Replication Scheme

A replication scheme is the set of replication definitions for a database. These definitions identify the following:

• Consistent Distributed Data Sets (CDDSs)
• Data propagation paths
• CDDS target types

Your replication definitions are codified when you configure your Ingres Replicator installation.

Replication Scheme Planning Worksheets

You need an accurate representation of your replication scheme to accurately configure Ingres Replicator.

The planning worksheets help you to represent your replication scheme. When you are ready to start configuring Ingres Replicator, these worksheets will already contain most of the information you need to select appropriate options in configuration screens.

We recommend that you fill out the following worksheets:

• Database Worksheet, which contains a list of the databases in the replicated environment.
• CDDS Definition Worksheet, which contains information about the CDDSs that you need when configuring Ingres Replicator.
• Table Worksheet (optional), which contains table and column information. You can use this worksheet if you need to list table information or if you are planning vertical or horizontal partitioning.

The following table is a checklist of the tasks described in this section:

This chapter uses a sample replication scheme, which is also used in the chapters "Configuring Replication Using Visual DBA" and "Configuring Replication Using Replicator Manager." For examples of other replication schemes and their worksheets, see Replication Scheme Examples.

Database Worksheet

The Database Worksheet defines the distributed environment for all CDDSs in your replication scheme. The following table describes the guidelines for filling in the Database Worksheet.

The following is an example of a Database Worksheet.

The following figure illustrates a completed Database Worksheet.

Identifying the CDDS

Carefully examine the way data is used among the different databases in your system to determine your CDDSs. Remember that CDDSs are indivisible and mutually exclusive; you cannot split the information in a CDDS so that it goes to different targets, and you cannot contain the same data in more than one CDDS. If you later decide to divide a CDDS, you must reconfigure Ingres Replicator.

For the definition of a CDDS and examples, see Consistent Distributed Data Set (CDDS).

The CDDS Worksheet is divided into the following sections:

• CDDS summary
• CDDS diagram
• Database information
• Propagation paths

The CDDS Worksheet and a sample completed CDDS Worksheet are at the end of this section.

CDDS Summary Information

The CDDS summary information defines the scope of the CDDS and how it handles collisions and errors. The following table describes how to fill in the CDDS summary section of the CDDS Worksheet.

CDDS Diagram

Use the CDDS Diagram to create a visual representation of your replication scheme. This overview of your replication scheme gives you an instant understanding of your plan and can expose errors or omissions in your plan.

The CDDS Diagram consists of the following elements:

• Shapes (databases)

  Label each database with its name, number, and target type.

• Arrows (propagation paths)

  Draw a line for every path, and an arrow pointing at the target. Read-only targets have only incoming arrows, while full peer targets have incoming and outgoing arrows. Label each arrow with the number of the Replicator Server that is propagating to that target.

Database Information

The database information describes the behavior of the database within the CDDS. The following table describes how to fill in the database information section of the CDDS Worksheet.

Propagation Paths

Based on the CDDS diagram, fill in propagation paths. For an explanation and examples of data propagation paths, see Data Propagation Paths in the CDDS.

CDDS Worksheet

Define worksheet entries so that an update that occurs on any of the full peer databases within the CDDS is propagated to all of the other databases that participate in the CDDS. For example, if you have two databases in the CDDS that act as full peers, each of them must be an originator in one propagation path and a target in another propagation path. The following table describes how to fill in the propagation path section of the CDDS Worksheet:

The following forms provide examples of CDDS Worksheets.

The following figure illustrates a completed CDDS Worksheet.

Table Worksheet

The Table Worksheet allows you to document your replicated table and column information in detail.

You must complete this worksheet if you are including vertical or horizontal partitioning in your CDDS. Vertical partitioning refers to replicating a subset of a table's columns. Horizontal partitioning refers to replicating a subset of a table's rows based on values in a particular column.

For information on how to use partitioning in your replication scheme, see Consistent Distributed Data Set (CDDS). For information on horizontal partitioning, see How You Set Up Horizontal Partitioning.

The following figure shows an example of a Table Worksheet.

The following figure illustrates a completed Table Worksheet.