Elasticsearch Hello World：全文搜索入门

目标

创建索引、插入文档、执行全文搜索和聚合分析，理解 ES 的 RESTful 搜索范式。

完整代码（curl）

# 1. 创建索引（含 mapping）
curl -X PUT "http://localhost:9200/library" -H "Content-Type: application/json" -d '{
  "mappings": {
    "properties": {
      "title": {"type": "text", "analyzer": "standard"},
      "author": {"type": "keyword"},
      "year": {"type": "integer"},
      "pages": {"type": "integer"},
      "tags": {"type": "keyword"},
      "description": {"type": "text"}
    }
  }
}'

# 2. 批量插入文档（_bulk API）
curl -X POST "http://localhost:9200/library/_bulk" -H "Content-Type: application/json" -d '
{"index": {"_id": "1"}}
{"title": "深入理解计算机系统", "author": "Randal E. Bryant", "year": 2015, "pages": 1080, "tags": ["cs", "systems"], "description": "从程序员视角理解计算机系统"}
{"index": {"_id": "2"}}
{"title": "算法导论", "author": "Thomas H. Cormen", "year": 2009, "pages": 1312, "tags": ["algorithms", "textbook"], "description": "全面介绍算法的经典教材"}
{"index": {"_id": "3"}}
{"title": "计算机网络：自顶向下方法", "author": "James F. Kurose", "year": 2017, "pages": 864, "tags": ["networking", "textbook"], "description": "计算机网络入门经典"}
{"index": {"_id": "4"}}
{"title": "操作系统概念", "author": "Abraham Silberschatz", "year": 2018, "pages": 976, "tags": ["os", "textbook"], "description": "操作系统原理经典教材"}
'

# 3. 全文搜索（match query）
curl -X GET "http://localhost:9200/library/_search" -H "Content-Type: application/json" -d '{
  "query": {
    "match": {
      "title": "计算机 系统"
    }
  }
}'

# 4. 多字段搜索
curl -X GET "http://localhost:9200/library/_search" -H "Content-Type: application/json" -d '{
  "query": {
    "multi_match": {
      "query": "algorithm textbook",
      "fields": ["title^2", "description"]
    }
  }
}'

# 5. 过滤器 + 搜索
curl -X GET "http://localhost:9200/library/_search" -H "Content-Type: application/json" -d '{
  "query": {
    "bool": {
      "must": {"match": {"description": "经典"}},
      "filter": {"range": {"year": {"gte": 2015}}}
    }
  }
}'

# 6. 聚合分析（按 tag 分组统计）
curl -X GET "http://localhost:9200/library/_search" -H "Content-Type: application/json" -d '{
  "size": 0,
  "aggs": {
    "by_tag": {
      "terms": {"field": "tags"}
    }
  }
}'

# 7. 高亮显示
curl -X GET "http://localhost:9200/library/_search" -H "Content-Type: application/json" -d '{
  "query": {"match": {"description": "经典"}},
  "highlight": {
    "fields": {"description": {}}
  }
}'

Python 版本

# pip install elasticsearch
from elasticsearch import Elasticsearch

es = Elasticsearch(['http://localhost:9200'])

# 创建索引
es.indices.create(index='library', body={
    'mappings': {
        'properties': {
            'title': {'type': 'text'},
            'author': {'type': 'keyword'},
            'year': {'type': 'integer'},
            'tags': {'type': 'keyword'}
        }
    }
}, ignore=400)  # ignore 400 索引已存在

# 插入文档
doc = {
    'title': '深入理解计算机系统',
    'author': 'Randal E. Bryant',
    'year': 2015,
    'tags': ['cs', 'systems']
}
es.index(index='library', id=1, body=doc)

# 搜索
result = es.search(index='library', body={
    'query': {'match': {'title': '计算机'}},
    'highlight': {'fields': {'title': {}}}
})

for hit in result['hits']['hits']:
    print(f"得分 {hit['_score']:.2f}: {hit['_source']['title']}")
    if 'highlight' in hit:
        print(f"  高亮: {hit['highlight']['title']}")

# 聚合
agg_result = es.search(index='library', body={
    'size': 0,
    'aggs': {'popular_tags': {'terms': {'field': 'tags'}}}
})
for bucket in agg_result['aggregations']['popular_tags']['buckets']:
    print(f"{bucket['key']}: {bucket['doc_count']} 本")

预期输出

// 全文搜索结果
{
  "hits": {
    "total": {"value": 2},
    "hits": [
      {"_source": {"title": "深入理解计算机系统"}, "_score": 1.2},
      {"_source": {"title": "计算机网络：自顶向下方法"}, "_score": 0.8}
    ]
  }
}

// 聚合结果
{
  "aggregations": {
    "by_tag": {
      "buckets": [
        {"key": "textbook", "doc_count": 3},
        {"key": "algorithms", "doc_count": 1}
      ]
    }
  }
}

关键点

• text 类型字段会被分词，适合全文搜索；keyword 类型用于精确匹配和聚合
• _bulk API 高效批量导入
• bool query 组合 must/should/must_not/filter
• aggregations 实现分组统计，类似 SQL 的 GROUP BY
• 搜索结果按 _score（相关度评分）降序排列