Participant

A participant defines the data (database, table, and columns) on a database server to be replicated. A replicate contains two or more participants. The participant definition includes the following information:

• Database server group (Setting up Database Server Groups)
• Database in which the table resides
• Table name
• Table owner (Table Owner)
• Participant type (Participant Type)
• SELECT statement (Participant Modifier)

You must include the server group, database, table owner, and table name when defining a participant, and enclose the entire participant definition in quotation marks.

>>-"-+---+-+---+-database@server_group:owner.table-"-----------><
     +-P-+ +-O-+
     '-R-' '-I-'
 

You can define participants with the following commands:

• cdr define replicate
• cdr modify replicate
• cdr change replicate
• cdr define template

The P, R, O, and I options are described in the sections below.

Table Owner

The O (owner) option causes permission checks for owner to be applied to the operation (such as insert or update) that is to be replicated and to all actions fired by any triggers. When the O option is omitted, all operations are performed with the privileges of user informix.

On UNIX, if a trigger requires any system-level commands (as specified using the system( ) command in an SPL statement), the system-level commands are executed as the table owner, if the participant includes the O option.

On Windows, if a trigger requires any system-level commands, the system-level commands are executed as a less privileged user because you cannot impersonate another user without having the password, whether or not the participant includes the O option.

Use the I option to disable the table-owner option.

Participant Type

In a primary-target replicate, specify the participant type using the P (primary) and R (receive-only or target) options in the participant definition:

• A primary participant both sends and receives replicate data.
• A target participant only receives data from primary participants.

The replicate can contain multiple primary participants.

In an update-anywhere replicate, do not specify either P or R for the participant. Enterprise Replication defines the participant as primary in an update-anywhere replication system.

For example, in the following definition, replicate Rone is update-anywhere:

cdr define repl -c serv1 -C timestamp -S tran Rone \
"db@serv1:owner.table" "select * from table" \
"db@serv2:owner.table" "select * from table"

In replicate Rtwo, serv2 is the primary and serv1 is receive-only.

cdr define repl -c serv1 -C ignore -S tran Rtwo \
"R db@serv1:owner.table" "select * from table" \
"P db@serv2:owner.table" "select * from table"

For more information, see Primary-Target Replication System.

Participant Modifier

The participant modifier is a restricted SELECT statement. The participant modifier specifies the rows and columns that will be replicated. The participant modifier must be enclosed in quotation marks.

              .-,----------.
              V            |
>>-"SELECT--+-----column---+-+--FROM--table--WHERE_Clause"-----><
            '-*--------------'
 

The following guidelines apply to a SELECT statement that is used as a participant modifier:

• The statement cannot include a join or a subquery.
• The FROM clause of the SELECT statement can reference only a single table.
• The table in the FROM clause must be the table specified by the participant.
• The columns selected must include the primary key.
• The columns selected can include any columns in the table, including those that contain smart large objects and TEXT and BYTE data.
• The statement cannot perform operations on the selected columns.
• The statement can include an optional WHERE clause.

  The WHERE clause of the SELECT statement of the participant modifier can reference an opaque UDT, as long as the UDT is always stored in row. For more information, see Considerations for Replicating Opaque Data Types.

For detailed information about the SELECT statement and WHERE clause, refer to the IBM Informix Guide to SQL: Syntax.