AWS Database Migration Service
User Guide (Version API Version 2016-01-01)

Target Metadata Task Settings

Target metadata settings include the following:

  • TargetSchema – The target table schema name. If this metadata option is empty, the schema from the source table is used. AWS DMS automatically adds the owner prefix for the target database to all tables if no source schema is defined. This option should be left empty for MySQL-type target endpoints.

  • LOB settings – Settings that determine how large objects (LOBs) are managed. If you set SupportLobs=true, you must set one of the following to true:

    • FullLobMode – If you set this option to true, then you must enter a value for the LobChunkSize option. Enter the size, in kilobytes, of the LOB chunks to use when replicating the data to the target. The FullLobMode option works best for very large LOB sizes but tends to cause slower loading.

    • InlineLobMaxSize – This value determines which LOBs AWS Database Migration Service transfers inline during a full load. Transferring small LOBs is more efficient than looking them up from a source table. During a full load, AWS Database Migration Service checks all LOBs and performs an inline transfer for the LOBs that are smaller than InlineLobMaxSize. AWS Database Migration Service transfers all LOBs larger than the InlineLobMaxSize in FullLobMode. The default value for InlineLobMaxSize is 0 and the range is 1 kilobyte–2 gigabyte. Set a value for InlineLobMaxSize only if you know that most of the LOBs are smaller than the value specified in InlineLobMaxSize.

    • LimitedSizeLobMode – If you set this option to true, then you must enter a value for the LobMaxSize option. Enter the maximum size, in kilobytes, for an individual LOB.

  • LoadMaxFileSize – An option for PostgreSQL and MySQL target endpoints that defines the maximum size on disk of stored, unloaded data, such as CSV files. This option overrides the connection attribute. You can provide values from 0, which indicates that this option doesn't override the connection attribute, to 100,000 KB.

  • BatchApplyEnabled – Determines if each transaction is applied individually or if changes are committed in batches. The default value is false.

    The BatchApplyEnabled parameter is used with the BatchApplyPreserveTransaction parameter. If BatchApplyEnabled is set to true, then the BatchApplyPreserveTransaction parameter determines the transactional integrity.

    If BatchApplyPreserveTransaction is set to true, then transactional integrity is preserved and a batch is guaranteed to contain all the changes within a transaction from the source.

    If BatchApplyPreserveTransaction is set to false, then there can be temporary lapses in transactional integrity to improve performance.

    The BatchApplyPreserveTransaction parameter applies only to Oracle target endpoints, and is only relevant when the BatchApplyEnabled parameter is set to true.

    When LOB columns are included in the replication, BatchApplyEnabledcan only be used in Limited-size LOB mode.

  • ParallelLoadThreads – Specifies the number of threads AWS DMS uses to load each table into the target database. The maximum value for a MySQL target is 16; the maximum value for a DynamoDB target is 32. The maximum limit can be increased upon request.

  • ParallelLoadBufferSize – Specifies the maximum number of records to store in the buffer used by the parallel load threads to load data to the target. The default value is 50. Maximum value is 1000. This field is currently only valid when DynamoDB is the target. This parameter should be used with ParallelLoadThreads and is valid only when ParallelLoadThreads > 1.