The resync catalog command is used in order to update or resynchronize a recovery catalog from the target database control file. Since sync is done from Target database control file, so you must CONNECT to the recovery catalog as well as to the target database in order to perform the resynchronization.

RMAN> resync catalog;
starting full resync of recovery catalog
full resync complete

When above command is executed, RMAN will first create a snapshot control file. It’ll then compare the contents of the recovery catalog to the contents of the snapshot control file and update the recovery catalog by ADDING the missing information and modifying the changed backup and schema related records.

It means that we will keep PARAMETER control_file_record_keep_time longer than our backup interval, so that the DATA in the control file gets transferred to the recovery catalog before that data is overwritten.

When you issue certain RMAN commands such as the backup command, RMAN AUTOMATICALLY performs a resynchronization.

The resync catalog command is used in order to update or resynchronize a recovery catalog from the target database control file. Since sync is done from Target database control file, so you must connect to the recovery catalog as well as to the target database in order to perform the resynchronization.

RMAN> resync catalog;
starting full resync of recovery catalog
full resync complete

When above command is executed, RMAN will first create a snapshot control file. It’ll then compare the contents of the recovery catalog to the contents of the snapshot control file and update the recovery catalog by adding the missing information and modifying the changed backup and schema related records.

It means that we will keep parameter control_file_record_keep_time longer than our backup interval, so that the data in the control file gets transferred to the recovery catalog before that data is overwritten.

When you issue certain RMAN commands such as the backup command, RMAN automatically performs a resynchronization.