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Reindex API

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Reindex API

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Copies documents from a source to a destination.

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.

Reindex requires _source to be enabled for all documents in the source.

The destination should be configured as wanted before calling _reindex. Reindex does not copy the settings from the source or its associated template.

Mappings, shard counts, replicas, and so on must be configured ahead of time.

resp = client.reindex(
    source={
        "index": "my-index-000001"
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001'
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: "my-index-000001",
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "my-index-000001"
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

Request

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POST /_reindex

Prerequisites

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  • 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 an 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 of elasticsearch.yml. See Reindex from remote.
  • Automatic data stream creation requires a matching index template with data stream enabled. See Set up a data stream.

Description

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Extracts the document source from the source index and indexes the documents into the destination index. You can copy all documents to the destination index, or reindex a subset of the documents.

Just like _update_by_query, _reindex gets a snapshot of the source but its destination must be different so version conflicts are unlikely. 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 _reindex to only create missing documents in the destination. All existing documents will cause a version conflict.

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 parameter 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" parameter. 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.

Running reindex asynchronously

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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

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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.

One-off bash scripts seem to work nicely for 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

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Set requests_per_second to any positive decimal number (1.4, 6, 1000, etc.) to throttle the rate at which _reindex issues batches of index operations. Requests are throttled by padding each batch with a wait time. To disable 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".

Rethrottling

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The value of requests_per_second can be changed on a running reindex using the _rethrottle API:

$params = [
    'task_id' => 'r1A2WoRbTwKZ516z6NEs5A:36619',
];
$response = $client->reindexRethrottle($params);
resp = client.reindex_rethrottle(
    task_id="r1A2WoRbTwKZ516z6NEs5A:36619",
    requests_per_second="-1",
)
print(resp)
response = client.reindex_rethrottle(
  task_id: 'r1A2WoRbTwKZ516z6NEs5A:36619',
  requests_per_second: -1
)
puts response
res, err := es.ReindexRethrottle(
	"r1A2WoRbTwKZ516z6NEs5A:36619",
	esapi.IntPtr(-1),
)
fmt.Println(res, err)
const response = await client.reindexRethrottle({
  task_id: "r1A2WoRbTwKZ516z6NEs5A:36619",
  requests_per_second: "-1",
});
console.log(response);
POST _reindex/r1A2WoRbTwKZ516z6NEs5A:36619/_rethrottle?requests_per_second=-1

The task ID can be found using the tasks API.

Just like when setting it on the Reindex API, requests_per_second can be either -1 to disable throttling or any decimal number like 1.7 or 12 to throttle to that level. Rethrottling that speeds up the query takes effect immediately, but rethrottling that slows down the query will take effect after completing the current batch. This prevents scroll timeouts.

Slicing

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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.

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

Manual slicing
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Slice a reindex request manually by providing a slice id and total number of slices to each request:

resp = client.reindex(
    source={
        "index": "my-index-000001",
        "slice": {
            "id": 0,
            "max": 2
        }
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)

resp1 = client.reindex(
    source={
        "index": "my-index-000001",
        "slice": {
            "id": 1,
            "max": 2
        }
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp1)
response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001',
      slice: {
        id: 0,
        max: 2
      }
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response

response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001',
      slice: {
        id: 1,
        max: 2
      }
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: "my-index-000001",
    slice: {
      id: 0,
      max: 2,
    },
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);

const response1 = await client.reindex({
  source: {
    index: "my-index-000001",
    slice: {
      id: 1,
      max: 2,
    },
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response1);
POST _reindex
{
  "source": {
    "index": "my-index-000001",
    "slice": {
      "id": 0,
      "max": 2
    }
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}
POST _reindex
{
  "source": {
    "index": "my-index-000001",
    "slice": {
      "id": 1,
      "max": 2
    }
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

You can verify this works by:

resp = client.indices.refresh()
print(resp)

resp1 = client.search(
    index="my-new-index-000001",
    size="0",
    filter_path="hits.total",
)
print(resp1)
response = client.indices.refresh
puts response

response = client.search(
  index: 'my-new-index-000001',
  size: 0,
  filter_path: 'hits.total'
)
puts response
const response = await client.indices.refresh();
console.log(response);

const response1 = await client.search({
  index: "my-new-index-000001",
  size: 0,
  filter_path: "hits.total",
});
console.log(response1);
GET _refresh
POST my-new-index-000001/_search?size=0&filter_path=hits.total

which results in a sensible total like this one:

