Warmers

Index warming allows to run registered search requests to warm up the index before it is available for search. With the near real time aspect of search, cold data (segments) will be warmed up before they become available for search. This also means that warmer queries will be run automatically on node startup given that the segments will be cold then. This includes things such as the filter cache, filesystem cache, and loading field data for fields.

Warmup searches typically include requests that require heavy loading of data, such as aggregations or sorting on specific fields. The warmup APIs allows to register warmup (search) under specific names, remove them, and get them.

Index warmup can be disabled by setting index.warmer.enabled to false. It is supported as a realtime setting using update settings API. This can be handy when doing initial bulk indexing: disable pre registered warmers to make indexing faster and less expensive and then enable it.

Warmers can be registered when an index gets created, for example:

curl -XPUT localhost:9200/test -d '{
    "warmers" : {
        "warmer_1" : {
            "types" : [],
            "source" : {
                "query" : {
                    ...
                },
                "aggs" : {
                    ...
                }
            }
        }
    }
}'

Or, in an index template:

curl -XPUT localhost:9200/_template/template_1 -d '
{
    "template" : "te*",
    "warmers" : {
        "warmer_1" : {
            "types" : [],
            "source" : {
                "query" : {
                    ...
                },
                "aggs" : {
                    ...
                }
            }
        }
    }
}'

Allows to put a warmup search request on a specific index (or indices), with the body composing of a regular search request. Types can be provided as part of the URI if the search request is designed to be run only against the specific types.

Here is an example that registers a warmup called warmer_1 against index test (can be alias or several indices), for a search request that runs against all types:

curl -XPUT localhost:9200/test/_warmer/warmer_1 -d '{
    "query" : {
        "match_all" : {}
    },
    "aggs" : {
        "aggs_1" : {
            "terms" : {
                "field" : "field"
            }
        }
    }
}'

And an example that registers a warmup against specific types:

curl -XPUT localhost:9200/test/type1/_warmer/warmer_1 -d '{
    "query" : {
        "match_all" : {}
    },
    "aggs" : {
        "aggs_1" : {
            "terms" : {
                "field" : "field"
            }
        }
    }
}'

All options:

PUT _warmer/{warmer_name}

PUT /{index}/_warmer/{warmer_name}

PUT /{index}/{type}/_warmer/{warmer_name}

where

Instead of _warmer you can also use the plural _warmers.

Warmers can be deleted using the following endpoint:

[DELETE] /{index}/_warmer/{name}

where

Instead of _warmer you can also use the plural _warmers.

Getting a warmer for specific index (or alias, or several indices) based on its name. The provided name can be a simple wildcard expression or omitted to get all warmers. Some examples:

# get warmer named warmer_1 on test index
curl -XGET localhost:9200/test/_warmer/warmer_1

# get all warmers that start with warm on test index
curl -XGET localhost:9200/test/_warmer/warm*

# get all warmers for test index
curl -XGET localhost:9200/test/_warmer/