2.1.5 Restoring an Incremental Backup

Restoring an incremental backup may require additional setup steps depending upon the host on which the incremental backup is to be restored:

•	BART Host. If an incremental backup is to be restored onto the same host where BART has been installed, the restore process is outlined in Section 2.1.5.1.

•	Remote Host. If an incremental backup is to be restored onto a remote host where BART has not been installed, the restore process still follows the steps outlined in Section 2.1.5.1, but in addition, the requirements in Section 2.1.5.2 must be met.

The bart program must be available on the remote host because the RESTORE subcommand invocation for an incremental backup results in the execution of the bart program on the remote host to restore the modified blocks to their proper location within the restore directory.

The following section describes the general incremental backup restore process.

2.1.5.1 General Restore Process for an Incremental Backup

Specify a backup identifier or name, and include the -i option when invoking the RESTORE subcommand to restore an incremental backup. All RESTORE options are used in the same manner as when restoring a full backup.

First, all files from the full backup from the beginning of the backup chain are restored.

For each incremental backup, the CBM file is used to identify and restore blocks from the incremental backup.

If there are new relations or databases identified in the CBM file, then relevant relation files are copied. If consolidated block map information is found indicating the drop of a relation or a database, then the relevant files are removed from the restore directory. Similarly if there is any indication of a table truncation, then the related files are truncated.

See Section 3.4.8 for information about using the RESTORE subcommand for restoring an incremental backup. Also note the usage of the -w option of the RESTORE subcommand to specify a multiple number of parallel worker processes to stream the modified blocks to the restore host.

2.1.5.2 Restoring an Incremental Backup on a Remote Host

If an incremental backup is to be restored on a remote host on which BART has not been installed, you must perform the following steps.

Step 1: Install BART on the remote host to which an incremental backup is to be restored. See EDB Postgres Backup and Recovery Installation and Upgrade Guide for instructions on how to install BART.

Note: No editing is needed in the bart.cfg file installed on the remote host.

Step 2: Determine the Linux operating system user account on the remote host to be used as the remote user. This user is specified by the remote_host parameter in the BART configuration file or by the -r option when using the RESTORE subcommand to restore the incremental backup. The remote user must be the owner of the directory where the incremental backup is to be restored on the remote host. By default, the user account is enterprisedb for Advanced Server or postgres for PostgreSQL.

Step 3: Ensure a password-less SSH/SCP connection is established from the BART user on the BART host to the remote user on the remote host. See the configuration section of the EDB Postgres Backup and Recovery Installation and Upgrade Guide for details.