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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.
Administrator's Guide
The Informix® Administrator's Guide provides the information required to administer HCL Informix.
Disk, memory, and process management
Moving data with external tables
You can use external tables to load and unload database data.
System catalog entries for external tables
You can query system catalog tables to determine the status of external 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.
    - The database server
    - Disk, memory, and process management
      - Virtual processors and threads
        These topics describe virtual processors, explain how threads run within the virtual processors, and explain how the database server uses virtual processors and threads to improve performance.
      - Manage virtual processors
        These topics describe how to set the configuration parameters that affect database server virtual processors, and how to start and stop virtual processors.
      - Shared memory
        These topics describe the content of database server shared memory, the factors that determine the sizes of shared-memory areas, and how data moves into and out of shared memory.
      - Manage shared memory
      - Data storage
        The database server uses physical units of storage to allocate disk space. It stores data in logical units. Unlike the logical units of storage whose size fluctuates, each of the physical units has a fixed or assigned size that is determined by the disk architecture.
      - Manage disk space
        You can use several utilities and tools to manage disk spaces and the data that the database server controls.
      - Moving data with external tables
        You can use external tables to load and unload database data.
        External tables
        An external table is a data file that is not managed by the Informix® database server. The definition of the external table includes data-formatting type, external data description fields, and global parameters.
        Defining external tables
        To define an external table, you use SQL statements to describe the data file, define the table, and then specify the data to load or unload.
        Map columns to other columns
        Load data from and unload to a named pipe
        You can use a named pipe, also called a first-in-first-out (FIFO) data file, to load from and unload to a nonstandard device, such as a tape drive.
        Monitor the load or unload operations
        You can monitor the status of an external table load or unload operation.
        External tables in high-availability cluster environments
        You use external tables on secondary servers in much the same way they are used on the primary server.
        System catalog entries for external tables
        You can query system catalog tables to determine the status of external tables.
        Performance considerations when using external tables
        Use external tables when you want to manipulate data in an ASCII file using SQL commands, or when loading data from an external data file to a RAW database table.
        Manage errors from external table load and unload operations
        You can manage errors that occur during external table load and unload operations.
      - Storage space encryption
        You can encrypt storage spaces (dbspaces, blobspaces and smart blobspaces) with Informix Dynamic Server. The data in encrypted storage spaces is unintelligible without the encryption key. Encrypting storage spaces is an effective way to protect sensitive information that is stored on disk.
    - Logging and log administration
    - Fault tolerance
    - High availability and scalability
      A successful production environment requires database systems that are always available, with minimal if any planned outages, and that can be scaled quickly and easily as business requirements change.
    - Distributed data
    - Overview of automatic monitoring and corrective actions
      You can use the SQL administration API, the Scheduler, and drill-down queries to manage automatic maintenance, monitoring, and administrative tasks.
  - 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.
  - 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.

System catalog entries for external tables

You can query system catalog tables to determine the status of external tables.

HCL Informix® updates the sysexternal and sysextdfiles system catalog tables each time an external table is created. The sysextcols system catalog table is updated when the external format type (fmttype) FIXED is specified.

Table 1. System catalog tables that describe external table files
Table name	Description
sysexternal	Stores name and attributes of each external table file
sysextdfiles	Stores file-path and directory of each external table file
sysextcols	Stores attributes of each column in FIXED-type external tables

See the Informix® Guide to SQL: Reference for more information.

A row is inserted into the systables system catalog when an external table is created; however, the nrows (number of rows) and the npused (number of data pages used) columns might not accurately reflect the number of rows and the number of data pages used by the external table unless the NUMROWS clause was specified when the external table was created.

When an external table is created without specifying a value for the NUMROWS clause, Informix® is unable to determine the number of rows in the external table because the data exists outside the database in data files. Informix® updates the nrows column in the systables system catalog by inserting a large value (MAXINT - 1), and computes the number of data pages used based on the nrows value. The values stored in npused and nrows are later used by the optimizer to determine the most efficient execution plan. While the NUMROWS clause is not required to be specified precisely, the more accurately it is specified, the more accurate the values for nrows and npused are.