Reindex documents Added in 2.3.0

POST /_reindex

Copy documents from a source to a destination. You can copy all documents to the destination index or reindex a subset of the documents. The source can be any existing index, alias, or data stream. The destination must differ from the source. For example, you cannot reindex a data stream into itself.

IMPORTANT: Reindex requires _source to be enabled for all documents in the source. The destination should be configured as wanted before calling the reindex API. Reindex does not copy the settings from the source or its associated template. Mappings, shard counts, and replicas, for example, must be configured ahead of time.

If the Elasticsearch security features are enabled, you must have the following security privileges:

  • The read index privilege for the source data stream, index, or alias.
  • The write index privilege for the destination data stream, index, or index alias.
  • To automatically create a data stream or index with a reindex API request, you must have the auto_configure, create_index, or manage index privilege for the destination data stream, index, or alias.
  • If reindexing from a remote cluster, the source.remote.user must have the monitor cluster privilege and the read index privilege for the source data stream, index, or alias.

If reindexing from a remote cluster, you must explicitly allow the remote host in the reindex.remote.whitelist setting. Automatic data stream creation requires a matching index template with data stream enabled.

The dest element can be configured like the index API to control optimistic concurrency control. Omitting version_type or setting it to internal causes Elasticsearch to blindly dump documents into the destination, overwriting any that happen to have the same ID.

Setting version_type to external causes Elasticsearch to preserve the version from the source, create any documents that are missing, and update any documents that have an older version in the destination than they do in the source.

Setting op_type to create causes the reindex API to create only missing documents in the destination. All existing documents will cause a version conflict.

IMPORTANT: Because data streams are append-only, any reindex request to a destination data stream must have an op_type of create. A reindex can only add new documents to a destination data stream. It cannot update existing documents in a destination data stream.

By default, version conflicts abort the reindex process. To continue reindexing if there are conflicts, set the conflicts request body property to proceed. In this case, the response includes a count of the version conflicts that were encountered. Note that the handling of other error types is unaffected by the conflicts property. Additionally, if you opt to count version conflicts, the operation could attempt to reindex more documents from the source than max_docs until it has successfully indexed max_docs documents into the target or it has gone through every document in the source query.

NOTE: The reindex API makes no effort to handle ID collisions. The last document written will "win" but the order isn't usually predictable so it is not a good idea to rely on this behavior. Instead, make sure that IDs are unique by using a script.

Running reindex asynchronously

If the request contains wait_for_completion=false, Elasticsearch performs some preflight checks, launches the request, and returns a task you can use to cancel or get the status of the task. Elasticsearch creates a record of this task as a document at _tasks/<task_id>.

Reindex from multiple sources

If you have many sources to reindex it is generally better to reindex them one at a time rather than using a glob pattern to pick up multiple sources. That way you can resume the process if there are any errors by removing the partially completed source and starting over. It also makes parallelizing the process fairly simple: split the list of sources to reindex and run each list in parallel.

For example, you can use a bash script like this:

for index in i1 i2 i3 i4 i5; do
  curl -HContent-Type:application/json -XPOST localhost:9200/_reindex?pretty -d'{
    "source": {
      "index": "'$index'"
    },
    "dest": {
      "index": "'$index'-reindexed"
    }
  }'
done

** Throttling**

Set requests_per_second to any positive decimal number (1.4, 6, 1000, for example) to throttle the rate at which reindex issues batches of index operations. Requests are throttled by padding each batch with a wait time. To turn off throttling, set requests_per_second to -1.

The throttling is done by waiting between batches so that the scroll that reindex uses internally can be given a timeout that takes into account the padding. The padding time is the difference between the batch size divided by the requests_per_second and the time spent writing. By default the batch size is 1000, so if requests_per_second is set to 500:

target_time = 1000 / 500 per second = 2 seconds
wait_time = target_time - write_time = 2 seconds - .5 seconds = 1.5 seconds

Since the batch is issued as a single bulk request, large batch sizes cause Elasticsearch to create many requests and then wait for a while before starting the next set. This is "bursty" instead of "smooth".

Slicing

Reindex supports sliced scroll to parallelize the reindexing process. This parallelization can improve efficiency and provide a convenient way to break the request down into smaller parts.