{
  "hits": {
    "total" : {
        "value": 120,
        "relation": "eq"
    }
  }
}
Automatic slicing
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You can also let _reindex automatically parallelize using Sliced scroll to slice on _id. Use slices to specify the number of slices to use:

resp = client.reindex(
    slices="5",
    refresh=True,
    source={
        "index": "my-index-000001"
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  slices: 5,
  refresh: true,
  body: {
    source: {
      index: 'my-index-000001'
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  slices: 5,
  refresh: "true",
  source: {
    index: "my-index-000001",
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex?slices=5&refresh
{
  "source": {
    "index": "my-index-000001"
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

You can also verify this works by:

resp = client.search(
    index="my-new-index-000001",
    size="0",
    filter_path="hits.total",
)
print(resp)
response = client.search(
  index: 'my-new-index-000001',
  size: 0,
  filter_path: 'hits.total'
)
puts response
const response = await client.search({
  index: "my-new-index-000001",
  size: 0,
  filter_path: "hits.total",
});
console.log(response);
POST my-new-index-000001/_search?size=0&filter_path=hits.total

which results in a sensible total like this one:

{
  "hits": {
    "total" : {
        "value": 120,
        "relation": "eq"
    }
  }
}

Setting slices to auto will let Elasticsearch choose 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.

Adding slices to _reindex just automates the manual process used in the section above, creating sub-requests which means it has some quirks:

  • You can see these requests in the Tasks APIs. 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 point above 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.
Picking the number of slices
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If slicing automatically, setting slices to auto will choose a reasonable number for most indices. If slicing manually or otherwise tuning automatic slicing, use these 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 (e.g. 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.

Reindex routing

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By default if _reindex sees a document with routing then the routing is preserved unless it’s changed by the script. You can set routing on the dest request to change this:

keep
Sets the routing on the bulk request sent for each match to the routing on the match. This is the default value.
discard
Sets the routing on the bulk request sent for each match to null.
=<some text>
Sets the routing on the bulk request sent for each match to all text after the =.

For example, you can use the following request to copy all documents from the source with the company name cat into the dest with routing set to cat.

$params = [
    'body' => [
        'source' => [
            'index' => 'source',
            'query' => [
                'match' => [
                    'company' => 'cat',
                ],
            ],
        ],
        'dest' => [
            'index' => 'dest',
            'routing' => '=cat',
        ],
    ],
];
$response = $client->reindex($params);
resp = client.reindex(
    source={
        "index": "source",
        "query": {
            "match": {
                "company": "cat"
            }
        }
    },
    dest={
        "index": "dest",
        "routing": "=cat"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'source',
      query: {
        match: {
          company: 'cat'
        }
      }
    },
    dest: {
      index: 'dest',
      routing: '=cat'
    }
  }
)
puts response
res, err := es.Reindex(
	strings.NewReader(`{
	  "source": {
	    "index": "source",
	    "query": {
	      "match": {
	        "company": "cat"
	      }
	    }
	  },
	  "dest": {
	    "index": "dest",
	    "routing": "=cat"
	  }
	}`))
fmt.Println(res, err)
const response = await client.reindex({
  source: {
    index: "source",
    query: {
      match: {
        company: "cat",
      },
    },
  },
  dest: {
    index: "dest",
    routing: "=cat",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "source",
    "query": {
      "match": {
        "company": "cat"
      }
    }
  },
  "dest": {
    "index": "dest",
    "routing": "=cat"
  }
}

By default _reindex uses scroll batches of 1000. You can change the batch size with the size field in the source element:

$params = [
    'body' => [
        'source' => [
            'index' => 'source',
            'size' => 100,
        ],
        'dest' => [
            'index' => 'dest',
            'routing' => '=cat',
        ],
    ],
];
$response = $client->reindex($params);
resp = client.reindex(
    source={
        "index": "source",
        "size": 100
    },
    dest={
        "index": "dest",
        "routing": "=cat"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'source',
      size: 100
    },
    dest: {
      index: 'dest',
      routing: '=cat'
    }
  }
)
puts response
res, err := es.Reindex(
	strings.NewReader(`{
	  "source": {
	    "index": "source",
	    "size": 100
	  },
	  "dest": {
	    "index": "dest",
	    "routing": "=cat"
	  }
	}`))
fmt.Println(res, err)
const response = await client.reindex({
  source: {
    index: "source",
    size: 100,
  },
  dest: {
    index: "dest",
    routing: "=cat",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "source",
    "size": 100
  },
  "dest": {
    "index": "dest",
    "routing": "=cat"
  }
}

Reindex with an ingest pipeline

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Reindex can also use the Ingest pipelines feature by specifying a pipeline like this:

