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Pre-configuration for Data Migration via DBLink

Document Type | Technical Information

Category | Migration

Applicable Product Version | 6F

Document Number | TMITI014

 

Overview

This guide provides instructions on the settings that must be configured in advance when migrating data via DB Link.
Note
This document was prepared under the following conditions.
  • Virtual Machine: Virtual Box
  • OS: CentOS 7
  • Tibero: Tibero6
  • Source, Target: Tibero6 (located on the same server)
 
 

Method

1. Set Table Logging (nologging)

Set the tables to be migrated to nologging mode to improve migration speed.
alter table username.table_name nologging;

 

2. Drop Indexes

Drop the indexes created on the tables to be migrated to improve migration speed. Make sure to secure the creation scripts for the indexes you drop in advance.
drop index username.index_name;

 

3. Table Parallelism and Append Processing

You can specify append processing and the degree of parallelism (DOP) for the tables to be migrated using hints. However, you must enable parallel DML at the session level beforehand, and perform a commit after migration is complete.
alter session enable parallel dml;
 
insert /*+ append parallel(4) */ into username.table_name select /*+ parallel(4) */ * 
from username.table_name@dblink_name;

commit;

 

4. No Archive Mode Setting

Set the archive mode of the target DB to noarchivelog mode to improve migration speed. This operation requires a database restart.
alter database noarchivelog;

 

5. Undo Retention Setting

Reduce the reuse time of the Undo Tablespace, which is most frequently used during data migration, to improve migration speed. This setting applies only to newly connected sessions after the change, and it is recommended to set a value below 100. The default value is 900 seconds (15 minutes).
alter system set undo_retention=30;

 

6. Disable and Drop Constraints

Constraints are checked for each row inserted into the target. Disabling or dropping constraints on the target can improve data migration speed. As with indexes, if you drop constraints, be sure to secure the creation scripts beforehand.
alter table username.table_name drop constraint constraint_name;
 
alter table username.table_name disable constraint constraint_name;

 

 

 

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