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_ttl field
edit_ttl
field
editDeprecated in 2.0.0-beta2.
The current _ttl
implementation is deprecated and will be replaced with a different implementation in a future version
Some types of documents, such as session data or special offers, come with an
expiration date. The _ttl
field allows you to specify the minimum time a
document should live, after which time the document is deleted automatically.
Prefer index-per-timeframe to TTL
With TTL , expired documents first have to be marked as deleted then later purged from the index when segments are merged. For append-only time-based data such as log events, it is much more efficient to use an index-per-day / week / month instead of TTLs. Old log data can be removed by simply deleting old indices.
The _ttl
field may be enabled as follows:
PUT my_index { "mappings": { "my_type": { "_ttl": { "enabled": true } } } } PUT my_index/my_type/1?ttl=10m { "text": "Will expire in 10 minutes" } PUT my_index/my_type/2 { "text": "Will not expire" }
This document will expire 10 minutes after being indexed. |
|
This document has no TTL set and will not expire. |
The expiry time is calculated as the value of the
_timestamp
field (or now()
if the _timestamp
is not enabled) plus the ttl
specified in the indexing request.
Default TTL
editYou can provide a default _ttl
, which will be applied to indexing requests where the ttl
is not specified:
PUT my_index { "mappings": { "my_type": { "_ttl": { "enabled": true, "default": "5m" } } } } PUT my_index/my_type/1?ttl=10m { "text": "Will expire in 10 minutes" } PUT my_index/my_type/2 { "text": "Will expire in 5 minutes" }
This document will expire 10 minutes after being indexed. |
|
This document has no TTL set and so will expire after the default 5 minutes. |
The default
value can use time units like d
for days, and
will use ms
as the default unit if no time unit is provided.
You can dynamically update the default
value using the put mapping
API. It won’t change the _ttl
of already indexed documents but will be
used for future documents.
Note on documents expiration
editExpired documents will be automatically deleted periodically. The following settings control the expiry process:
-
indices.ttl.interval
-
How often the purge process should run. Defaults to
60s
. Expired documents may still be retrieved before they are purged. -
indices.ttl.bulk_size
-
How many deletions are handled by a single
bulk
request. The default value is10000
.
Note on detect_noop
editIf an update tries to update just the _ttl
without changing the _source
of
the document it’s expiration time won’t be updated if detect_noop
is true
.
In 2.1 detect_noop
defaults to true
.