that you might fragment. You must also know how the data in the table is used.

Procedure

To gather information about your table:

Identify the queries that are critical to performance to determine if the queries are online transaction processing (OLTP) or decision-support system (DSS) queries.
Use the SET EXPLAIN statement to determine how the data is being accessed.
For information about the output of the SET EXPLAIN statement, see Report that shows the query plan chosen by the optimizer. To determine how the data is accessed, you can sometimes simply review the SELECT statements along with the table schema.
Determine what portion of the data each query examines.
For example, if certain rows in the table are read most of the time, you can isolate them in a small fragment to reduce I/O contention for other fragments.
Determine which statements create temporary files.
Decision-support queries typically create and access large temporary files, and placement of temporary dbspaces can be critical to performance.
If particular tables are always joined together in a decision-support query, spread fragments for these tables across different disks.
Examine the columns in the table to determine which fragmentation scheme would keep each scan thread equally busy for the decision-support queries.
To see how the column values are distributed, create a distribution on the column with the UPDATE STATISTICS statement and examine the distribution with dbschema.
```
dbschema -d database -hd table
```