NOTE: Reindexing from remote clusters does not support manual or automatic slicing.

You can slice a reindex request manually by providing a slice ID and total number of slices to each request. You can also let reindex automatically parallelize by using sliced scroll to slice on _id. The slices parameter specifies the number of slices to use.

Adding slices to the reindex request just automates the manual process, creating sub-requests which means it has some quirks:

  • You can see these requests in the tasks API. These sub-requests are "child" tasks of the task for the request with slices.
  • Fetching the status of the task for the request with slices only contains the status of completed slices.
  • These sub-requests are individually addressable for things like cancellation and rethrottling.
  • Rethrottling the request with slices will rethrottle the unfinished sub-request proportionally.
  • Canceling the request with slices will cancel each sub-request.
  • Due to the nature of slices, each sub-request won't get a perfectly even portion of the documents. All documents will be addressed, but some slices may be larger than others. Expect larger slices to have a more even distribution.
  • Parameters like requests_per_second and max_docs on a request with slices are distributed proportionally to each sub-request. Combine that with the previous point about distribution being uneven and you should conclude that using max_docs with slices might not result in exactly max_docs documents being reindexed.
  • Each sub-request gets a slightly different snapshot of the source, though these are all taken at approximately the same time.

If slicing automatically, setting slices to auto will choose a reasonable number for most indices. If slicing manually or otherwise tuning automatic slicing, use the following guidelines.

Query performance is most efficient when the number of slices is equal to the number of shards in the index. If that number is large (for example, 500), choose a lower number as too many slices will hurt performance. Setting slices higher than the number of shards generally does not improve efficiency and adds overhead.

Indexing performance scales linearly across available resources with the number of slices.

Whether query or indexing performance dominates the runtime depends on the documents being reindexed and cluster resources.

Modify documents during reindexing

Like _update_by_query, reindex operations support a script that modifies the document. Unlike _update_by_query, the script is allowed to modify the document's metadata.

Just as in _update_by_query, you can set ctx.op to change the operation that is run on the destination. For example, set ctx.op to noop if your script decides that the document doesn’t have to be indexed in the destination. This "no operation" will be reported in the noop counter in the response body. Set ctx.op to delete if your script decides that the document must be deleted from the destination. The deletion will be reported in the deleted counter in the response body. Setting ctx.op to anything else will return an error, as will setting any other field in ctx.

Think of the possibilities! Just be careful; you are able to change:

  • _id
  • _index
  • _version
  • _routing

Setting _version to null or clearing it from the ctx map is just like not sending the version in an indexing request. It will cause the document to be overwritten in the destination regardless of the version on the target or the version type you use in the reindex API.

Reindex from remote

Reindex supports reindexing from a remote Elasticsearch cluster. The host parameter must contain a scheme, host, port, and optional path. The username and password parameters are optional and when they are present the reindex operation will connect to the remote Elasticsearch node using basic authentication. Be sure to use HTTPS when using basic authentication or the password will be sent in plain text. There are a range of settings available to configure the behavior of the HTTPS connection.

When using Elastic Cloud, it is also possible to authenticate against the remote cluster through the use of a valid API key. Remote hosts must be explicitly allowed with the reindex.remote.whitelist setting. It can be set to a comma delimited list of allowed remote host and port combinations. Scheme is ignored; only the host and port are used. For example:

reindex.remote.whitelist: [otherhost:9200, another:9200, 127.0.10.*:9200, localhost:*"]

The list of allowed hosts must be configured on any nodes that will coordinate the reindex. This feature should work with remote clusters of any version of Elasticsearch. This should enable you to upgrade from any version of Elasticsearch to the current version by reindexing from a cluster of the old version.

WARNING: Elasticsearch does not support forward compatibility across major versions. For example, you cannot reindex from a 7.x cluster into a 6.x cluster.

To enable queries sent to older versions of Elasticsearch, the query parameter is sent directly to the remote host without validation or modification.

NOTE: Reindexing from remote clusters does not support manual or automatic slicing.

