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Reindex API
editReindex API
editReindex does not attempt to set up the destination index. It does
not copy the settings of the source index. You should set up the destination
index prior to running a _reindex
action, including setting up mappings, shard
counts, replicas, etc.
The most basic form of _reindex
just copies documents from one index to another.
This will copy documents from the twitter
index into the new_twitter
index:
POST _reindex { "source": { "index": "twitter" }, "dest": { "index": "new_twitter" } }
That will return something like this:
{ "took" : 147, "timed_out": false, "created": 120, "updated": 0, "deleted": 0, "batches": 1, "version_conflicts": 0, "noops": 0, "retries": { "bulk": 0, "search": 0 }, "throttled_millis": 0, "requests_per_second": -1.0, "throttled_until_millis": 0, "total": 120, "failures" : [ ] }
Just like _update_by_query
, _reindex
gets a
snapshot of the source index but its target must be a different index so
version conflicts are unlikely. The dest
element can be configured like the
index API to control optimistic concurrency control. Just leaving out
version_type
(as above) or setting it to internal
will cause Elasticsearch
to blindly dump documents into the target, overwriting any that happen to have
the same type and id:
POST _reindex { "source": { "index": "twitter" }, "dest": { "index": "new_twitter", "version_type": "internal" } }
Setting version_type
to external
will cause 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 index than they do
in the source index:
POST _reindex { "source": { "index": "twitter" }, "dest": { "index": "new_twitter", "version_type": "external" } }
Settings op_type
to create
will cause _reindex
to only create missing
documents in the target index. All existing documents will cause a version
conflict:
POST _reindex { "source": { "index": "twitter" }, "dest": { "index": "new_twitter", "op_type": "create" } }
By default version conflicts abort the _reindex
process but you can just
count them by settings "conflicts": "proceed"
in the request body:
POST _reindex { "conflicts": "proceed", "source": { "index": "twitter" }, "dest": { "index": "new_twitter", "op_type": "create" } }
You can limit the documents by adding a type to the source
or by adding a
query. This will only copy tweet
's made by kimchy
into new_twitter
:
POST _reindex { "source": { "index": "twitter", "type": "tweet", "query": { "term": { "user": "kimchy" } } }, "dest": { "index": "new_twitter" } }
index
and type
in source
can both be lists, allowing you to copy from
lots of sources in one request. This will copy documents from the tweet
and
post
types in the twitter
and blog
index. It’d include the post
type in
the twitter
index and the tweet
type in the blog
index. If you want to be
more specific you’ll need to use the query
. It also makes no effort to handle
ID collisions. The target index will remain valid but it’s not easy to predict
which document will survive because the iteration order isn’t well defined.
POST _reindex { "source": { "index": ["twitter", "blog"], "type": ["tweet", "post"] }, "dest": { "index": "all_together" } }
It’s also possible to limit the number of processed documents by setting
size
. This will only copy a single document from twitter
to
new_twitter
:
POST _reindex { "size": 1, "source": { "index": "twitter" }, "dest": { "index": "new_twitter" } }
If you want a particular set of documents from the twitter index you’ll
need to sort. Sorting makes the scroll less efficient but in some contexts
it’s worth it. If possible, prefer a more selective query to size
and sort
.
This will copy 10000 documents from twitter
into new_twitter
:
POST _reindex { "size": 10000, "source": { "index": "twitter", "sort": { "date": "desc" } }, "dest": { "index": "new_twitter" } }
The source
section supports all the elements that are supported in a
search request. For instance only a subset of the
fields from the original documents can be reindexed using source filtering
as follows:
POST _reindex { "source": { "index": "twitter", "_source": ["user", "tweet"] }, "dest": { "index": "new_twitter" } }
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:
POST _reindex { "source": { "index": "twitter" }, "dest": { "index": "new_twitter", "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 index:
-
noop
-
Set
ctx.op = "noop"
if your script decides that the document doesn’t have to be indexed in the destination index. This no operation will be reported in thenoop
counter in the response body. -
delete
-
Set
ctx.op = "delete"
if your script decides that the document must be deleted from the destination index. The deletion will be reported in thedeleted
counter in the response body.
Setting ctx.op
to anything else is an error. Setting any
other field in ctx
is an error.
Think of the possibilities! Just be careful! With great power…. You can change:
-
_id
-
_type
-
_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 that document to be
overwritten in the target index regardless of the version on the target or the
version type you use in the _reindex
request.
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. The default.
-
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
index with the company name cat
into the dest
index with
routing set to cat
.
