# Elastic Search

Distributed Search and Analysis Engine and NoSQL database

Based on Lucene.

Features:

1. RestFul API for searching and indexing
2. Free text searching
3. Built-in sharding, indexing, replication
4. Key-Value store and field filtering and searching
5. Machine learning searching
6. Elastic stack for big data analyzing


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://liuzhenglaichn.gitbook.io/system-design/todo-1/elastic-search.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.