$params = [
    'body' => [
        'source' => [
            'index' => 'source',
        ],
        'dest' => [
            'index' => 'dest',
            'pipeline' => 'some_ingest_pipeline',
        ],
    ],
];
$response = $client->reindex($params);
resp = client.reindex(
    source={
        "index": "source"
    },
    dest={
        "index": "dest",
        "pipeline": "some_ingest_pipeline"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'source'
    },
    dest: {
      index: 'dest',
      pipeline: 'some_ingest_pipeline'
    }
  }
)
puts response
res, err := es.Reindex(
	strings.NewReader(`{
	  "source": {
	    "index": "source"
	  },
	  "dest": {
	    "index": "dest",
	    "pipeline": "some_ingest_pipeline"
	  }
	}`))
fmt.Println(res, err)
const response = await client.reindex({
  source: {
    index: "source",
  },
  dest: {
    index: "dest",
    pipeline: "some_ingest_pipeline",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "source"
  },
  "dest": {
    "index": "dest",
    "pipeline": "some_ingest_pipeline"
  }
}

Query parameters

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refresh
(Optional, Boolean) If true, the request refreshes affected shards to make this operation visible to search. Defaults to false.
timeout

(Optional, time units) Period each indexing waits for the following operations:

Defaults to 1m (one minute). This guarantees Elasticsearch waits for at least the timeout before failing. The actual wait time could be longer, particularly when multiple waits occur.

wait_for_active_shards

(Optional, string) The number of copies of each shard that must be active before proceeding with the operation. Set to all or any non-negative integer up to the total number of copies of each shard in the index (number_of_replicas+1). Defaults to 1, meaning to wait just for each primary shard to be active.

See Active shards.

wait_for_completion
(Optional, Boolean) If true, the request blocks until the operation is complete. Defaults to true.
requests_per_second
(Optional, integer) The throttle for this request in sub-requests per second. Defaults to -1 (no throttle).
require_alias
(Optional, Boolean) If true, the destination must be an index alias. Defaults to false.
scroll
(Optional, time units) Specifies how long a consistent view of the index should be maintained for scrolled search.
slices
(Optional, integer) The number of slices this task should be divided into. Defaults to 1 meaning the task isn’t sliced into subtasks.
max_docs
(Optional, integer) Maximum number of documents to process. Defaults to all documents. When set to a value less then or equal to scroll_size then a scroll will not be used to retrieve the results for the operation.

Request body

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conflicts
(Optional, enum) Set to proceed to continue reindexing even if there are conflicts. Defaults to abort.
max_docs
(Optional, integer) The maximum number of documents to reindex. If conflicts is equal to proceed, reindex 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.
source
index
(Required, string) The name of the data stream, index, or alias you are copying from. Also accepts a comma-separated list to reindex from multiple sources.
query
(Optional, query object) Specifies the documents to reindex using the Query DSL.
remote
host
(Optional, string) The URL for the remote instance of Elasticsearch that you want to index from. Required when indexing from remote.
username
(Optional, string) The username to use for authentication with the remote host.
password
(Optional, string) The password to use for authentication with the remote host.
socket_timeout
(Optional, time units) The remote socket read timeout. Defaults to 30 seconds.
connect_timeout
(Optional, time units) The remote connection timeout. Defaults to 30 seconds.
headers
(Optional, object) An object containing the headers of ther request.
size
{Optional, integer) The number of documents to index per batch. Use when indexing from remote to ensure that the batches fit within the on-heap buffer, which defaults to a maximum size of 100 MB.
slice
id
(Optional, integer) Slice ID for manual slicing.
max
(Optional, integer) Total number of slices.
sort

(Optional, list) A comma-separated list of <field>:<direction> pairs to sort by before indexing. Use in conjunction with max_docs to control what documents are reindexed.

Deprecated in 7.6.

Sort in reindex is deprecated. Sorting in reindex was never guaranteed to index documents in order and prevents further development of reindex such as resilience and performance improvements. If used in combination with max_docs, consider using a query filter instead.

_source
(Optional, string) If true reindexes all source fields. Set to a list to reindex select fields. Defaults to true.
dest
index
(Required, string) The name of the data stream, index, or index alias you are copying to.
version_type
(Optional, enum) The versioning to use for the indexing operation. Valid values: internal, external, external_gt, external_gte. See Version types for more information.
op_type

(Optional, enum) Set to create to only index documents that do not already exist (put if absent). Valid values: index, create. Defaults to index.