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:
POST _reindex { "source": { "index": "source", "size": 100 }, "dest": { "index": "dest", "routing": "=cat" } }
Reindex can also use the Ingest Node feature by specifying a
pipeline
like this:
POST _reindex { "source": { "index": "source" }, "dest": { "index": "dest", "pipeline": "some_ingest_pipeline" } }
Reindex from Remote
editReindex supports reindexing from a remote Elasticsearch cluster:
POST _reindex { "source": { "remote": { "host": "http://otherhost:9200", "username": "user", "password": "pass" }, "index": "source", "query": { "match": { "test": "data" } } }, "dest": { "index": "dest" } }
The host
parameter must contain a scheme, host, and port (e.g.
https://otherhost:9200
). 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.
Remote hosts have to be explicitly whitelisted in elasticsearch.yaml using the
reindex.remote.whitelist
property. It can be set to a comma delimited list
of allowed remote host
and port
combinations (e.g.
otherhost:9200, another:9200, 127.0.10.*:9200, localhost:*
). Scheme is
ignored by the whitelist - only host and port are used.
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.
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 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 thirty seconds. This example
sets the socket read timeout to one minute and the connection timeout to ten
seconds:
POST _reindex { "source": { "remote": { "host": "http://otherhost:9200", "socket_timeout": "1m", "connect_timeout": "10s" }, "index": "source", "query": { "match": { "test": "data" } } }, "dest": { "index": "dest" } }
URL Parameters
editIn addition to the standard parameters like pretty
, the Reindex API also
supports refresh
, wait_for_completion
, wait_for_active_shards
, timeout
, and
requests_per_second
.
Sending the refresh
url parameter will cause all indexes to which the request
wrote to be refreshed. This is different than the Index API’s refresh
parameter which causes just the shard that received the new data to be refreshed.
If the request contains wait_for_completion=false
then Elasticsearch will
perform some preflight checks, launch the request, and then return a task
which can be used with Tasks APIs
to cancel or get the status of the task. Elasticsearch will also create a
record of this task as a document at .tasks/task/${taskId}
. This is yours
to keep or remove as you see fit. When you are done with it, delete it so
Elasticsearch can reclaim the space it uses.
wait_for_active_shards
controls how many copies of a shard must be active
before proceeding with the reindexing. See here
for details. timeout
controls how long each write request waits for unavailable
shards to become available. Both work exactly how they work in the
Bulk API.
requests_per_second
can be set to any positive decimal number (1.4
, 6
,
1000
, etc) and throttles rate at which reindex issues batches of index
operations by padding each batch with a wait time. The throttling can be
disabled by setting requests_per_second
to -1
.
The throttling is done by waiting between batches so that 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 the 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 will
cause Elasticsearch to create many requests and then wait for a while before
starting the next set. This is "bursty" instead of "smooth". The default is -1
.
Response body
editThe JSON response looks like this:
{ "took": 639, "timed_out": false, "total": 5, "updated": 0, "created": 5, "deleted": 0, "batches": 1, "noops": 0, "version_conflicts": 2, "retries": { "bulk": 0, "search": 0 }, "throttled_millis": 0, "requests_per_second": 1, "throttled_until_millis": 0, "failures": [ ] }
-
took
- The number of milliseconds from start to end of the whole operation.
-
timed_out
-
This flag is set to
true
if any of the requests executed during the reindex has timed out. -
total
- The number of documents that were successfully processed.
-
updated
- The number of documents that were successfully updated.
-
created
- The number of documents that were successfully created.
-
deleted
- The number of documents that were successfully deleted.
-
batches
- The number of scroll responses pulled back by the reindex.
-
noops
-
The number of documents that were ignored because the script used for
the reindex returned a
noop
value forctx.op
. -
version_conflicts
- The number of version conflicts that reindex hit.
-
retries
-
The number of retries attempted by reindex.
bulk
is the number of bulk actions retried andsearch
is the number of search actions retried. -
throttled_millis
-
Number of milliseconds the request slept to conform to
requests_per_second
. -
requests_per_second
- The number of requests per second effectively executed during the reindex.
-
throttled_until_millis
-
This field should always be equal to zero in a delete by query 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 of all indexing failures. If this is non-empty then the request aborted
because of those failures. See
conflicts
for how to prevent version conflicts from aborting the operation.
