Calculating database connections required by the CDC Replication Engine for Informix®

As an administrator, you may find it necessary to calculate how many database connections are needed before installing CDC Replication on either a source or a target database. Calculating the upper bound (both permanent and temporary) database connections will help you plan your environment so that it can accommodate CDC Replication.

This topic includes the formulae and examples to help you calculate the number of connections required by CDC Replication.

Calculating connections required by CDC Replication on a source database

(22 + G)*I + 4*S + L + C

Where:

Note: Enter 0 for any value that does not apply to your deployment of CDC Replication.
  • G = number of Management Console GUI and CHCCLP scripting applications that are connected to your instances of CDC Replication.
  • I = number of CDC Replication instances.
  • S = number of subscriptions in all of your CDC Replication instances.
  • L = number of subscriptions that contain LOB columns.
  • C = number of CDC Replication command line utilities that you plan to use.

Example: How to calculate required connections for a source database

You want to set up CDC Replication in the source environment as follows:

  • 1 instance of Management Console.
  • 2 CDC Replication instances.
  • 3 subscriptions.
  • 1 subscription that uses LOB columns.
  • You do not plan to use any CDC Replication command line utilities.

The number of connections required on the source database will be:

(22+1)*2 + 4*3 + 1 = 59

You should plan for a maximum of 59 database connections before installing CDC Replication on a source database.

Calculating connections required by CDC Replication on a target database

(4+G)*I + 3*S

Where:

  • G = number of Management Console GUI and CHCCLP scripting applications that are connected to your instances of CDC Replication.
  • I = number of CDC Replication instances.
  • S = number of subscriptions in all of your CDC Replication instances.

Example: How to calculate required connections for a target database

You want to set up CDC Replication in the target environment as follows:
  • 1 installed Management Console GUI application.
  • 2 CDC Replication instances.
  • 3 subscriptions.

The number of connections required on the target database will be:

(4 + 1)*2 + 3*3 = 19

You should plan for a maximum of 19 database connections before installing CDC Replication on the target database.