Searching Across Multiple Elasticsearch Indices

This note describes how to search over multiple indices in Elasticsearch.

Takahiro Iwasa

2020-12-31

2 min read

This note describes how to search over multiple indices in Elasticsearch.

Launching Elasticsearch

Below is an example docker-compose.yml file to configure and start the cluster.

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version: '3'
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services:
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  elasticsearch:
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    image: elasticsearch:7.10.1
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    container_name: elasticsearch
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    environment:
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      - discovery.type=single-node
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      - bootstrap.memory_lock=true
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    ports:
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      - 9200:9200

Start the cluster using the following command:

docker-compose up -d

Preparing Data

To experiment with multiple indices, index some data into users-2020-11 and users-2020-12 using the curl command:

curl -X POST -H 'Content-Type: application/json' -d '{"name": "hoge"}' localhost:9200/users-2020-11/_doc/
curl -X POST -H 'Content-Type: application/json' -d '{"name": "fuga"}' localhost:9200/users-2020-12/_doc/

Searching Data

Searching with Wildcards

You can query data from multiple indices using a wildcard expression. For example:

curl localhost:9200/users-2020-*/_search | jq .hits.hits

The response will contain data from both users-2020-11 and users-2020-12:

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[
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  {
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    "_index": "users-2020-11",
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    "_type": "_doc",
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    "_id": "PNQ3tXYBKT-fwQ71grcz",
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    "_score": 1,
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    "_source": {
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      "name": "hoge"
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    }
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  },
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  {
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    "_index": "users-2020-12",
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    "_type": "_doc",
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    "_id": "PdQ3tXYBKT-fwQ71p7cy",
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    "_score": 1,
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    "_source": {
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      "name": "fuga"
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    }
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  }
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]

Searching with CSV Format

Another way to search is by specifying multiple indices as a comma-separated list:

🔥 Caution

Ensure that your URL length does not exceed the maximum limit when using this approach.

curl localhost:9200/users-2020-11,users-2020-12/_search | jq .hits.hits

The response will contain data from both users-2020-11 and users-2020-12:

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[
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  {
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    "_index": "users-2020-11",
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    "_type": "_doc",
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    "_id": "PNQ3tXYBKT-fwQ71grcz",
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    "_score": 1,
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    "_source": {
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      "name": "hoge"
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    }
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  },
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  {
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    "_index": "users-2020-12",
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    "_type": "_doc",
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    "_id": "PdQ3tXYBKT-fwQ71p7cy",
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    "_score": 1,
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    "_source": {
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      "name": "fuga"
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    }
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  }
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]