Reindexing from a remote server uses an on-heap buffer that defaults to a maximum size of 100mb. If the remote index includes very large documents you'll need to use a smaller batch size. It is also possible to set the socket read timeout on the remote connection with the socket_timeout field and the connection timeout with the connect_timeout field. Both default to 30 seconds.

Configuring SSL parameters

Reindex from remote supports configurable SSL settings. These must be specified in the elasticsearch.yml file, with the exception of the secure settings, which you add in the Elasticsearch keystore. It is not possible to configure SSL in the body of the reindex request.

Query parameters

  • refresh boolean

    If true, the request refreshes affected shards to make this operation visible to search.

  • The throttle for this request in sub-requests per second. By default, there is no throttle.

  • scroll string

    The period of time that a consistent view of the index should be maintained for scrolled search.

  • slices number | string

    The number of slices this task should be divided into. It defaults to one slice, which means the task isn't sliced into subtasks.

    Reindex supports sliced scroll to parallelize the reindexing process. This parallelization can improve efficiency and provide a convenient way to break the request down into smaller parts.

    NOTE: Reindexing from remote clusters does not support manual or automatic slicing.

    If set to auto, Elasticsearch chooses the number of slices to use. This setting will use one slice per shard, up to a certain limit. If there are multiple sources, it will choose the number of slices based on the index or backing index with the smallest number of shards.

  • timeout string

    The period each indexing waits for automatic index creation, dynamic mapping updates, and waiting for active shards. By default, Elasticsearch waits for at least one minute before failing. The actual wait time could be longer, particularly when multiple waits occur.

  • wait_for_active_shards number | string

    The number of shard copies that must be active before proceeding with the operation. Set it to all or any positive integer up to the total number of shards in the index (number_of_replicas+1). The default value is one, which means it waits for each primary shard to be active.

  • If true, the request blocks until the operation is complete.

  • If true, the destination must be an index alias.

application/json

Body Required

  • Values are abort or proceed.

  • dest object Required

    Additional properties are allowed.

    Hide dest attributes Show dest attributes object
  • max_docs number

    The maximum number of documents to reindex. By default, all documents are reindexed. If it is a value less then or equal to scroll_size, a scroll will not be used to retrieve the results for the operation.

    If conflicts is set to proceed, the reindex operation could attempt to reindex more documents from the source than max_docs until it has successfully indexed max_docs documents into the target or it has gone through every document in the source query.

  • script object

    Additional properties are allowed.

    Hide script attributes Show script attributes object
    • source string

      The script source.

    • id string
    • params object

      Specifies any named parameters that are passed into the script as variables. Use parameters instead of hard-coded values to decrease compile time.

      Hide params attribute Show params attribute object
      • * object Additional properties

        Additional properties are allowed.

    • lang string

      Any of:

      Values are painless, expression, mustache, or java.

    • options object
      Hide options attribute Show options attribute object
      • * string Additional properties
  • size number
  • source object Required

    Additional properties are allowed.

    Hide source attributes Show source attributes object
    • index string | array[string] Required
    • query object

      An Elasticsearch Query DSL (Domain Specific Language) object that defines a query.

      Additional properties are allowed.

    • remote object

      Additional properties are allowed.

      Hide remote attributes Show remote attributes object
      • A duration. Units can be nanos, micros, ms (milliseconds), s (seconds), m (minutes), h (hours) and d (days). Also accepts "0" without a unit and "-1" to indicate an unspecified value.

      • headers object

        An object containing the headers of the request.

        Hide headers attribute Show headers attribute object
        • * string Additional properties
      • host string Required
      • username string
      • password string
      • A duration. Units can be nanos, micros, ms (milliseconds), s (seconds), m (minutes), h (hours) and d (days). Also accepts "0" without a unit and "-1" to indicate an unspecified value.

    • size number

      The number of documents to index per batch. Use it when you are indexing from remote to ensure that the batches fit within the on-heap buffer, which defaults to a maximum size of 100 MB.

    • slice object

      Additional properties are allowed.

      Hide slice attributes Show slice attributes object
      • field string

        Path to field or array of paths. Some API's support wildcards in the path to select multiple fields.

      • id string Required
      • max number Required
    • sort string | object | array[string | object]

      One of:

      Path to field or array of paths. Some API's support wildcards in the path to select multiple fields.

