Rollover Index
editRollover Index
editThe rollover index API rolls an alias to a new index when the existing index meets a condition you provide. You can use this API to retire an index that becomes too large or too old.
To roll over an index, a condition must be met when you call the API. Elasticsearch does not monitor the index after you receive an API response. To automatically roll over indices when a condition is met, you can use Elasticsearch’s index lifecycle management (ILM) policies.
The API accepts a single alias name and a list of conditions
. The alias must point to a write index for
a Rollover request to be valid. There are two ways this can be achieved, and depending on the configuration, the
alias metadata will be updated differently. The two scenarios are as follows:
-
The alias only points to a single index with
is_write_index
not configured (defaults tonull
).
In this scenario, the original index will have their rollover alias will be added to the newly created index, and removed from the original (rolled-over) index.
-
The alias points to one or more indices with
is_write_index
set totrue
on the index to be rolled over (the write index).
In this scenario, the write index will have its rollover alias' is_write_index
set to false
, while the newly created index
will now have the rollover alias pointing to it as the write index with is_write_index
as true
.
The available conditions are:
Table 30. conditions
parameters
Name | Description |
---|---|
max_age |
The maximum age of the index |
max_docs |
The maximum number of documents the index should contain. This does not add documents multiple times for replicas |
max_size |
The maximum estimated size of the primary shard of the index |
PUT /logs-000001 { "aliases": { "logs_write": {} } } # Add > 1000 documents to logs-000001 POST /logs_write/_rollover { "conditions": { "max_age": "7d", "max_docs": 1000, "max_size": "5gb" } }
Creates an index called |
|
If the index pointed to by |
The above request might return the following response:
{ "acknowledged": true, "shards_acknowledged": true, "old_index": "logs-000001", "new_index": "logs-000002", "rolled_over": true, "dry_run": false, "conditions": { "[max_age: 7d]": false, "[max_docs: 1000]": true, "[max_size: 5gb]": false, } }
Naming the new index
editIf the name of the existing index ends with -
and a number — e.g.
logs-000001
— then the name of the new index will follow the same pattern,
incrementing the number (logs-000002
). The number is zero-padded with a length
of 6, regardless of the old index name.
If the old name doesn’t match this pattern then you must specify the name for the new index as follows:
POST /my_alias/_rollover/my_new_index_name { "conditions": { "max_age": "7d", "max_docs": 1000, "max_size": "5gb" } }
Using date math with the rollover API
editIt can be useful to use date math to name the
rollover index according to the date that the index rolled over, e.g.
logstash-2016.02.03
. The rollover API supports date math, but requires the
index name to end with a dash followed by a number, e.g.
logstash-2016.02.03-1
which is incremented every time the index is rolled
over. For instance:
# PUT /<logs-{now/d}-1> with URI encoding: PUT /%3Clogs-%7Bnow%2Fd%7D-1%3E { "aliases": { "logs_write": {} } } PUT logs_write/_doc/1 { "message": "a dummy log" } POST logs_write/_refresh # Wait for a day to pass POST /logs_write/_rollover { "conditions": { "max_docs": "1" } }
Creates an index named with today’s date (e.g.) |
|
Rolls over to a new index with today’s date, e.g. |
These indices can then be referenced as described in the date math documentation. For example, to search over indices created in the last three days, you could do the following:
# GET /<logs-{now/d}-*>,<logs-{now/d-1d}-*>,<logs-{now/d-2d}-*>/_search GET /%3Clogs-%7Bnow%2Fd%7D-*%3E%2C%3Clogs-%7Bnow%2Fd-1d%7D-*%3E%2C%3Clogs-%7Bnow%2Fd-2d%7D-*%3E/_search
Defining the new index
editThe settings, mappings, and aliases for the new index are taken from any
matching index templates. Additionally, you can specify
settings
, mappings
, and aliases
in the body of the request, just like the
create index API. Values specified in the request
override any values set in matching index templates. For example, the following
rollover
request overrides the index.number_of_shards
setting:
PUT /logs-000001 { "aliases": { "logs_write": {} } } POST /logs_write/_rollover { "conditions" : { "max_age": "7d", "max_docs": 1000, "max_size": "5gb" }, "settings": { "index.number_of_shards": 2 } }
Dry run
editThe rollover API supports dry_run
mode, where request conditions can be
checked without performing the actual rollover:
PUT /logs-000001 { "aliases": { "logs_write": {} } } POST /logs_write/_rollover?dry_run { "conditions" : { "max_age": "7d", "max_docs": 1000, "max_size": "5gb" } }
Wait For Active Shards
editBecause the rollover operation creates a new index to rollover to, the
wait_for_active_shards
setting on
index creation applies to the rollover action as well.
Write Index Alias Behavior
editThe rollover alias when rolling over a write index that has is_write_index
explicitly set to true
is not
swapped during rollover actions. Since having an alias point to multiple indices is ambiguous in distinguishing
which is the correct write index to roll over, it is not valid to rollover an alias that points to multiple indices.
For this reason, the default behavior is to swap which index is being pointed to by the write-oriented alias. This
was logs_write
in some of the above examples. Since setting is_write_index
enables an alias to point to multiple indices
while also being explicit as to which is the write index that rollover should target, removing the alias from the rolled over
index is not necessary. This simplifies things by allowing for one alias to behave both as the write and read aliases for
indices that are being managed with Rollover.
Look at the behavior of the aliases in the following example where is_write_index
is set on the rolled over index.
PUT my_logs_index-000001 { "aliases": { "logs": { "is_write_index": true } } } PUT logs/_doc/1 { "message": "a dummy log" } POST logs/_refresh POST /logs/_rollover { "conditions": { "max_docs": "1" } } PUT logs/_doc/2 { "message": "a newer log" }
configures |
|
newly indexed documents against the |
{ "_index" : "my_logs_index-000002", "_type" : "_doc", "_id" : "2", "_version" : 1, "result" : "created", "_shards" : { "total" : 2, "successful" : 1, "failed" : 0 }, "_seq_no" : 0, "_primary_term" : 1 }
After the rollover, the alias metadata for the two indices will have the is_write_index
setting
reflect each index’s role, with the newly created index as the write index.
{ "my_logs_index-000002": { "aliases": { "logs": { "is_write_index": true } } }, "my_logs_index-000001": { "aliases": { "logs": { "is_write_index" : false } } } }