Overview

BCT

An abbreviation for Block Change Tracking, it is a method to back up only the changed blocks when performing an incremental backup after a full backup with tbrmgr.

By reading the redo buffer, whenever a block is modified, the change history is recorded as a bitmap in the BCT file.

During incremental backup, this bitmap is referenced to quickly back up only the changed blocks instead of all blocks.

Related Parameters

• Set in $TB_HOME/config/$TB_SID.tip
• Set the BLOCK_CHANGE_TRACKING parameter to the absolute path of the BCT file
• ex) BLOCK_CHANGE_TRACKING=/home/t/tbdata/tibero.bct

Related Commands

• Enable BCT feature: ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING;
• Disable BCT feature: ALTER SYSTEM DISABLE BLOCK CHANGE TRACKING;

Method

Test Scenario

Modify $TB_SID.tip

...

BLOCK_CHANGE_TRACKING=/home/tibero/tibero7/block/tibero.bct

Enable BCT and Verify Activation

• Enable BCT with the command ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING;
• If the ENABLED column in _vt_bct is 1, BCT is enabled; if 0, it is disabled

$ tbsql sys/tibero

tbSQL 7

TmaxTibero Corporation Copyright (c) 2020-. All rights reserved.

Connected to Tibero.

SQL> select * from _vt_bct;

   ENABLED     SET_ID CUR_SET_ID    REQ_TSN
---------- ---------- ---------- ----------
         0          0          0     170649
         0          1          0     170597

2 rows selected.

SQL> ALTER SYSTEM ENABLE BLOCK CHANGE TRACKING;

System altered.


SQL> select * from _vt_bct;

   ENABLED     SET_ID CUR_SET_ID    REQ_TSN
---------- ---------- ---------- ----------
         1          0          0     172019
         1          1          0     170597

2 rows selected.

Perform Full Backup

$ tbrmgr backup -o /home/tibero/tibero7/block/backup

==============================================================================
=   Recovery Manager(RMGR) starts                                            =
=                                                                            =
=   TmaxTibero Corporation Copyright (c) 2020-. All rights reserved.         =
==============================================================================
archive log check succeeded
RMGR '-o' option used
: backing up to /home/tibero/tibero7/block/backup

==============================================================================
   RMGR - Backup (FULL)
==============================================================================
Initializing the backup progress, it may take few minutes...

BACKUP  (set_id:  4, ts_id:  0, df_id:  0)
100.0% |===============================|   13568/13568   blks    0.00s
Synchronizing...
BACKUP  (set_id:  4, ts_id:  1, df_id:  1)
100.0% |===============================|   13056/13056   blks    0.00s
Synchronizing...
BACKUP  (set_id:  4, ts_id:  3, df_id:  2)
100.0% |===============================|    1280/1280    blks    0.00s
Synchronizing...
BACKUP  (set_id:  4, ts_id:  4, df_id:  3)
100.0% |===============================|    2560/2560    blks    0.00s
Synchronizing...

Switching an online logfile...

Backing up the control file...
Control file backup succeeded

Database backup succeeded

RMGR backup ends

Perform Incremental Backup

$ tbrmgr backup -i -o /home/tibero/tibero7/block/backup2

==============================================================================
=   Recovery Manager(RMGR) starts                                            =
=                                                                            =
=   TmaxTibero Corporation Copyright (c) 2020-. All rights reserved.         =
==============================================================================
archive log check succeeded
RMGR '-o' option used
: backing up to /home/tibero/tibero7/block/backup2

==============================================================================
   RMGR - Backup (INCREMENTAL)
==============================================================================
Initializing the backup progress, it may take few minutes...

BACKUP  (set_id:  3, ts_id:  0, df_id:  0)
100.0% |===============================|     269/269     blks    0.00s
Synchronizing...
BACKUP  (set_id:  3, ts_id:  1, df_id:  1)
100.0% |===============================|    1056/1056    blks    0.00s
Synchronizing...
BACKUP  (set_id:  3, ts_id:  3, df_id:  2)
100.0% |===============================|       2/2       blks    0.00s
Synchronizing...
BACKUP  (set_id:  3, ts_id:  4, df_id:  3)
100.0% |===============================|     916/916     blks    0.00s
Synchronizing...

Switching an online logfile...

Backing up the control file...
Control file backup succeeded

Database backup succeeded

RMGR backup ends