Replicate to pre-existing OpenSearch index using AWS DMS

Question

Is it possible for DMS to replicate data from AWS RDS (PostgreSQL) to OpenSearch into pre-existing index? For example, If I create a target index in OpenSearch with the same name as the source table in RDS.
If not possible, how can I configure index's shards/replicas count and other configuration before replicating data to it through DMS? Does the DMS create index with the default configuration of 5 primary shards and 1 replica count?
Thank you!

marcelops · Answer

No, DMS does not use an existing index in OpenSearch. Even if you create one beforehand, it will be ignored. DMS automatically creates the index with default settings: 5 shards and 1 replica.

If you want to define these settings (shards, replicas, mappings), you’ll need to use a different approach, such as:

**DMS → S3 → Lambda/Glue → OpenSearch**
or
**Use Logstash with a direct database connection.**

These alternatives allow you to create and control the index before sending the data.

Replicate to pre-existing OpenSearch index using AWS DMS

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