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Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
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.
Planning and designing for Enterprise Replication
Before you set up your replication system, plan how to include Enterprise Replication into your database server environment, design your database schema by following Enterprise Replication requirements, and then design your replication system between database servers.
Schema design for Enterprise Replication
When you design the database and tables for replication, you must follow the requirements and restrictions for Enterprise Replication.
Unbuffered Logging

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.
- 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.
  - About Enterprise Replication
    Informix® Enterprise Replication generates and manages multiple copies of data at one or more sites, which allows an enterprise to share corporate data throughout its organization.
  - Planning and designing for Enterprise Replication
    Before you set up your replication system, plan how to include Enterprise Replication into your database server environment, design your database schema by following Enterprise Replication requirements, and then design your replication system between database servers.
    - Plan for Enterprise Replication
      Before you design a replication system, you must understand how Enterprise Replication interacts with the database server and the other requirements of Enterprise Replication. Many aspects of the Informix® database server can affect how you deploy Enterprise Replication.
    - Schema design for Enterprise Replication
      When you design the database and tables for replication, you must follow the requirements and restrictions for Enterprise Replication.
      - Unbuffered Logging
      - Table Types
        Enterprise Replication has restrictions on the types of tables that can participate in replication.
      - Label-based access control
        You cannot apply label-based access control (LBAC) to a table participating in Enterprise Replication. Nor can you define an Enterprise Replication replicate on a table that is protected by LBAC.
      - Out-of-Row Data
      - Shadow columns
        Shadow columns are hidden columns on replicated tables that contain values that are supplied by the database server. The database server uses shadow columns to perform internal operations.
      - Unique key for replication
        All tables that are replicated must have a replication key that is composed of one or more columns that uniquely identifies each row. The replication key must be the same on all servers that participate in the replicate. Typically, the replication key is a primary key constraint.
      - Cascading Deletes
        If a table includes a cascading delete, when a parent row is deleted, the children are also deleted. If both the parent and child tables participate in replication, the deletes for both the parent and child are replicated to the target servers.
      - Triggers
        A trigger is a database object that automatically sets off a specified set of SQL statements when a specified event occurs.
      - Constraint and replication
        When you use constraints, ensure that the constraints you add at the target server are not more restrictive than the constraints at the source server. Discrepancies between constraints at the source and target servers can cause some rows to fail to be replicated.
      - Sequence Objects
      - The NLSCASE database property
        Enterprise Replication supports both case-sensitive databases and NLSCASE INSENSITIVE databases. (Databases created with the NLSCASE INSENSITIVE option ignore letter case in operations on NCHAR and NVARCHAR strings, and on strings of other character data types that are cast explicitly or implicitly to NCHAR or NVARCHAR data types.)
      - Replicating Table Hierarchies
        To replicate tables that form a hierarchy, you must define a separate replicate for each table.
      - Replication and data types
        Enterprise Replication supports built-in data types and user-defined data types, including row types and collection types.
    - Replication system design
      When you design a replication system, you make three main decisions: how the information flows between servers, how to resolve conflicts between replicated data, and the topology of the network of servers.
  - Setting up and managing Enterprise Replication
    After you design your replication system, you define it and start replication.
  - Push data feature
  - Loopback replication
  - Appendixes

Unbuffered Logging

Databases on all server instances involved in replication must be created with logging.

Enterprise Replication evaluates the logical log for transactions that modify tables defined for replication. If a table defined for replication resides in a database that uses buffered logging, the transactions are not immediately written to the logical log, but are instead buffered and then written to the logical log in a block of logical records. When this occurs, Informix® Enterprise Replication evaluates the buffer of logical-log records all at once. Buffered logging can require more time to flush the logs to disk. When you define a table for replication in a database created with unbuffered logging, Enterprise Replication can evaluate the transactions as they are produced.

Unlogged changes to a table, such as when data is added by a light append, can be replicated to other tables.

To create a database with unbuffered logging, use:

CREATE DATABASE db_name WITH LOG

To minimize impact on the system, Informix® Enterprise Replication uses buffered logging whenever possible, even if the database is defined as unbuffered. For more information, see the section on CREATE DATABASE in the Informix® Database Design and Implementation Guide.