To reindex to a data stream destination, this argument must be create.

pipeline
(Optional, string) the name of the pipeline to use.
script
source
(Optional, string) The script to run to update the document source or metadata when reindexing.
lang
(Optional, enum) The script language: painless, expression, mustache, java. For more information, see Scripting.

Response body

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took
(integer) The total milliseconds the entire operation took.
timed_out
{Boolean) This flag is set to true if any of the requests executed during the reindex timed out.
total
(integer) The number of documents that were successfully processed.
updated
(integer) The number of documents that were successfully updated, i.e. a document with same ID already existed prior to reindex updating it.
created
(integer) The number of documents that were successfully created.
deleted
(integer) The number of documents that were successfully deleted.
batches
(integer) The number of scroll responses pulled back by the reindex.
noops
(integer) The number of documents that were ignored because the script used for the reindex returned a noop value for ctx.op.
version_conflicts
(integer) The number of version conflicts that reindex hits.
retries
(integer) The number of retries attempted by reindex. bulk is the number of bulk actions retried and search is the number of search actions retried.
throttled_millis
(integer) Number of milliseconds the request slept to conform to requests_per_second.
requests_per_second
(integer) The number of requests per second effectively executed during the reindex.
throttled_until_millis
(integer) This field should always be equal to zero in a _reindex response. It only has meaning when using the Task API, where it indicates the next time (in milliseconds since epoch) a throttled request will be executed again in order to conform to requests_per_second.
failures
(array) Array of failures if there were any unrecoverable errors during the process. If this is non-empty then the request aborted because of those failures. Reindex is implemented using batches and any failure causes the entire process to abort but all failures in the current batch are collected into the array. You can use the conflicts option to prevent reindex from aborting on version conflicts.

Examples

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Reindex select documents with a query

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You can limit the documents by adding a query to the source. For example, the following request only copies documents with a user.id of kimchy into my-new-index-000001:

resp = client.reindex(
    source={
        "index": "my-index-000001",
        "query": {
            "term": {
                "user.id": "kimchy"
            }
        }
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001',
      query: {
        term: {
          'user.id' => 'kimchy'
        }
      }
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: "my-index-000001",
    query: {
      term: {
        "user.id": "kimchy",
      },
    },
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "my-index-000001",
    "query": {
      "term": {
        "user.id": "kimchy"
      }
    }
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

Reindex select documents with max_docs

edit

You can limit the number of processed documents by setting max_docs. For example, this request copies a single document from my-index-000001 to my-new-index-000001:

resp = client.reindex(
    max_docs=1,
    source={
        "index": "my-index-000001"
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    max_docs: 1,
    source: {
      index: 'my-index-000001'
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  max_docs: 1,
  source: {
    index: "my-index-000001",
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "max_docs": 1,
  "source": {
    "index": "my-index-000001"
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

Reindex from multiple sources

edit

The index attribute in source can be a list, allowing you to copy from lots of sources in one request. This will copy documents from the my-index-000001 and my-index-000002 indices:

resp = client.reindex(
    source={
        "index": [
            "my-index-000001",
            "my-index-000002"
        ]
    },
    dest={
        "index": "my-new-index-000002"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: [
        'my-index-000001',
        'my-index-000002'
      ]
    },
    dest: {
      index: 'my-new-index-000002'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: ["my-index-000001", "my-index-000002"],
  },
  dest: {
    index: "my-new-index-000002",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": ["my-index-000001", "my-index-000002"]
  },
  "dest": {
    "index": "my-new-index-000002"
  }
}

The Reindex API makes no effort to handle ID collisions so 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 using a script.

Reindex select fields with a source filter

edit

You can use source filtering to reindex a subset of the fields in the original documents. For example, the following request only reindexes the user.id and _doc fields of each document:

resp = client.reindex(
    source={
        "index": "my-index-000001",
        "_source": [
            "user.id",
            "_doc"
        ]
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001',
      _source: [
        'user.id',
        '_doc'
      ]
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: "my-index-000001",
    _source: ["user.id", "_doc"],
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "my-index-000001",
    "_source": ["user.id", "_doc"]
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