    • _source string | array[string]
    • Hide runtime_mappings attribute Show runtime_mappings attribute object
      • * object Additional properties

        Additional properties are allowed.

        Hide * attributes Show * attributes object
        • fields object

          For type composite

          Hide fields attribute Show fields attribute object
          • * object Additional properties

            Additional properties are allowed.

            Hide * attribute Show * attribute object
            • type string Required

              Values are boolean, composite, date, double, geo_point, ip, keyword, long, or lookup.

        • fetch_fields array[object]

          For type lookup

          Hide fetch_fields attributes Show fetch_fields attributes object
          • field string Required

            Path to field or array of paths. Some API's support wildcards in the path to select multiple fields.

          • format string
        • format string

          A custom format for date type runtime fields.

        • Path to field or array of paths. Some API's support wildcards in the path to select multiple fields.

        • Path to field or array of paths. Some API's support wildcards in the path to select multiple fields.

        • script object

          Additional properties are allowed.

          Hide script attributes Show script attributes object
          • source string

            The script source.

          • id string
          • params object

            Specifies any named parameters that are passed into the script as variables. Use parameters instead of hard-coded values to decrease compile time.

            Hide params attribute Show params attribute object
            • * object Additional properties

              Additional properties are allowed.

          • lang string

            Any of:

            Values are painless, expression, mustache, or java.

          • options object
            Hide options attribute Show options attribute object
            • * string Additional properties
        • type string Required

          Values are boolean, composite, date, double, geo_point, ip, keyword, long, or lookup.

Responses

  • 200 application/json
    Hide response attributes Show response attributes object
    • batches number

      The number of scroll responses that were pulled back by the reindex.

    • created number

      The number of documents that were successfully created.

    • deleted number

      The number of documents that were successfully deleted.

    • failures array[object]

      If there were any unrecoverable errors during the process, it is an array of those failures. If this array is not empty, the request ended because of those failures. Reindex is implemented using batches and any failure causes the entire process to end but all failures in the current batch are collected into the array. You can use the conflicts option to prevent the reindex from ending on version conflicts.

      Hide failures attributes Show failures attributes object
      • cause object Required

        Additional properties are allowed.

        Hide cause attributes Show cause attributes object
        • type string Required

          The type of error

        • reason string

          A human-readable explanation of the error, in English.

        • The server stack trace. Present only if the error_trace=true parameter was sent with the request.

        • Additional properties are allowed.

        • root_cause array[object]

          Additional properties are allowed.

        • suppressed array[object]

          Additional properties are allowed.

      • id string Required
      • index string Required
      • status number Required
      • type string Required
    • noops number

      The number of documents that were ignored because the script used for the reindex returned a noop value for ctx.op.

    • retries object

      Additional properties are allowed.

      Hide retries attributes Show retries attributes object
      • bulk number Required

        The number of bulk actions retried.

    • The number of requests per second effectively run during the reindex.

    • slice_id number
    • Time unit for milliseconds

    • Time unit for milliseconds

    • timed_out boolean

      If any of the requests that ran during the reindex timed out, it is true.

    • took number

      Time unit for milliseconds

    • total number

      The number of documents that were successfully processed.

    • updated number

      The number of documents that were successfully updated. That is to say, a document with the same ID already existed before the reindex updated it.

    • The number of version conflicts that occurred.

