Table of contents
1. Overview of Elasticsearch
2. Introduction to elasticsearch
1. Overview of Elasticsearch
(1) What is elasticsearch?
The Elastic Stack,
including
Elasticsearch
,
Kibana
,
Beats
, and
Logstash
(also known as
the ELK Stack
).
Elaticsearch, referred to as ES
,
ES
is an
open source, highly scalable distributed full-text search engine and
is the core of the entire Elastic search engine.
The core of the Stack technology stack. It can store and retrieve the results we want from massive data in near real-time.
(2) Full-text search engine
In general, full-text retrieval in traditional databases is poorly implemented because generally no one uses data inventory text fields. Enter
Full-text search requires scanning the entire table . If the amount of data is large, even optimizing the SQL syntax will have little effect. establish
The index is set up, but it is very troublesome to maintain.
The index will be rebuilt for insert
and update operations.
Full-text search engines refer to mainstream search engines that are currently widely used. It works like a computer
The indexing program scans each word in the article and creates an index for each word , indicating where the word appears in the article.
times and positions. When the user queries, the retrieval program searches based on the pre-established index and returns the search results.
Feed to the user's retrieval method. This process is similar to the process of looking up a word through the search word list in a dictionary.
As a full-text search engine, Elasticsearch has the following
advantages
:
1. Distributed architecture : Elasticsearch has the ability to scale horizontally and can disperse data across multiple nodes to achieve high availability and high concurrency .
2. Efficient indexing and search: Elasticsearch is based on advanced inverted index technology, which can quickly perform text retrieval and aggregation operations, while supporting complex query statements.
3. Text processing function : Elasticsearch has a variety of built-in text processors, including word breakers, filters, etc., which can process, normalize and optimize text to improve the quality and accuracy of search .
4. Real-time search and update: Elasticsearch can perform real-time search and dynamic update within milliseconds, supports batch operations and asynchronous processing, ensuring the efficiency and flexibility of the system.
2. Introduction to elasticsearch
(1) Elasticsearch software download
The official address of Elasticsearch:
https://www.elastic.co/cn/
.
The latest version of Elasticsearch is
7.11.2
(as of
2021.3.10
). We choose version
7.8.0
(the latest version half a year ago) download address:
https://www.elastic.co/cn/downloads/past-releases#elasticsearch
(2) Install elasticsearch
(3) Start elasticsearch
(4) Problem solving
Elasticsearch is
developed using
Java , and
ES version 7.8 requires JDK version 1.8 or above, which is installed by default.
The package comes with
a jdk
environment. If the system is configured with
JAVA_HOME
, then the system default
JDK is used
. If it is not configured
The configuration uses the built-in
JDK
. It is generally recommended to use the system-configured
JDK
. Double-click the startup window to crash, and track the error through path access. If it is "insufficient space", please modify the config/jvm.options configuration file. Modify parameters as follows