Reindex to change the name of a field

edit

_reindex can be used to build a copy of an index with renamed fields. Say you create an index containing documents that look like this:

resp = client.index(
    index="my-index-000001",
    id="1",
    refresh=True,
    document={
        "text": "words words",
        "flag": "foo"
    },
)
print(resp)
response = client.index(
  index: 'my-index-000001',
  id: 1,
  refresh: true,
  body: {
    text: 'words words',
    flag: 'foo'
  }
)
puts response
const response = await client.index({
  index: "my-index-000001",
  id: 1,
  refresh: "true",
  document: {
    text: "words words",
    flag: "foo",
  },
});
console.log(response);
POST my-index-000001/_doc/1?refresh
{
  "text": "words words",
  "flag": "foo"
}

but you don’t like the name flag and want to replace it with tag. _reindex can create the other index for you:

resp = client.reindex(
    source={
        "index": "my-index-000001"
    },
    dest={
        "index": "my-new-index-000001"
    },
    script={
        "source": "ctx._source.tag = ctx._source.remove(\"flag\")"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001'
    },
    dest: {
      index: 'my-new-index-000001'
    },
    script: {
      source: 'ctx._source.tag = ctx._source.remove("flag")'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: "my-index-000001",
  },
  dest: {
    index: "my-new-index-000001",
  },
  script: {
    source: 'ctx._source.tag = ctx._source.remove("flag")',
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "my-index-000001"
  },
  "dest": {
    "index": "my-new-index-000001"
  },
  "script": {
    "source": "ctx._source.tag = ctx._source.remove(\"flag\")"
  }
}

Now you can get the new document:

resp = client.get(
    index="my-new-index-000001",
    id="1",
)
print(resp)
response = client.get(
  index: 'my-new-index-000001',
  id: 1
)
puts response
const response = await client.get({
  index: "my-new-index-000001",
  id: 1,
});
console.log(response);
GET my-new-index-000001/_doc/1

which will return:

{
  "found": true,
  "_id": "1",
  "_index": "my-new-index-000001",
  "_version": 1,
  "_seq_no": 44,
  "_primary_term": 1,
  "_source": {
    "text": "words words",
    "tag": "foo"
  }
}

Reindex daily indices

edit

You can use _reindex in combination with Painless to reindex daily indices to apply a new template to the existing documents.

Assuming you have indices that contain documents like:

$params = [
    'index' => 'metricbeat-2016.05.30',
    'id' => '1',
    'body' => [
        'system.cpu.idle.pct' => 0.908,
    ],
];
$response = $client->index($params);
$params = [
    'index' => 'metricbeat-2016.05.31',
    'id' => '1',
    'body' => [
        'system.cpu.idle.pct' => 0.105,
    ],
];
$response = $client->index($params);
resp = client.index(
    index="metricbeat-2016.05.30",
    id="1",
    refresh=True,
    document={
        "system.cpu.idle.pct": 0.908
    },
)
print(resp)

resp1 = client.index(
    index="metricbeat-2016.05.31",
    id="1",
    refresh=True,
    document={
        "system.cpu.idle.pct": 0.105
    },
)
print(resp1)
response = client.index(
  index: 'metricbeat-2016.05.30',
  id: 1,
  refresh: true,
  body: {
    'system.cpu.idle.pct' => 0.908
  }
)
puts response

response = client.index(
  index: 'metricbeat-2016.05.31',
  id: 1,
  refresh: true,
  body: {
    'system.cpu.idle.pct' => 0.105
  }
)
puts response
{
	res, err := es.Index(
		"metricbeat-2016.05.30",
		strings.NewReader(`{
	  "system.cpu.idle.pct": 0.908
	}`),
		es.Index.WithDocumentID("1"),
		es.Index.WithRefresh("true"),
		es.Index.WithPretty(),
	)
	fmt.Println(res, err)
}

{
	res, err := es.Index(
		"metricbeat-2016.05.31",
		strings.NewReader(`{
	  "system.cpu.idle.pct": 0.105
	}`),
		es.Index.WithDocumentID("1"),
		es.Index.WithRefresh("true"),
		es.Index.WithPretty(),
	)
	fmt.Println(res, err)
}
const response = await client.index({
  index: "metricbeat-2016.05.30",
  id: 1,
  refresh: "true",
  document: {
    "system.cpu.idle.pct": 0.908,
  },
});
console.log(response);

const response1 = await client.index({
  index: "metricbeat-2016.05.31",
  id: 1,
  refresh: "true",
  document: {
    "system.cpu.idle.pct": 0.105,
  },
});
console.log(response1);
PUT metricbeat-2016.05.30/_doc/1?refresh
{"system.cpu.idle.pct": 0.908}
PUT metricbeat-2016.05.31/_doc/1?refresh
{"system.cpu.idle.pct": 0.105}

The new template for the metricbeat-* indices is already loaded into Elasticsearch, but it applies only to the newly created indices. Painless can be used to reindex the existing documents and apply the new template.

The script below extracts the date from the index name and creates a new index with -1 appended. All data from metricbeat-2016.05.31 will be reindexed into metricbeat-2016.05.31-1.

