Defining Participants

Home | Previous Page | Next Page Setting Up and Managing Enterprise Replication > Defining Replication Servers, Replicates, Participants, and Replicate Sets > Defining Replicates >

Defining Participants

You must define participants for each server involved in the replicate in the replicate definition using the cdr define replicate command.

Important:

You cannot start and stop replicates that have no participants.

Each participant definition includes the following information:

Database server group name
Database in which the table to be replicated resides
Table name
Table owner
See Table Owner.
SELECT statement and optional WHERE clause
See Participant Modifier.

If you use a SELECT * FROM table_name statement, the tables must be identical on all database servers defined for the replicate.

Important:

Do not create more than one participant definition for each row and column to replicate. If the participant is the same, Enterprise Replication attempts to insert or update duplicate values during replication. For example, if one participant modifier includes WHERE x < 50 and another includes WHERE x < 100, Enterprise Replication sends the data for when x is between 50 and 100 twice.

In addition, for a primary-target replication system, you can specify the participant type as either primary or target (receive-only). If you do not specify the participant type, Enterprise Replication defines the participant as update-anywhere, by default. For more information, see Primary-Target Replication System and Participant Type.

For example, in the following participant definition, the P indicates that in this replicate, hawaii is a primary server:

"P db1@g_hawaii:informix.mfct" "select * from mfct" \

If any data in the selected columns changes, that changed data is sent to the secondary servers.

In the following example, the R indicates that in this replicate, maui is a secondary server:

"R db2@g_maui:informix.mfct" "select * from mfct"

The specified table and columns receive information sent from the primary server. Changes to those columns on maui are not replicated.

Important:

The R in the participant definition indicates that the table is receive-only mode, not that the table is in read-only mode.

If you do not specify the participant type, Enterprise Replication defines the participant as update-anywhere by default. For example:

"db1@g_hawaii:informix.mfct" "select * from mfct" \
"db2@g_maui:informix.mfct" "select * from mfct"

For more information, see Participant.

Defining Replicates on Table Hierarchies

When you define replicates on inherited table hierarchies, use the following guidelines to replicate operations:

For both the parent and child tables, define a replicate on each table.
For only the parent table (not the child table), define a replicate on the parent table only.
For only the child table (not the parent table), define a replicate on the child table only.