Free and Open, Distributed, RESTful Search Engine
= Elasticsearch
== A Distributed RESTful Search Engine
=== https://www.elastic.co/products/elasticsearch[https://www.elastic.co/products/elasticsearch]
Elasticsearch is a distributed RESTful search engine built for the cloud. Features include:
== Getting Started
First of all, DON'T PANIC. It will take 5 minutes to get the gist of what Elasticsearch is all about.
=== Installation
bin/elasticsearchon Linux or macOS. Run
bin\elasticsearch.baton Windows.
curl -X GET http://localhost:9200/to verify Elasticsearch is running.
=== Indexing
First, index some sample JSON documents. The first request automatically creates the
my-index-000001index.
curl -X POST 'http://localhost:9200/my-index-000001/_doc?pretty' -H 'Content-Type: application/json' -d ' { "@timestamp": "2099-11-15T13:12:00", "message": "GET /search HTTP/1.1 200 1070000", "user": { "id": "kimchy" } }'
curl -X POST 'http://localhost:9200/my-index-000001/_doc?pretty' -H 'Content-Type: application/json' -d ' { "@timestamp": "2099-11-15T14:12:12", "message": "GET /search HTTP/1.1 200 1070000", "user": { "id": "elkbee" } }'
curl -X POST 'http://localhost:9200/my-index-000001/_doc?pretty' -H 'Content-Type: application/json' -d ' { "@timestamp": "2099-11-15T01:46:38", "message": "GET /search HTTP/1.1 200 1070000", "user": { "id": "elkbee" }
=== Search
Next, use a search request to find any documents with a
user.idof
kimchy.
Instead of a query string, you can use Elasticsearch's https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl.html[Query DSL] in the request body.
curl -X GET 'http://localhost:9200/my-index-000001/_search?pretty=true' -H 'Content-Type: application/json' -d ' { "query" : { "match" : { "user.id": "kimchy" } }
You can also retrieve all documents in
my-index-000001.
curl -X GET 'http://localhost:9200/my-index-000001/search?pretty=true' -H 'Content-Type: application/json' -d ' { "query" : { "matchall" : {} }
During indexing, Elasticsearch automatically mapped the
@timestampfield as a date. This lets you run a range search.
curl -X GET 'http://localhost:9200/my-index-000001/_search?pretty=true' -H 'Content-Type: application/json' -d ' { "query" : { "range" : { "@timestamp": { "from": "2099-11-15T13:00:00", "to": "2099-11-15T14:00:00" } } }
=== Multiple indices
Elasticsearch supports multiple indices. The previous examples used an index called
my-index-000001. You can create another index,
my-index-000002, to store additional data when
my-index-000001reaches a certain age or size. You can also use separate indices to store different types of data.
You can configure each index differently. The following request creates
my-index-000002with two primary shards rather than the default of one. This may be helpful for larger indices.
curl -X PUT 'http://localhost:9200/my-index-000002?pretty' -H 'Content-Type: application/json' -d ' { "settings" : { "index.numberofshards" : 2 }
You can then add a document to
my-index-000002.
curl -X POST 'http://localhost:9200/my-index-000002/_doc?pretty' -H 'Content-Type: application/json' -d ' { "@timestamp": "2099-11-16T13:12:00", "message": "GET /search HTTP/1.1 200 1070000", "user": { "id": "kimchy" }
You can search and perform other operations on multiple indices with a single request. The following request searches
my-index-000001and
my-index-000002.
curl -X GET 'http://localhost:9200/my-index-000001,my-index-000002/search?pretty=true' -H 'Content-Type: application/json' -d ' { "query" : { "matchall" : {} }
You can omit the index from the request path to search all indices.
curl -X GET 'http://localhost:9200/search?pretty=true' -H 'Content-Type: application/json' -d ' { "query" : { "matchall" : {} }
=== Distributed, highly available
Let's face it; things will fail...
Elasticsearch is a highly available and distributed search engine. Each index is broken down into shards, and each shard can have one or more replicas. By default, an index is created with 1 shard and 1 replica per shard (1/1). Many topologies can be used, including 1/10 (improve search performance) or 20/1 (improve indexing performance, with search executed in a MapReduce fashion across shards).
To play with the distributed nature of Elasticsearch, bring more nodes up and shut down nodes. The system will continue to serve requests (ensure you use the correct HTTP port) with the latest data indexed.
=== Where to go from here?
We have just covered a tiny portion of what Elasticsearch is all about. For more information, please refer to the https://www.elastic.co/products/elasticsearch[elastic.co] website. General questions can be asked on the https://discuss.elastic.co[Elastic Forum] or https://ela.st/slack[on Slack]. The Elasticsearch GitHub repository is reserved for bug reports and feature requests only.
=== Building from source
Elasticsearch uses https://gradle.org[Gradle] for its build system.
To build a distribution for your local OS and print its output location upon
./gradlew :distribution:archives:linux-tar:assemble ./gradlew :distribution:archives:darwin-tar:assemble
Finished distributions are output to
distributions/archives.
See the xref:TESTING.asciidoc[TESTING] for more information about running the Elasticsearch test suite.
=== Upgrading from older Elasticsearch versions
To ensure a smooth upgrade process from earlier versions of Elasticsearch, please see our https://www.elastic.co/guide/en/elasticsearch/reference/current/setup-upgrade.html[upgrade documentation] for more details on the upgrade process.