MAJOR and MINOR

Purpose

This statement is used to initiate a major freeze (storage layer major compaction) or minor freeze (storage layer minor compaction) for the system tenant. Manual major compactions can be performed at the tenant, table, or partition level. Manual minor compactions can be performed at the tenant, zone, server, log stream, or partition level.

Syntax

ALTER SYSTEM merge_action;

merge_action:
      MAJOR FREEZE [tenant_list]
    | MAJOR FREEZE TENANT [=] tenant_name {TABLE_ID = table_id | TABLET_ID = tablet_id}
    | MINOR FREEZE [tenant_list | server_list | zone_list]
    | MINOR FREEZE TENANT [=] tenant_name [LS [=] ls_id] [TABLET_ID = tablet_id] 
    | {SUSPEND | RESUME} MERGE [tenant_list]
    | CLEAR MERGE ERROR [tenant_list]

tenant_list:
    TENANT [=]  { all | all_user | all_meta } | tenant_name [, tenant_name ...]

server_list:
    SERVER [=] ('ip:port' [, 'ip:port'...])

zone_list:
    ZONE [=] ('zone_name' [, 'zone_name' ...])

Parameters

Considerations

Partitions and tablets are one-to-one. When you initiate a partition-level major freeze (storage layer major compaction), note the following:

• You cannot initiate a partition-level major freeze (storage layer major compaction) if the corresponding partition is being processed by a tenant-level major freeze (storage layer major compaction).
• You cannot initiate a partition-level major freeze (storage layer major compaction) if the corresponding partition is being processed by an adaptive scheduling major freeze (storage layer major compaction).
• You cannot initiate a partition-level major freeze (storage layer major compaction) if the replicas of the corresponding partition are in an inconsistent state.
• You cannot initiate a partition-level major freeze (storage layer major compaction) if the corresponding partition is being restored or transferred.
• You cannot initiate a partition-level major freeze (storage layer major compaction) if the major freeze (storage layer major compaction) is suspended.
• A partition-level major freeze (storage layer major compaction) is a major freeze (storage layer major compaction) performed on multiple replicas of the same partition. It consumes CPU and disk I/O resources. Before you initiate a partition-level major freeze (storage layer major compaction), you need to evaluate the resource usage of the current tenant. After the partition-level major freeze (storage layer major compaction) is initiated, the CPU and I/O usage will increase.

Examples

Example of major compaction

• The sys tenant initiates a major compaction for itself.

  obclient> ALTER SYSTEM MAJOR FREEZE;
  

• The sys tenant initiates a major compaction for all user tenants except the sys tenant and the Meta tenant.

  obclient> ALTER SYSTEM MAJOR FREEZE TENANT = all_user;
  

• The sys tenant initiates a major compaction for all Meta tenants.

  obclient> ALTER SYSTEM MAJOR FREEZE TENANT = all_meta;
  

• The sys tenant initiates a major compaction for the tenant1 and tenant2 tenants.

  obclient> ALTER SYSTEM MAJOR FREEZE TENANT = tenant1,tenant2;
  

Example of major dump

• The sys tenant initiates a major dump for itself.

  obclient> ALTER SYSTEM MINOR FREEZE;
  

• The sys tenant initiates a major dump for all user tenants except the sys tenant and the Meta tenant.

  obclient> ALTER SYSTEM MINOR FREEZE TENANT = all_user;
  

• The sys tenant initiates a major dump for all Meta tenants.

  obclient> ALTER SYSTEM MINOR FREEZE TENANT = all_meta;
  

• The sys tenant initiates a major dump for the tenant1 and tenant2 tenants.

  obclient> ALTER SYSTEM MINOR FREEZE TENANT = tenant1,tenant2;
  

• The sys tenant initiates a major dump for a specified partition under the tenant1 tenant.

  obclient> ALTER SYSTEM MINOR FREEZE tenant = tenant1 tablet_id = 1100611139453887;
  

• The sys tenant initiates a major dump for a specified OBServer node.

  obclient> ALTER SYSTEM MINOR FREEZE SERVER = ('10.XXX.XXX.XXX:2882');
  

• The sys tenant initiates a major dump for a specified log stream under the tenant1 tenant.

  obclient> ALTER SYSTEM MINOR FREEZE tenant = tenant1 LS 1;
  

• The sys tenant initiates a major dump for a specified partition under a specified log stream under the tenant1 tenant.

  obclient> ALTER SYSTEM MINOR FREEZE tenant = tenant1 ls 1 tablet_id = 60000;
  

Example of pausing or resuming major compaction

• The sys tenant pauses a major compaction for all user tenants except the sys tenant and the Meta tenant.

  obclient> ALTER SYSTEM SUSPEND MERGE TENANT = all_user;
  

• The sys tenant pauses a major compaction for the tenant1 and tenant2 tenants.

  obclient> ALTER SYSTEM SUSPEND MERGE TENANT = tenant1,tenant2;
  

• The sys tenant pauses a major compaction for all Meta tenants.

  obclient> ALTER SYSTEM SUSPEND MERGE TENANT = all_meta;
  

• The sys tenant resumes a major compaction for all user tenants except the sys tenant and the Meta tenant.

  obclient> ALTER SYSTEM RESUME MERGE TENANT = all_user;
  

• The sys tenant resumes a major compaction for the tenant1 and tenant2 tenants.

