Manually initiate a major compaction

You can manually initiate a major compaction.

Prerequisites

Before a major compaction is triggered, make sure that global major compaction is enabled. Global major compaction is controlled by the cluster-level parameter enable_major_freeze. The default value is True, which specifies to enable global major compaction.

If global major compaction is disabled for the current cluster, perform the following steps to enable this feature:

1. Log on to the sys tenant of the cluster as the root user.

2. Verify that global major compaction is enabled.

   obclient> SHOW PARAMETERS LIKE 'enable_major_freeze';
   

3. If global major compaction is not enabled, execute the following statement to enable the feature.

   obclient> ALTER SYSTEM SET enable_major_freeze='True';
   

   For more information about the enable_major_freeze parameter, see enable_major_freeze.

Manually initiate a major compaction from the sys tenant

You can initiate a major compaction for the current tenant, all tenants, or specified tenants from the sys tenant.

To do so, perform the following steps:

1. Log on to the sys tenant of the cluster as the root user.

2. Use the following syntax to initiate a major compaction:

   obclient> ALTER SYSTEM MAJOR FREEZE TENANT [=] all_user | all | all_meta | tenant_name [, tenant_name ...];
   

   Here, [=] indicates that the equal sign (=) is optional.

   Here are some examples:

   • Initiate a major compaction for the sys tenant

     obclient> ALTER SYSTEM MAJOR FREEZE TENANT;
     

   • Initiate a major compaction for all user tenants from the sys tenant

     obclient> ALTER SYSTEM MAJOR FREEZE TENANT = all_user;
     

     or

     obclient> ALTER SYSTEM MAJOR FREEZE TENANT = all;
     

     Note

     In OceanBase Database V4.2.1 and later, the TENANT = all_user and TENANT = all settings express the same semantics. If you want an operation to take effect on all tenants, we recommend that you use TENANT = all_user. TENANT = all will be deprecated.

   • Initiate a major compaction for all meta tenants from the sys tenant

     obclient> ALTER SYSTEM MAJOR FREEZE TENANT = all_meta;
     

   • Initiate a major compaction for a specified tenant from the sys tenant

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

Manually initiate a major compaction for a user tenant

A user tenant can initiate a major compaction only for itself.

1. Log on to the database as an administrator of a user tenant.

2. Initiate a major compaction for the current tenant.

   obclient> ALTER SYSTEM MAJOR FREEZE;
   

References

• Automatically trigger a major compaction

• Configure scheduled major compactions

• Manually control a major compaction

• View the major compaction process