Welcome
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
Enterprise Replication
The describes the concepts of data replication using HCL 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.
Out-of-Row Data

HCL Informix® V15.0.0 documentation
Welcome to the documentation for HCL Informix® 15.0.0 and related client tools and products.
Product overview
HCL Informix® is a fast and scalable database server that manages traditional relational, object-relational, and dimensional databases. Its small footprint and self-managing capabilities are suited to embedded data-management solutions.
Installing
These topics describe how to install HCL Informix® database servers, client products, and modules.
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 HCL® Informix® Backup and Restore Guide describes how to use the HCL Informix 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 describes the concepts of data replication using HCL Informix® Enterprise Replication, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.
  - About Enterprise Replication
    HCL 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 interacts with the database server and the other requirements of . Many aspects of the Informix® database server can affect how you deploy .
    - 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
        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
Migrating and upgrading
You can upgrade to the 15.0.0 release of HCL Informix® or migrate from other database servers to Informix. Upgrading is an in-place migration method that uses your existing hardware and operating system software. Some changes to the Informix database server can affect upgrading from a previous release.
Client APIs and tools
You can use the HCL Informix® implementation of client APIs to develop applications for Informix database servers.
Embedding Informix®
When you embed HCL Informix®, you can use enterprise-class high-availability and high performance with embeddability features such as easy programmability, a small disk and memory footprint, and silent deployment.
Extending Informix®
Beyond standard relational database objects, HCL Informix® can be extended to handle specialized data types, access methods, routines, and other objects. Informix includes many built-in extensions that are fully integrated in the database server. Informix also provides modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for Informix.
Data warehousing
In addition to designing and implementing Informix® dimensional databases, you can use tools to create data warehouse applications and optimize your data warehouse queries.
Designing databases
The first step in creating a relational database is to construct a data model, which is a precise, complete definition of the data you want to store. After you prepare your data model, you must implement it as a database and tables. To implement your data model, you first select a data type for each column and then you create a database and tables and populate the tables with data. You can also implement fragmentation strategies and control access to your data.
JSON compatibility
You can use the popular JSON-oriented query language created by MongoDB to interact with data stored in HCL Informix®.
Security
You can secure your Informix® database server and the data that is stored in your Informix databases. You can encrypt data, secure connections, control user privileges and access, and audit data security.
SQL programming
You can use the HCL Informix® implementation of the SQL language to develop applications for Informix database servers.
Troubleshooting HCL Informix®
Several troubleshooting techniques, tools, and resources are available for resolving problems that you encounter in your HCL Informix® database server environment.

Out-of-Row Data

collects out-of-row data for transmission after the user transaction has committed. Due to activity on the replicated row, the data might not exist at the time collects it for replication. In such cases, normally applies a NULL on the target system, unless the data is a smart large object. Therefore, you should avoid placing a NOT NULL constraint on any replicated column that includes out-of-row data.

If a column has smart large objects and the smart large object data does not exist when Enterprise Replication collects it for replication, then Enterprise Replication creates smart large objects with no data and zero size.