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Difficulty: MediumDatabase Migration and Schema Conversion using DMS and SCT

A company plans to transition their self-managed Oracle database to Amazon Aurora PostgreSQL-Compatible Edition. The database schemas have already been converted and applied to the target database. A Solutions Architect sets up an AWS Database Migration Service (AWS DMS) task configured for full load and ongoing replication (CDC). The full load phase completes successfully, but the task halts immediately when transitioning to the replication phase. Which two configuration steps must be performed on the source database to support ongoing replication? (Select two.)

  1. Ensure that the source database is configured to run in ARCHIVELOG mode.Answer
  2. Enable minimal supplemental logging and table-level supplemental logging on the source database.Answer
  3. C
    Enable supplemental logging on the target database tables.
  4. D
    Configure the target database to write changes to local write-ahead logs (WAL) before applying them.
  5. E
    Configure the AWS DMS source endpoint with extra connection attributes to disable the reading of online redo logs.

Answer

To support ongoing replication (CDC) from a source Oracle database, you must configure the source database to run in ARCHIVELOG mode and enable minimal supplemental logging and table-level supplemental logging on it.
To perform ongoing replication (CDC) from an Oracle source database, AWS DMS must read the transaction logs. This requires the source database to be in ARCHIVELOG mode so that transaction log files are archived and accessible. Additionally, supplemental logging must be enabled on the source database so that it writes sufficient column data to the redo logs for DMS to reconstruct the database changes.

Step-by-Step Solution

1
Analyze the point of failure in the AWS DMS task.
The task succeeded during the full load phase but halted immediately when transitioning to ongoing replication (CDC).
This indicates that the source database is not generating or preserving the transaction logs in a format that AWS DMS can capture and read.
2
Determine the source database requirements for AWS DMS CDC.
For Oracle sources, AWS DMS requires the database to run in ARCHIVELOG mode to preserve redo logs.
ARCHIVELOG mode ensures that logs are archived and not immediately overwritten, allowing AWS DMS to capture changes that occurred since the migration started.
3
Verify database supplemental logging requirements.
Enable minimal supplemental logging at the database level and table-level supplemental logging.
By default, Oracle does not write enough database change information to the logs. Supplemental logging ensures that full column updates are written to the redo logs, which is required for DMS to reconstruct changes.

Key Concept

Configuring the source database transaction logs (ARCHIVELOG mode and supplemental logging) is mandatory for AWS DMS Change Data Capture (CDC) replication to succeed.
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Topics

Database Migration and Schema Conversion using DMS and SCT

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