$params = [
    'body' => [
        'source' => [
            'index' => 'metricbeat-*',
        ],
        'dest' => [
            'index' => 'metricbeat',
        ],
        'script' => [
            'lang' => 'painless',
            'source' => 'ctx._index = \'metricbeat-\' + (ctx._index.substring(\'metricbeat-\'.length(), ctx._index.length())) + \'-1\'',
        ],
    ],
];
$response = $client->reindex($params);
resp = client.reindex(
    source={
        "index": "metricbeat-*"
    },
    dest={
        "index": "metricbeat"
    },
    script={
        "lang": "painless",
        "source": "ctx._index = 'metricbeat-' + (ctx._index.substring('metricbeat-'.length(), ctx._index.length())) + '-1'"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'metricbeat-*'
    },
    dest: {
      index: 'metricbeat'
    },
    script: {
      lang: 'painless',
      source: "ctx._index = 'metricbeat-' + (ctx._index.substring('metricbeat-'.length(), ctx._index.length())) + '-1'"
    }
  }
)
puts response
res, err := es.Reindex(
	strings.NewReader(`{
	  "source": {
	    "index": "metricbeat-*"
	  },
	  "dest": {
	    "index": "metricbeat"
	  },
	  "script": {
	    "lang": "painless",
	    "source": "ctx._index = 'metricbeat-' + (ctx._index.substring('metricbeat-'.length(), ctx._index.length())) + '-1'"
	  }
	}`))
fmt.Println(res, err)
const response = await client.reindex({
  source: {
    index: "metricbeat-*",
  },
  dest: {
    index: "metricbeat",
  },
  script: {
    lang: "painless",
    source:
      "ctx._index = 'metricbeat-' + (ctx._index.substring('metricbeat-'.length(), ctx._index.length())) + '-1'",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "metricbeat-*"
  },
  "dest": {
    "index": "metricbeat"
  },
  "script": {
    "lang": "painless",
    "source": "ctx._index = 'metricbeat-' + (ctx._index.substring('metricbeat-'.length(), ctx._index.length())) + '-1'"
  }
}

All documents from the previous metricbeat indices can now be found in the *-1 indices.

$params = [
    'index' => 'metricbeat-2016.05.30-1',
    'id' => '1',
];
$response = $client->get($params);
$params = [
    'index' => 'metricbeat-2016.05.31-1',
    'id' => '1',
];
$response = $client->get($params);
resp = client.get(
    index="metricbeat-2016.05.30-1",
    id="1",
)
print(resp)

resp1 = client.get(
    index="metricbeat-2016.05.31-1",
    id="1",
)
print(resp1)
response = client.get(
  index: 'metricbeat-2016.05.30-1',
  id: 1
)
puts response

response = client.get(
  index: 'metricbeat-2016.05.31-1',
  id: 1
)
puts response
{
	res, err := es.Get("metricbeat-2016.05.30-1", "1", es.Get.WithPretty())
	fmt.Println(res, err)
}

{
	res, err := es.Get("metricbeat-2016.05.31-1", "1", es.Get.WithPretty())
	fmt.Println(res, err)
}
const response = await client.get({
  index: "metricbeat-2016.05.30-1",
  id: 1,
});
console.log(response);

const response1 = await client.get({
  index: "metricbeat-2016.05.31-1",
  id: 1,
});
console.log(response1);
GET metricbeat-2016.05.30-1/_doc/1
GET metricbeat-2016.05.31-1/_doc/1

The previous method can also be used in conjunction with changing a field name to load only the existing data into the new index and rename any fields if needed.

Extract a random subset of the source

edit

_reindex can be used to extract a random subset of the source for testing:

resp = client.reindex(
    max_docs=10,
    source={
        "index": "my-index-000001",
        "query": {
            "function_score": {
                "random_score": {},
                "min_score": 0.9
            }
        }
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    max_docs: 10,
    source: {
      index: 'my-index-000001',
      query: {
        function_score: {
          random_score: {},
          min_score: 0.9
        }
      }
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  max_docs: 10,
  source: {
    index: "my-index-000001",
    query: {
      function_score: {
        random_score: {},
        min_score: 0.9,
      },
    },
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "max_docs": 10,
  "source": {
    "index": "my-index-000001",
    "query": {
      "function_score" : {
        "random_score" : {},
        "min_score" : 0.9    
      }
    }
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

You may need to adjust the min_score depending on the relative amount of data extracted from source.

