Elasticsearch 创建索引如同 MySQL 创建数据库，es 提供了 RESTFul API 来创建索引，可以通过 PUT 命令快速创建一个默认配置的索引。
快速创建索引
快速创建一个 article 的索引，可以如下命令：
PUT http://127.0.0.1:9200/article
如上索引会采用默认的配置，Elasticsearch 默认给一个索引设置 5 个分片和 1 个副本，一个索引的分片数一旦指定后就不能再修改，而副本数可以通过命令随时修改。
值得注意的是，索引不能出现大写字母。
如果索引名称包含大写字母，会报如下错误信息：
{
"error": {
"root_cause": [{
"type": "invalid_index_name_exception",
"reason": "Invalid index name [Article], must be lowercase",
"index_uuid": "_na_",
"index": "Article"
}],
"type": "invalid_index_name_exception",
"reason": "Invalid index name [Article], must be lowercase",
"index_uuid": "_na_",
"index": "Article"
},
"status": 400
}
我们通过 CURL 命令演示一个 article 索引，看一下效果：
curl -X PUT "127.0.0.1:9200/article?pretty"
创建索引成功，返回如下信息：
{
"acknowledged" : true,
"shards_acknowledged" : true,
"index" : "article"
}
设置索引分片及副本
ES 的索引分片和副本可以通过 settings 参数在索引初始化时设置。假设给索引 article 分配 3 个分片和 0 个副本，命令如下：
PUT article
{
"settings": {
"number_of_shards": 3,
"number_of_replicas": 0
}
}
改变索引副本数
如上所述，索引创建后，分片数是不能再改变的，但是副本数允许可变。
比如，把 article 索引的副本数修改为 2 个，命令如下：
PUT article/_settings
{
"number_of_replicas": 2
}
创建带有静态映射类型的索引
其实，在生产环境中创建索引时，除了设置分片副本数外，还会同时将索引中字段类型映射通过 mappings 参数进行设置，如下示例：
PUT article
{
"settings": {
"number_of_shards": 3,
"number_of_replicas": 1
},
"mappings": {
"crawl_article": {
"_all": {
"enabled": false
},
"properties": {
"summary": {
"search_analyzer": "ik_smart",
"similarity": "BM25",
"analyzer": "ik_max_word",
"type": "text"
},
"title": {
"search_analyzer": "ik_smart",
"similarity": "BM25",
"analyzer": "ik_max_word",
"type": "text"
},
"content": {
"search_analyzer": "ik_smart",
"similarity": "BM25",
"analyzer": "ik_max_word",
"type": "text"
}
}
}
}
}
创建带有分析器的索引
Elasticsearch 创建索引时，也可以自定义的分析器（analyzer），下面给出带有自定义分析器、指定分片副本数及 mapping 映射的完整索引示例：
PUT article
{
"settings": {
"number_of_shards": 1,
"number_of_replicas": 0,
"analysis": {
"char_filter": {
"point_2_whitespace": {
"type": "mapping",
"mappings": [
".=>' '"
]
}
},
"analyzer": {
"my_ik_max_word": {
"char_filter": [
"html_strip",
"point_2_whitespace"
],
"tokenizer": "ik_max_word",
"filter": [
"lowercase"
]
},
"my_ik_smart": {
"char_filter": [
"html_strip",
"point_2_whitespace"
],
"tokenizer": "ik_smart",
"filter": [
"lowercase"
]
}
}
}
},
"mappings": {
"article": {
"_all": {
"enabled": false
},
"properties": {
"title": {
"search_analyzer": "my_ik_smart",
"similarity": "BM25",
"analyzer": "my_ik_max_word",
"type": "text"
},
"summary": {
"search_analyzer": "my_ik_smart",
"similarity": "BM25",
"analyzer": "my_ik_max_word",
"type": "text"
},
"content": {
"search_analyzer": "my_ik_smart",
"similarity": "BM25",
"analyzer": "my_ik_max_word",
"type": "text"
}
}
}
}
}