  obclient> ALTER SYSTEM RESUME MERGE TENANT = tenant1,tenant2;
  

• The sys tenant resumes a major compaction for all Meta tenants.

  obclient> ALTER SYSTEM RESUME MERGE TENANT = all_meta;
  

Example of clearing the major compaction error flag

• The sys tenant clears the major compaction error flag for all user tenants except the sys tenant and the Meta tenant.

  obclient> ALTER SYSTEM CLEAR MERGE ERROR TENANT = all_user;
  

• The sys tenant clears the major compaction error flag for the tenant1 and tenant2 tenants.

  obclient> ALTER SYSTEM CLEAR MERGE ERROR TENANT = tenant1,tenant2;
  

• The sys tenant clears the major compaction error flag for all Meta tenants.

  obclient> ALTER SYSTEM CLEAR MERGE ERROR TENANT = all_meta;
  

Example of initiating a major compaction at the table level

1. The sys tenant queries the table_id of the table tbl2 to be compacted.

   obclient(root@sys)[oceanbase]> SELECT a.tenant_id, b.tenant_name, a.database_name, a.table_id, a.table_name FROM oceanbase.CDB_OB_TABLE_LOCATIONS a, oceanbase.DBA_OB_TENANTS b 
   WHERE a.tenant_id=b.tenant_id 
   AND a.table_name = 'tbl2'
   AND b.tenant_name = 'mysql001';
   

   The query result is as follows:

   +-----------+-------------+---------------+----------+------------+
   | tenant_id | tenant_name | database_name | table_id | table_name |
   +-----------+-------------+---------------+----------+------------+
   |      1002 | mysql001    | test          |   500002 | tbl2       |
   +-----------+-------------+---------------+----------+------------+
   1 row in set
   

2. Execute the following statement to initiate a major compaction at the table level.

   obclient(root@sys)[oceanbase]> ALTER SYSTEM MAJOR FREEZE TENANT = mysql001 TABLE_ID = 500002;
   

Example of initiating a major compaction at the partition level

1. Query the TABLET ID of the table.

   Here is an example:

   obclient> SELECT a.tenant_id, b.tenant_name, a.database_name, a.table_id, a.table_name, a.tablet_id, a.PARTITION_NAME, a.SUBPARTITION_NAME
   FROM oceanbase.CDB_OB_TABLE_LOCATIONS a, oceanbase.DBA_OB_TENANTS b
   WHERE a.tenant_id=b.tenant_id
   AND a.table_name = 'test_tbl1'
   AND b.tenant_name = 'oracle001';
   

   The query result is as follows:

   +-----------+-------------+---------------+----------+------------+-----------+----------------+-------------------+
   | tenant_id | tenant_name | database_name | table_id | table_name | tablet_id | PARTITION_NAME | SUBPARTITION_NAME |
   +-----------+-------------+---------------+----------+------------+-----------+----------------+-------------------+
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200008 | P1             | SP0               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200009 | P1             | SP1               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200010 | P1             | SP2               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200011 | P1             | SP3               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200012 | P2             | SP4               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200013 | P2             | SP5               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200014 | P2             | SP6               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200015 | P2             | SP7               |
   +-----------+-------------+---------------+----------+------------+-----------+----------------+-------------------+
   8 rows in set
   

   For more information about the view fields, see oceanbase.CDB_OB_TABLE_LOCATIONS.

2. Initiate a major compaction.

   Here is an example:

   obclient> ALTER SYSTEM MAJOR FREEZE TENANT = oracle001 TABLET_ID = 200008;
   

Example of initiating a major dump at the partition level

1. Query the TABLET ID of the table.

   Here is an example:

   obclient> SELECT t1.tenant_id, t2.tenant_name, t1.database_name, t1.table_id, t1.table_name, t1.tablet_id, t1.PARTITION_NAME, t1.SUBPARTITION_NAME
   FROM oceanbase.CDB_OB_TABLE_LOCATIONS t1, oceanbase.DBA_OB_TENANTS t2
   WHERE t1.tenant_id=t2.tenant_id
   AND t1.table_name = 'test_tbl1'
   AND t2.tenant_name = 'oracle001';
   

   The query result is as follows:

   +-----------+-------------+---------------+----------+------------+-----------+----------------+-------------------+
   | tenant_id | tenant_name | database_name | table_id | table_name | tablet_id | PARTITION_NAME | SUBPARTITION_NAME |
   +-----------+-------------+---------------+----------+------------+-----------+----------------+-------------------+
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200008 | P1             | SP0               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200009 | P1             | SP1               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200010 | P1             | SP2               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200011 | P1             | SP3               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200012 | P2             | SP4               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200013 | P2             | SP5               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200014 | P2             | SP6               |
   |      1004 | oracle001   | SYS           |   500011 | TEST_TBL1  |    200015 | P2             | SP7               |
   +-----------+-------------+---------------+----------+------------+-----------+----------------+-------------------+
   8 rows in set
   

   For more information about the view fields, see oceanbase.CDB_OB_TABLE_LOCATIONS.

2. Initiate a major dump.

   Here is an example:

   obclient> ALTER SYSTEM MINOR FREEZE TENANT = oracle001 TABLET_ID = 200008;
   

References

• Overview of merge management
• Manually trigger a merge
• View merge information
• Overview of dump management
• Manually trigger a dump
• View dump information