Modify documents during reindexing

edit

Like _update_by_query, _reindex supports a script that modifies the document. Unlike _update_by_query, the script is allowed to modify the document’s metadata. This example bumps the version of the source document:

resp = client.reindex(
    source={
        "index": "my-index-000001"
    },
    dest={
        "index": "my-new-index-000001",
        "version_type": "external"
    },
    script={
        "source": "if (ctx._source.foo == 'bar') {ctx._version++; ctx._source.remove('foo')}",
        "lang": "painless"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      index: 'my-index-000001'
    },
    dest: {
      index: 'my-new-index-000001',
      version_type: 'external'
    },
    script: {
      source: "if (ctx._source.foo == 'bar') {ctx._version++; ctx._source.remove('foo')}",
      lang: 'painless'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    index: "my-index-000001",
  },
  dest: {
    index: "my-new-index-000001",
    version_type: "external",
  },
  script: {
    source:
      "if (ctx._source.foo == 'bar') {ctx._version++; ctx._source.remove('foo')}",
    lang: "painless",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "index": "my-index-000001"
  },
  "dest": {
    "index": "my-new-index-000001",
    "version_type": "external"
  },
  "script": {
    "source": "if (ctx._source.foo == 'bar') {ctx._version++; ctx._source.remove('foo')}",
    "lang": "painless"
  }
}

Just as in _update_by_query, you can set ctx.op to change the operation that is executed on the destination:

noop
Set ctx.op = "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.
delete
Set ctx.op = "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 request.

Reindex from remote

edit

Reindex supports reindexing from a remote Elasticsearch cluster:

resp = client.reindex(
    source={
        "remote": {
            "host": "http://otherhost:9200",
            "username": "user",
            "password": "pass"
        },
        "index": "my-index-000001",
        "query": {
            "match": {
                "test": "data"
            }
        }
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      remote: {
        host: 'http://otherhost:9200',
        username: 'user',
        password: 'pass'
      },
      index: 'my-index-000001',
      query: {
        match: {
          test: 'data'
        }
      }
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    remote: {
      host: "http://otherhost:9200",
      username: "user",
      password: "pass",
    },
    index: "my-index-000001",
    query: {
      match: {
        test: "data",
      },
    },
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "remote": {
      "host": "http://otherhost:9200",
      "username": "user",
      "password": "pass"
    },
    "index": "my-index-000001",
    "query": {
      "match": {
        "test": "data"
      }
    }
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

The host parameter must contain a scheme, host, port (e.g. https://otherhost:9200), and optional path (e.g. https://otherhost:9200/proxy). The username and password parameters are optional, and when they are present _reindex will connect to the remote Elasticsearch node using basic auth. Be sure to use https when using basic auth or the password will be sent in plain text. There are a range of settings available to configure the behaviour 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:

resp = client.reindex(
    source={
        "remote": {
            "host": "http://otherhost:9200",
            "headers": {
                "Authorization": "ApiKey API_KEY_VALUE"
            }
        },
        "index": "my-index-000001",
        "query": {
            "match": {
                "test": "data"
            }
        }
    },
    dest={
        "index": "my-new-index-000001"
    },
)
print(resp)
response = client.reindex(
  body: {
    source: {
      remote: {
        host: 'http://otherhost:9200',
        headers: {
          "Authorization": 'ApiKey API_KEY_VALUE'
        }
      },
      index: 'my-index-000001',
      query: {
        match: {
          test: 'data'
        }
      }
    },
    dest: {
      index: 'my-new-index-000001'
    }
  }
)
puts response
const response = await client.reindex({
  source: {
    remote: {
      host: "http://otherhost:9200",
      headers: {
        Authorization: "ApiKey API_KEY_VALUE",
      },
    },
    index: "my-index-000001",
    query: {
      match: {
        test: "data",
      },
    },
  },
  dest: {
    index: "my-new-index-000001",
  },
});
console.log(response);
POST _reindex
{
  "source": {
    "remote": {
      "host": "http://otherhost:9200",
      "headers": {
        "Authorization": "ApiKey API_KEY_VALUE"
      }
    },
    "index": "my-index-000001",
    "query": {
      "match": {
        "test": "data"
      }
    }
  },
  "dest": {
    "index": "my-new-index-000001"
  }
}

Remote hosts have to be explicitly allowed in elasticsearch.yml using the reindex.remote.whitelist property. 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 you are likely to find. This should allow you to upgrade from any version of Elasticsearch to the current version by reindexing from a cluster of the old version.

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.

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. The example below sets the batch size to 10 which is very, very small.

