Manually initiate a major compaction

You can manually initiate a major compaction.

Prerequisites

To enable the system to automatically trigger a major compaction, make sure that global major compaction is enabled. Global major compaction is specified 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 in to the sys tenant of the cluster as the root user.

2. Verify whether 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';
   

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 in to the sys tenant of the cluster as the root user.

2. Initiate a major compaction.

   The SQL syntax is as follows:

   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;
     

   • 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, TENANT = all_user and TENANT = all express the same semantics. If you want an operation to take effect on all user 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 major compactions for specified tenants from the sys tenant

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

Manually initiate a major compaction from a user tenant

In a user tenant, you can initiate a major compaction only for the current tenant.

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

2. Initiate a major compaction for the current tenant.

   The SQL syntax is as follows:

   obclient> ALTER SYSTEM MAJOR FREEZE;
   

References

• Automatically trigger a major compaction

• Configure scheduled major compactions

• Manually manage a major compaction

• View the major compaction process