Works with the Task API
editYou can fetch the status of all running reindex requests with the Task API:
GET _tasks?detailed=true&actions=*reindex
The responses looks like:
{ "nodes" : { "r1A2WoRbTwKZ516z6NEs5A" : { "name" : "r1A2WoR", "transport_address" : "127.0.0.1:9300", "host" : "127.0.0.1", "ip" : "127.0.0.1:9300", "attributes" : { "testattr" : "test", "portsfile" : "true" }, "tasks" : { "r1A2WoRbTwKZ516z6NEs5A:36619" : { "node" : "r1A2WoRbTwKZ516z6NEs5A", "id" : 36619, "type" : "transport", "action" : "indices:data/write/reindex", "status" : { "total" : 6154, "updated" : 3500, "created" : 0, "deleted" : 0, "batches" : 4, "version_conflicts" : 0, "noops" : 0, "retries": { "bulk": 0, "search": 0 }, "throttled_millis": 0 }, "description" : "" } } } } }
this object contains the actual status. It is just like the response json
with the important addition of the |
With the task id you can look up the task directly:
GET /_tasks/taskId:1
The advantage of this API is that it integrates with wait_for_completion=false
to transparently return the status of completed tasks. If the task is completed
and wait_for_completion=false
was set on it them it’ll come back with a
results
or an error
field. The cost of this feature is the document that
wait_for_completion=false
creates at .tasks/task/${taskId}
. It is up to
you to delete that document.
Works with the Cancel Task API
editAny Reindex can be canceled using the Task Cancel API:
POST _tasks/task_id:1/_cancel
The task_id
can be found using the tasks API above.
Cancelation should happen quickly but might take a few seconds. The task status API above will continue to list the task until it is wakes to cancel itself.
Rethrottling
editThe value of requests_per_second
can be changed on a running reindex using
the _rethrottle
API:
POST _reindex/task_id:1/_rethrottle?requests_per_second=-1
The task_id
can be found using the tasks API above.
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 rethrotting that slows down the query will
take effect on after completing the current batch. This prevents scroll
timeouts.
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:
POST test/test/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:
POST _reindex { "source": { "index": "test" }, "dest": { "index": "test2" }, "script": { "source": "ctx._source.tag = ctx._source.remove(\"flag\")" } }
Now you can get the new document:
GET test2/test/1
and it’ll look like:
{ "found": true, "_id": "1", "_index": "test2", "_type": "test", "_version": 1, "_source": { "text": "words words", "tag": "foo" } }
Or you can search by tag
or whatever you want.
Slicing
editReindex 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.
Manual slicing
editSlice a reindex request manually by providing a slice id and total number of slices to each request:
POST _reindex { "source": { "index": "twitter", "slice": { "id": 0, "max": 2 } }, "dest": { "index": "new_twitter" } } POST _reindex { "source": { "index": "twitter", "slice": { "id": 1, "max": 2 } }, "dest": { "index": "new_twitter" } }
Which you can verify works with:
GET _refresh POST new_twitter/_search?size=0&filter_path=hits.total
Which results in a sensible total
like this one:
{ "hits": { "total": 120 } }
Automatic slicing
editYou can also let reindex automatically parallelize using Sliced Scroll to
slice on _uid
. Use slices
to specify the number of slices to use:
POST _reindex?slices=5&refresh { "source": { "index": "twitter" }, "dest": { "index": "new_twitter" } }
Which you also can verify works with:
POST new_twitter/_search?size=0&filter_path=hits.total
Which results in a sensible total
like this one:
{ "hits": { "total": 120 } }
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 source indices, it will choose the number of slices based
on the 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
andsize
on a request withslices
are distributed proportionally to each sub-request. Combine that with the point above about distribution being uneven and you should conclude that the usingsize
withslices
might not result in exactlysize
documents being `_reindex`ed. - Each sub-requests gets a slightly different snapshot of the source index though these are all taken at approximately the same time.
Picking the number of slices
editIf slicing automatically, setting slices
to auto
will choose a reasonable
number for most indices. If you’re 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, (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.
Reindex daily indices
editYou can use _reindex
in combination with Painless
to reindex daily indices to apply a new template to the existing documents.
Assuming you have indices consisting of documents as following:
PUT metricbeat-2016.05.30/beat/1?refresh {"system.cpu.idle.pct": 0.908} PUT metricbeat-2016.05.31/beat/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 reindex
into metricbeat-2016.05.31-1
.
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 now can be found in the *-1
indices.
GET metricbeat-2016.05.30-1/beat/1 GET metricbeat-2016.05.31-1/beat/1
The previous method can also be used in combination with change the name of a field to only load the existing data into the new index, but also rename fields if needed.
Extracting a random subset of an index
editReindex can be used to extract a random subset of an index for testing: