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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.
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.
The query plan
The query optimizer evaluates the different ways in which a query might be performed and determines the best way to select the requested data. During this evaluation, the optimizer formulates a query plan to fetch the data rows that are required to process a query.
XML query plans in Data Studio
Data Studio consists of a set of tools to use for administration, data modeling, and building queries from data that comes from data servers. The EXPLAIN_SQL routine prepares a query and returns a query plan in XML. The Data Studio Administration Edition can use the EXPLAIN_SQL routine to obtain a query plan in XML format, interpret the XML, and render the plan visually.

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.
    - 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.
      - The query plan
        The query optimizer evaluates the different ways in which a query might be performed and determines the best way to select the requested data. During this evaluation, the optimizer formulates a query plan to fetch the data rows that are required to process a query.
        The access plan
        The way that the optimizer chooses to read a table is called an access plan. The simplest method to access a table is to read it sequentially, which is called a table scan. The optimizer chooses a table scan when most of the table must be read or the table does not have an index that is useful for the query.
        The join plan
        When a query contains more than one table, Informix® joins the tables using filters in the query. The way that the optimizer chooses to join the tables is the join plan.
        Example of query-plan execution
        This topic contains an example of a query with a SELECT statement that calls for a three-way join and describes one possible query plan.
        Query plans that include an index self-join path
        An index self-join is a type of index scan that you can think of as a union of many small index scans, each one with a single unique combination of lead-key columns and filters on non-lead-key columns.
        Query plan evaluation
        The optimizer considers all query plans by analyzing factors such as disk I/O and CPU costs.
        Report that shows the query plan chosen by the optimizer
        Any user who runs a query can use the SET EXPLAIN statement or the EXPLAIN directive to display the query plan that the optimizer chooses.
        Sample query plan reports
        The topics in this section describe sample query plans that you might want to display when analyzing the performance of different kinds of queries.
        XML query plans in Data Studio
        Data Studio consists of a set of tools to use for administration, data modeling, and building queries from data that comes from data servers. The EXPLAIN_SQL routine prepares a query and returns a query plan in XML. The Data Studio Administration Edition can use the EXPLAIN_SQL routine to obtain a query plan in XML format, interpret the XML, and render the plan visually.
      - Factors that affect the query plan
        When the optimizer determines the query plan, it assigns a cost to each possible plan and then chooses the plan with the lowest cost. The optimizer analyzes several factors to determine the cost of each query plan.
      - Time costs of a query
        You can adjust a few, but not all, of the response-time effects of actions that the database server performs when processing a query.
      - Optimization when SQL is within an SPL routine
        If an SPL routine contains SQL statements, the database server optimizes and executes the SQL within the SPL routine.
      - Trigger execution
        A trigger is a database object that automatically executes one or more SQL statements (the triggered action) when a specified data manipulation language operation (the triggering event) occurs. You can define one or more triggers on a table to execute after a SELECT, INSERT, UPDATE or DELETE triggering event.
    - 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.

XML query plans in Data Studio

Data Studio consists of a set of tools to use for administration, data modeling, and building queries from data that comes from data servers. The EXPLAIN_SQL routine prepares a query and returns a query plan in XML. The Data Studio Administration Edition can use the EXPLAIN_SQL routine to obtain a query plan in XML format, interpret the XML, and render the plan visually.

If you plan to use Data Studio to obtain Visual Explain output, you must create and specify a default sbspace name for the SBSPACENAME configuration parameter in your onconfig file. The EXPLAIN_SQL routine creates BLOBs in this sbspace.

For information about using Data Studio, see Data Studio documentation.