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Reindex data
After creating an index, you might need to make an extensive change such as adding a new field to every document or combining multiple indexes to form a new one. Rather than deleting your index, making the change offline, and then indexing your data again, you can use the reindex
operation.
With the reindex
operation, you can copy all or a subset of documents that you select through a query to another index. Reindex is a POST
operation. In its most basic form, you specify a source index and a destination index.
Reindexing can be an expensive operation depending on the size of your source index. We recommend you disable replicas in your destination index by setting number_of_replicas
to 0
and re-enable them once the reindex process is complete.
Table of contents
- Reindex all documents
- Reindex from a remote cluster
- Reindex a subset of documents
- Combine one or more indexes
- Reindex only unique documents
- Transform documents during reindexing
- Update documents in the current index
- Source index options
- Destination index options
Reindex all documents
You can copy all documents from one index to another.
You first need to create a destination index with your desired field mappings and settings or you can copy the ones from your source index:
PUT destination
{
"mappings":{
"Add in your desired mappings"
},
"settings":{
"Add in your desired settings"
}
}
This reindex
command copies all the documents from a source index to a destination index:
POST _reindex
{
"source":{
"index":"source"
},
"dest":{
"index":"destination"
}
}
If the destination index is not already created, the reindex
operation creates a new destination index with default configurations.
Reindex from a remote cluster
You can copy documents from an index in a remote cluster. Use the remote
option to specify the remote hostname and the required login credentials.
This command reaches out to a remote cluster, logs in with the username and password, and copies all the documents from the source index in that remote cluster to the destination index in your local cluster:
POST _reindex
{
"source":{
"remote":{
"host":"https://<REST_endpoint_of_remote_cluster>:9200",
"username":"YOUR_USERNAME",
"password":"YOUR_PASSWORD"
},
"index": "source"
},
"dest":{
"index":"destination"
}
}
You can specify the following options:
Options | Valid values | Description | Required |
---|---|---|---|
host | String | The REST endpoint of the remote cluster. | Yes |
username | String | The username to log into the remote cluster. | No |
password | String | The password to log into the remote cluster. | No |
socket_timeout | Time Unit | The wait time for socket reads (default 30s). | No |
connect_timeout | Time Unit | The wait time for remote connection timeouts (default 30s). | No |
Reindex a subset of documents
You can copy a specific set of documents that match a search query.
This command copies only a subset of documents matched by a query operation to the destination index:
POST _reindex
{
"source":{
"index":"source",
"query": {
"match": {
"field_name": "text"
}
}
},
"dest":{
"index":"destination"
}
}
For a list of all query operations, see Full-text queries.
Combine one or more indexes
You can combine documents from one or more indexes by adding the source indexes as a list.
This command copies all documents from two source indexes to one destination index:
POST _reindex
{
"source":{
"index":[
"source_1",
"source_2"
]
},
"dest":{
"index":"destination"
}
}
Make sure the number of shards for your source and destination indexes is the same.
Reindex only unique documents
You can copy only documents missing from a destination index by setting the op_type
option to create
. In this case, if a document with the same ID already exists, the operation ignores the one from the source index. To ignore all version conflicts of documents, set the conflicts
option to proceed
.
POST _reindex
{
"conflicts":"proceed",
"source":{
"index":"source"
},
"dest":{
"index":"destination",
"op_type":"create"
}
}
Transform documents during reindexing
You can transform your data during the reindexing process using the script
option. We recommend Painless for scripting in OpenSearch.
This command runs the source index through a Painless script that increments a number
field inside an account
object before copying it to the destination index:
POST _reindex
{
"source":{
"index":"source"
},
"dest":{
"index":"destination"
},
"script":{
"lang":"painless",
"source":"ctx._account.number++"
}
}
You can also specify an ingest pipeline to transform your data during the reindexing process.
You would first have to create a pipeline with processors
defined. You have a number of different processors
available to use in your ingest pipeline.
Here’s a sample ingest pipeline that defines a split
processor that splits a text
field based on a space
separator and stores it in a new word
field. The script
processor is a Painless script that finds the length of the word
field and stores it in a new word_count
field. The remove
processor removes the test
field.
PUT _ingest/pipeline/pipeline-test
{
"description": "Splits the text field into a list. Computes the length of the 'word' field and stores it in a new 'word_count' field. Removes the 'test' field.",
"processors": [
{
"split": {
"field": "text",
"separator": "\\s+",
"target_field": "word"
},
}
{
"script": {
"lang": "painless",
"source": "ctx.word_count = ctx.word.length"
}
},
{
"remove": {
"field": "test"
}
}
]
}
After creating a pipeline, you can use the reindex
operation:
POST _reindex
{
"source": {
"index": "source",
},
"dest": {
"index": "destination",
"pipeline": "pipeline-test"
}
}
Update documents in the current index
To update the data in your current index itself without copying it to a different index, use the update_by_query
operation.
The update_by_query
operation is POST
operation that you can perform on a single index at a time.
POST <index_name>/_update_by_query
If you run this command with no parameters, it increments the version number for all documents in the index.
Source index options
You can specify the following options for your source index:
Option | Valid values | Description | Required |
---|---|---|---|
index | String | The name of the source index. You can provide multiple source indexes as a list. | Yes |
max_docs | Integer | The maximum number of documents to reindex. | No |
query | Object | The search query to use for the reindex operation. | No |
size | Integer | The number of documents to reindex. | No |
slice | String | Specify manual or automatic slicing to parallelize reindexing. | No |
Destination index options
You can specify the following options for your destination index:
Option | Valid values | Description | Required |
---|---|---|---|
index | String | The name of the destination index. | Yes |
version_type | Enum | The version type for the indexing operation. Valid values: internal, external, external_gt, external_gte. | No |