POST _reindex
{
  "source": {
    "remote": {
      "host": "http://otherhost:9200",
      ...
    },
    "index": "source",
    "size": 10,
    "query": {
      "match": {
        "test": "data"
      }
    }
  },
  "dest": {
    "index": "dest"
  }
}

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. This example sets the socket read timeout to one minute and the connection timeout to 10 seconds:

POST _reindex
{
  "source": {
    "remote": {
      "host": "http://otherhost:9200",
      ...,
      "socket_timeout": "1m",
      "connect_timeout": "10s"
    },
    "index": "source",
    "query": {
      "match": {
        "test": "data"
      }
    }
  },
  "dest": {
    "index": "dest"
  }
}

Configuring SSL parameters

edit

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.

The following settings are supported:

reindex.ssl.certificate_authorities
List of paths to PEM encoded certificate files that should be trusted. You cannot specify both reindex.ssl.certificate_authorities and reindex.ssl.truststore.path.
reindex.ssl.truststore.path
The path to the Java Keystore file that contains the certificates to trust. This keystore can be in "JKS" or "PKCS#12" format. You cannot specify both reindex.ssl.certificate_authorities and reindex.ssl.truststore.path.
reindex.ssl.truststore.password
The password to the truststore (reindex.ssl.truststore.path). [7.17.0] Deprecated in 7.17.0. Prefer reindex.ssl.truststore.secure_password instead. This setting cannot be used with reindex.ssl.truststore.secure_password.
reindex.ssl.truststore.secure_password (Secure)
The password to the truststore (reindex.ssl.truststore.path). This setting cannot be used with reindex.ssl.truststore.password.
reindex.ssl.truststore.type
The type of the truststore (reindex.ssl.truststore.path). Must be either jks or PKCS12. If the truststore path ends in ".p12", ".pfx" or "pkcs12", this setting defaults to PKCS12. Otherwise, it defaults to jks.
reindex.ssl.verification_mode
Indicates the type of verification to protect against man in the middle attacks and certificate forgery. One of full (verify the hostname and the certificate path), certificate (verify the certificate path, but not the hostname) or none (perform no verification - this is strongly discouraged in production environments). Defaults to full.
reindex.ssl.certificate
Specifies the path to the PEM encoded certificate (or certificate chain) to be used for HTTP client authentication (if required by the remote cluster) This setting requires that reindex.ssl.key also be set. You cannot specify both reindex.ssl.certificate and reindex.ssl.keystore.path.
reindex.ssl.key
Specifies the path to the PEM encoded private key associated with the certificate used for client authentication (reindex.ssl.certificate). You cannot specify both reindex.ssl.key and reindex.ssl.keystore.path.
reindex.ssl.key_passphrase
Specifies the passphrase to decrypt the PEM encoded private key (reindex.ssl.key) if it is encrypted. [7.17.0] Deprecated in 7.17.0. Prefer reindex.ssl.secure_key_passphrase instead. Cannot be used with reindex.ssl.secure_key_passphrase.
reindex.ssl.secure_key_passphrase (Secure)
Specifies the passphrase to decrypt the PEM encoded private key (reindex.ssl.key) if it is encrypted. Cannot be used with reindex.ssl.key_passphrase.
reindex.ssl.keystore.path
Specifies the path to the keystore that contains a private key and certificate to be used for HTTP client authentication (if required by the remote cluster). This keystore can be in "JKS" or "PKCS#12" format. You cannot specify both reindex.ssl.key and reindex.ssl.keystore.path.
reindex.ssl.keystore.type
The type of the keystore (reindex.ssl.keystore.path). Must be either jks or PKCS12. If the keystore path ends in ".p12", ".pfx" or "pkcs12", this setting defaults to PKCS12. Otherwise, it defaults to jks.
reindex.ssl.keystore.password
The password to the keystore (reindex.ssl.keystore.path). [7.17.0] Deprecated in 7.17.0. Prefer reindex.ssl.keystore.secure_password instead. This setting cannot be used with reindex.ssl.keystore.secure_password.
reindex.ssl.keystore.secure_password (Secure)
The password to the keystore (reindex.ssl.keystore.path). This setting cannot be used with reindex.ssl.keystore.password.
reindex.ssl.keystore.key_password
The password for the key in the keystore (reindex.ssl.keystore.path). Defaults to the keystore password. [7.17.0] Deprecated in 7.17.0. Prefer reindex.ssl.keystore.secure_key_password instead. This setting cannot be used with reindex.ssl.keystore.secure_key_password.
reindex.ssl.keystore.secure_key_password (Secure)
The password for the key in the keystore (reindex.ssl.keystore.path). Defaults to the keystore password. This setting cannot be used with reindex.ssl.keystore.key_password.
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