Physical restore parameters

This topic describes the parameters in a restore command.

Restore commands

Commands

• Restore to a specified timestamp

  ALTER SYSTEM RESTORE dest_tenant_name FROM uri UNTIL TIME='timestamp' WITH 'restore_option' [WITH KEY FROM 'backup_key_path' ENCRYPTED BY 'password'] [DESCRIPTION description];
  

• Restore to a specified SCN

  ALTER SYSTEM RESTORE dest_tenant_name FROM uri UNTIL SCN=scn WITH 'restore_option' [WITH KEY FROM 'backup_key_path' ENCRYPTED BY 'password']  [DESCRIPTION description];
  

• Restore to the latest checkpoint

  ALTER SYSTEM RESTORE dest_tenant_name FROM uri WITH 'restore_option' [WITH KEY FROM 'backup_key_path' ENCRYPTED BY 'password'] [DESCRIPTION description];
  

• Cancel an ongoing tenant restore

  ALTER SYSTEM CANCEL RESTORE dest_tenant_name;
  

Parameter explanation

Constraints on timestamp and scn

The timestamp and scn parameters must be greater than or equal to the minimum restore SCN MIN_RESTORE_SCN of data backups in the CDB_OB_BACKUP_SET_FILES view and less than or equal to the maximum archive SCN CHECKPOINT_SCN in the CDB_OB_ARCHIVELOG view. However, the log archive stream may be interrupted, so the restore SCN must avoid the interrupted periods, resulting in a discontinuous restoreable period. The restoreable periods can be segmented.

For example, assume that the backup situation of a user is as follows:

• Two log archives are initiated with round_id of 1 and 2, respectively.

• Three data backups are initiated, and the effective ones are full_backup_set_1, full_backup_set_2, and inc_backup_set_3.

The following figure shows the restoreable periods for physical restore. The right borders of the data backup periods are all at the MIN_RESTORE_SCN, such as scn 300 for the data backup full_backup_set_1; the right borders of the log archive periods are all at the CHECKPOINT_SCN, such as scn 500 for the log archive round 1.

The log archive stream may be interrupted, so the interrupted periods must be excluded when calculating the restore periods, resulting in discontinuous restore periods, namely, {[scn 300, scn 500] \∪ [scn 900, scn 1500]} in the preceding figure.

Performance-related

Command

ALTER SYSTEM SET ha_high_thread_score =10 TENANT = mysql;

Parameter explanation

Commands

Start the restore process

• Restore logs to the specified timestamp, which must be in the YYYY-MM-DD HH24:MI:SS.FF format and include the timestamp parameter. The timestamp parameter must be connected with an = sign. The decimal part (FF) of the timestamp parameter supports 0 to 6 digits to indicate microseconds.

  ALTER SYSTEM RECOVER STANDBY [TENANT tenant_name] UNTIL TIME='timestamp';
  

• Restore logs to the specified SCN, which must be in the =-connected SCN format and include the scn parameter.

  ALTER SYSTEM RECOVER STANDBY [TENANT tenant_name] UNTIL SCN=scn;
  

• Restore logs without an end point, namely, continuously restore archive source logs.

  ALTER SYSTEM RECOVER STANDBY [TENANT tenant_name] UNTIL UNLIMITED;
  

• Cancel the restore process.

  ALTER SYSTEM RECOVER STANDBY TENANT tenant_name CANCEL;
  

Parameters

Active command

Command

ALTER SYSTEM ACTIVATE STANDBY TENANT tenant_name;

Parameter explanation