# How to Reindex in Amazon OpenSearch Serverless Using Amazon OpenSearch Ingestion on AWS
Amazon OpenSearch Service, formerly known as Amazon Elasticsearch Service, is a managed service that makes it easy to deploy, operate, and scale OpenSearch clusters in the AWS Cloud. With the introduction of Amazon OpenSearch Serverless, users can now enjoy a more streamlined and cost-effective way to manage their search and analytics workloads without worrying about the underlying infrastructure. One common task in managing search indices is reindexing, which involves copying data from one index to another. This article will guide you through the process of reindexing in Amazon OpenSearch Serverless using Amazon OpenSearch Ingestion.
## What is Reindexing?
Reindexing is the process of copying documents from one index to another. This is often necessary when you need to:
– Change the mapping of an index.
– Upgrade to a new version of OpenSearch.
– Optimize performance by restructuring your data.
– Migrate data between clusters.
## Prerequisites
Before you start, ensure you have the following:
1. An AWS account with appropriate permissions.
2. An Amazon OpenSearch Serverless collection.
3. Amazon OpenSearch Ingestion pipelines set up.
4. Basic knowledge of OpenSearch and its APIs.
## Step-by-Step Guide to Reindexing
### Step 1: Set Up Your Source and Destination Indices
First, identify the source index (the index you want to reindex from) and create a destination index (the index you want to reindex to). You can create a new index with the desired mappings and settings using the OpenSearch API.
“`json
PUT /destination-index
{
“settings”: {
“number_of_shards”: 3,
“number_of_replicas”: 2
},
“mappings”: {
“properties”: {
“field1”: { “type”: “text” },
“field2”: { “type”: “keyword” }
}
}
}
“`
### Step 2: Configure Amazon OpenSearch Ingestion
Amazon OpenSearch Ingestion is a fully managed service that allows you to ingest and transform data before indexing it into OpenSearch. To use it for reindexing, you need to set up an ingestion pipeline.
1. **Create an Ingestion Pipeline:**
Navigate to the Amazon OpenSearch Ingestion console and create a new pipeline. Define the source as your existing OpenSearch index and the destination as your new index.
2. **Configure the Pipeline:**
Use the following configuration as a template:
“`json
{
“source”: {
“opensearch”: {
“hosts”: [“https://source-opensearch-domain”],
“index”: “source-index”
}
},
“dest”: {
“opensearch”: {
“hosts”: [“https://destination-opensearch-domain”],
“index”: “destination-index”
}
},
“transform”: {
“script”: {
“source”: “ctx._source.field3 = ctx._source.field1 + ‘ ‘ + ctx._source.field2”
}
}
}
“`
This configuration reads data from the `source-index`, applies a transformation (if needed), and writes it to the `destination-index`.
### Step 3: Execute the Reindexing Process
Once your pipeline is configured, you can start the reindexing process. This can be done through the AWS Management Console or using the AWS CLI.
**Using AWS CLI:**
“`sh
aws opensearch-ingestion start-pipeline –pipeline-name my-reindex-pipeline
“`
### Step 4: Monitor the Reindexing Process
Monitoring is crucial to ensure that the reindexing process completes successfully. You can monitor the status of your ingestion pipeline through the Amazon OpenSearch Ingestion console or by using CloudWatch metrics.
**Using CloudWatch:**
1. Navigate to the CloudWatch console.
2. Select Metrics and filter by `OpenSearchIngestion`.
3. Monitor metrics such as `DocumentsProcessed`, `DocumentsFailed`, and `PipelineStatus`.
### Step 5: Validate the Reindexed Data
After the reindexing process is complete, validate that all documents have been correctly copied to the new index. You can do this by comparing document counts and sampling documents from both indices.
**Using OpenSearch API:**
“`json
GET /destination-index/_count
“`
Compare this count with the source index:
“`json
GET /source-index/_count
“`
Additionally, sample some documents from both indices to ensure data integrity.
### Step 6: Clean Up
Once you have validated that the reindexing process was successful, you can clean up any temporary resources you created, such as the ingestion pipeline.
**Using AWS CLI:**
“`sh
aws opensearch-ingestion delete-pipeline –pipeline-name my-re