Elasticsearch Essentials: Quick Start, Index Management, Mapping, and Advanced Operations

This article provides a comprehensive introduction to Elasticsearch, covering basic concepts, quick‑start commands, index management, mapping definitions, field types, dynamic mapping, and various maintenance operations.

Quick Start

Check cluster health: http://localhost:9200/_cat/health?v . View nodes: http://localhost:9200/_cat/?v . List indices: http://localhost:9200/_cat/indices?v .

Create an index named customer with pretty output:

PUT /customer?pretty

Index a document:

curl -X PUT "localhost:9200/customer/_doc/1?pretty" -H 'Content-Type: application/json' -d'{"name": "John Doe"}'

Retrieve the document:

curl -X GET "localhost:9200/customer/_doc/1?pretty"

Search all documents:

GET /customer/_search?q=*&sort=name:asc&pretty

Or using JSON body:

GET /customer/_search { "query": { "match_all": {} }, "sort": [ {"name": "asc"} ] }

Index Management

Create an index twitter with 3 primary shards and 2 replicas:

PUT twitter { "settings": { "index": { "number_of_shards": 3, "number_of_replicas": 2 } } }

Define a mapping for the index:

PUT twitter { "mappings": { "_doc": { "properties": { "type": {"type": "keyword"}, "name": {"type": "text"}, "user_name": {"type": "keyword"}, "email": {"type": "keyword"}, "content": {"type": "text"}, "tweeted_at": {"type": "date"} } } } }

Alias definition, index templates, and other advanced settings are demonstrated with examples such as:

PUT _template/template_1 { "index_patterns": ["te*", "bar*"], "settings": {"number_of_shards": 1}, "mappings": {"type1": {"_source": {"enabled": false}, "properties": {"host_name": {"type": "keyword"}, "created_at": {"type": "date", "format": "EEE MMM dd HH:mm:ss Z YYYY"}}} }

Mapping Details

Mapping defines field names, types, and attributes. Core datatypes include text , keyword , numeric types, date , and boolean. Complex types such as object and nested are also covered.

Example of a multi‑field definition:

PUT my_index { "mappings": {"_doc": {"properties": {"city": {"type": "text", "fields": {"raw": {"type": "keyword"}}}}}} }

Dynamic mapping automatically creates fields based on incoming JSON. Date detection and numeric detection can be enabled or disabled with settings like "date_detection": false or "numeric_detection": true .

Maintenance Operations

Cache clearing: POST /twitter/_cache/clear . Refresh: POST /_refresh . Flush: POST twitter/_flush . Force merge: POST /kimchy/_forcemerge?max_num_segments=1 .

Index shrink, split, rollover, and monitoring APIs are illustrated with the corresponding POST and GET requests.

Overall, the article serves as a practical reference for developers and engineers working with Elasticsearch, providing ready‑to‑use commands and explanations for everyday tasks.