Setting advanced connection properties

In the Advanced tab, you can configure CDC parameters, set internal parameters, and view a summary of your settings.

• Capture DDL events: When this option is selected, the following actions occur:
  • Operational artifacts are created (by Replicate) in the database when the task starts. In order to capture DDL events, Qlik Replicate creates various artifacts in the Google Cloud SQL for PostgreSQL database when the task starts. You can later remove these artifacts as described in Removing Replicate artifacts from the Google Cloud SQL for PostgreSQL database.
  • Streamed DDL events are captured.
• Create DDL artifacts in schema: The schema in which the operational DDL database artifacts will be created. The default value is "Public".

• WAL heartbeat: An Apply Changes task that is running but not capturing changes (due to source table inactivity) will continue to occupy the LSN position in its replication slot, thereby preventing truncation of the WAL. Since the WAL is a server-wide resource used by all Google Cloud SQL for PostgreSQL processes, it may grow extremely large if no changes are captured for an extended period.

  To prevent this from happening, enable the "WAL heartbeat" option. When this option is enabled, the Google Cloud SQL for PostgreSQL source endpoint mimics task activity by periodically committing pseudo transactions (i.e. "Heartbeats") to the heartbeat table, thereby advancing the task slot’s LSN position.

  • Schema for heartbeat artifacts: The schema in which the WAL heartbeat table (attrep_wal_heartbeat) will be created. The default value is "public".
  • Heartbeat frequency (minutes): The frequency with which to commit transactions to the heartbeat table.

• Map BOOLEAN to Replicate BOOLEAN data type (instead of STRING (5)): Select this option if you want BOOLEAN columns to be mapped to the Replicate BOOLEAN data type instead of STRING (5).

• Retention period in minutes

  Information noteThis option is only relevant when using the Tables are already loaded. Start processing changes from advanced run option to restart a task.

  The number of minutes to retain processed transactions in the logical replication slot before they are purged. The longer the retention period, the older the transactions that will be retained. If you specify a short retention period, transactions that occurred a few days before the task stopped might not be available when you restart the task.

  Tip note As a precaution, the default value is one minute as this does not require extra storage space. However, best practice is to set a retention period that will allow Replicate to process captured changes as far back as possible, while taking into account the available storage space.

  The length of the retention period should be determined by the following factors:

  • When you might need to start processing changes from. For example, if you need to process changes up to three days before the task stopped, set the value to at least 4320.

  • The amount of available storage space in the PostgreSQL database. A longer retention period requires additional storage for the logical replication slot and should therefore be approved by the DBA.

Internal parameters

Internal parameters are parameters that are not exposed in the UI. You should only use them if instructed by Qlik Support.

To add internal Qlik Replicate parameters:

1. Click the Internal Parameters link.

   The Internal Parameters dialog box opens.

2. In the edit box, type the name of the parameter you need to add and then click it.
3. The parameter is added to the table below the search box with its default value.
4. Change the default value as required.
5. To reset the parameter value to its default, click the "Restore default value" icon at the end of the row.

More options

These options are not exposed in the UI as they are only relevant to specific versions or environments. Consequently, do not set these options unless explicitly instructed to do so by Qlik Support or product documentation.

To set an option, simply copy the option into the Add feature name field and click Add. Then set the value or enable the option according to the instructions you received.

Settings summary

You can view a summary of your settings by clicking the Setting Summary link. This is useful if you need to send a summary of your settings to Qlik Support.