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Elasticsearch is a distributed, highly scalable, high real-time search and data analysis engine. It can easily enable large amounts of data to be searched, analyzed and explored. Taking full advantage of the horizontal scalability of Elasticsearch can make data more valuable in the production environment. The implementation principle of Elasticsearch is mainly divided into the following steps. First, the user submits the data to the Elasticsearch database, and then uses the word segmentation controller to segment the corresponding sentence, and stores its weight and word segmentation results into the data. When the user searches for data At that time, the results will be ranked and scored according to the weight, and then the returned results will be presented to the user.
Elasticsearch is developed with a data collection and log parsing engine called Logstash and an analysis and visualization platform called Kibana. These three products are designed as an integrated solution called "Elastic Stack" (formerly known as "ELK stack").
Elasticsearch can be used to search various documents. It provides scalable search, has near real-time search, and supports multi-tenancy. Elasticsearch is distributed, which means that the index can be divided into shards, and each shard can have 0 or more replicas. Each node hosts one or more shards and acts as a coordinator to delegate operations to the correct shard. Rebalancing and routing is done automatically. Related data is usually stored in the same index, which consists of one or more primary shards and zero or more replica shards. Once an index is created, the number of primary shards cannot be changed.
Elasticsearch uses Lucene and tries to provide all its features through JSON and Java API. It supports facetting and percolating, which is useful for notifications if new documents match registration queries. Another feature, called "Gateway", handles the long-term durability of the index; for example, in case of a server crash, the index can be restored from the gateway. Elasticsearch supports real-time GET requests and is suitable as a NoSQL data store, but lacks distributed transactions.