POST /_reindex
curl \
 -X POST http://api.example.com/_reindex \
 -H "Content-Type: application/json" \
 -d '{"conflicts":"abort","dest":{"index":"string","op_type":"index","pipeline":"string","routing":"string","version_type":"internal"},"max_docs":42.0,"script":{"source":"string","id":"string","params":{"additionalProperty1":{},"additionalProperty2":{}},"":"painless","options":{"additionalProperty1":"string","additionalProperty2":"string"}},"size":42.0,"source":{"index":"string","query":{},"remote":{"connect_timeout":"string","headers":{"additionalProperty1":"string","additionalProperty2":"string"},"host":"string","username":"string","password":"string","socket_timeout":"string"},"size":42.0,"slice":{"field":"string","id":"string","max":42.0},"":"string","_source":"string","runtime_mappings":{"additionalProperty1":{"fields":{"additionalProperty1":{"type":"boolean"},"additionalProperty2":{"type":"boolean"}},"fetch_fields":[{"field":"string","format":"string"}],"format":"string","input_field":"string","target_field":"string","target_index":"string","script":{"source":"string","id":"string","params":{"additionalProperty1":{},"additionalProperty2":{}},"":"painless","options":{"additionalProperty1":"string","additionalProperty2":"string"}},"type":"boolean"},"additionalProperty2":{"fields":{"additionalProperty1":{"type":"boolean"},"additionalProperty2":{"type":"boolean"}},"fetch_fields":[{"field":"string","format":"string"}],"format":"string","input_field":"string","target_field":"string","target_index":"string","script":{"source":"string","id":"string","params":{"additionalProperty1":{},"additionalProperty2":{}},"":"painless","options":{"additionalProperty1":"string","additionalProperty2":"string"}},"type":"boolean"}}}}'
Request examples
{
  "conflicts": "abort",
  "dest": {
    "index": "string",
    "op_type": "index",
    "pipeline": "string",
    "routing": "string",
    "version_type": "internal"
  },
  "max_docs": 42.0,
  "script": {
    "source": "string",
    "id": "string",
    "params": {
      "additionalProperty1": {},
      "additionalProperty2": {}
    },
    "": "painless",
    "options": {
      "additionalProperty1": "string",
      "additionalProperty2": "string"
    }
  },
  "size": 42.0,
  "source": {
    "index": "string",
    "query": {},
    "remote": {
      "connect_timeout": "string",
      "headers": {
        "additionalProperty1": "string",
        "additionalProperty2": "string"
      },
      "host": "string",
      "username": "string",
      "password": "string",
      "socket_timeout": "string"
    },
    "size": 42.0,
    "slice": {
      "field": "string",
      "id": "string",
      "max": 42.0
    },
    "": "string",
    "_source": "string",
    "runtime_mappings": {
      "additionalProperty1": {
        "fields": {
          "additionalProperty1": {
            "type": "boolean"
          },
          "additionalProperty2": {
            "type": "boolean"
          }
        },
        "fetch_fields": [
          {
            "field": "string",
            "format": "string"
          }
        ],
        "format": "string",
        "input_field": "string",
        "target_field": "string",
        "target_index": "string",
        "script": {
          "source": "string",
          "id": "string",
          "params": {
            "additionalProperty1": {},
            "additionalProperty2": {}
          },
          "": "painless",
          "options": {
            "additionalProperty1": "string",
            "additionalProperty2": "string"
          }
        },
        "type": "boolean"
      },
      "additionalProperty2": {
        "fields": {
          "additionalProperty1": {
            "type": "boolean"
          },
          "additionalProperty2": {
            "type": "boolean"
          }
        },
        "fetch_fields": [
          {
            "field": "string",
            "format": "string"
          }
        ],
        "format": "string",
        "input_field": "string",
        "target_field": "string",
        "target_index": "string",
        "script": {
          "source": "string",
          "id": "string",
          "params": {
            "additionalProperty1": {},
            "additionalProperty2": {}
          },
          "": "painless",
          "options": {
            "additionalProperty1": "string",
            "additionalProperty2": "string"
          }
        },
        "type": "boolean"
      }
    }
  }
}
Response examples (200)
{
  "batches": 42.0,
  "created": 42.0,
  "deleted": 42.0,
  "failures": [
    {
      "cause": {
        "type": "string",
        "reason": "string",
        "stack_trace": "string",
        "caused_by": {},
        "root_cause": [
          {}
        ],
        "suppressed": [
          {}
        ]
      },
      "id": "string",
      "index": "string",
      "status": 42.0,
      "type": "string"
    }
  ],
  "noops": 42.0,
  "retries": {
    "bulk": 42.0,
    "search": 42.0
  },
  "requests_per_second": 42.0,
  "slice_id": 42.0,
  "": 42.0,
  "timed_out": true,
  "total": 42.0,
  "updated": 42.0,
  "version_conflicts": 42.0
}