[toc]

单文档 get API

1. Get根本查问

GET weibo/_doc/1

output:

{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "1",  "_version" : 3,  "_seq_no" : 2,  "_primary_term" : 1,  "found" : true,  "_source" : {    "user" : "niewj",    "post_date" : "2009-11-15T14:12:12",    "message" : "trying out Elasticsearch"  }}

2. head查问文档是否存在

GET weibo/_doc/2 后果:

{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "2",  "found" : false}

能够看到id=2的文档不存在:

HEAD weibo/_doc/2 后果: 404 - Not Found

文档id=1是存在的: GET weibo/_doc/1 后果:

{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "1",  "_version" : 3,  "_seq_no" : 2,  "_primary_term" : 1,  "found" : true,  "_source" : {    "user" : "niewj",    "post_date" : "2009-11-15T14:12:12",    "message" : "trying out Elasticsearch"  }}

用 HEAD查问: HEAD weibo/_doc/1, 后果: 200 - OK

HEAD: 查不到: 404; 查失去: 200;

3. get查问索引的实时性

如果文档曾经更新，但还没有刷新，那么get API将收回一个刷新调用，使文档可见; 默认状况下，get API就是实时的，不受索引刷新速率的影响.(当然也能够禁用realtime GET，可将realtime参数设为false。)

4. \ _source的禁用

默认状况下，get操作返回source内容，除非禁用_source字段:

GET weibo/_doc/1:

{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "1",  "_version" : 3,  "_seq_no" : 2,  "_primary_term" : 1,  "found" : true,  "_source" : {    "user" : "niewj",    "post_date" : "2009-11-15T14:12:12",    "message" : "trying out Elasticsearch"  }}

禁用: GET weibo/_doc/1?_source=false:

{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "1",  "_version" : 3,  "_seq_no" : 2,  "_primary_term" : 1,  "found" : true}

5. \_source字段的过滤(excludes/includes)

如果您只有source中的一个或两个字段，能够应用_source_include和_source_exclude参数来蕴含或过滤:

  • _source_includes 只想查问 \_source节点中的 user 和 message 字段:
GET weibo/_doc/1?_source_includes=user,message
{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "1",  "_version" : 3,  "_seq_no" : 2,  "_primary_term" : 1,  "found" : true,  "_source" : {    "message" : "trying out Elasticsearch",    "user" : "niewj"  }}
  • _source 上述的蕴含, 能够简写为: _source
GET weibo/_doc/1?_source=user,message
  • source_excludes 想排除 \_source节点中的 message 字段, 其余的全展现:
GET weibo/_doc/1?_source_excludes=message
{  "_index" : "weibo",  "_type" : "_doc",  "_id" : "1",  "_version" : 3,  "_seq_no" : 2,  "_primary_term" : 1,  "found" : true,  "_source" : {    "post_date" : "2009-11-15T14:12:12",    "user" : "niewj"  }}

6. 间接应用\_source获取数据

应用/{index}/\_source/{id} 只获取文档的\_source字段，而不蕴含任何其余附加内容。例如:

GET weibo/_source/1
{  "user" : "niewj",  "post_date" : "2009-11-15T14:12:12",  "message" : "trying out Elasticsearch"}

能够看到, 只有纯数据返回; 也能够应用下面的 _source的过滤字段:

GET weibo/_source/1?_source=user
{  "user" : "niewj"}

7. 索引时的stored_fields参数

默认状况下，字段值被索引以使其可搜寻，但不存储它们(的原始值); 这意味着能够查到字段，但不能检索其原始字段值。举例:

# 设置mapping中counter字段只索引不存储;tags字段索引且存储;PUT twitter{   "mappings": {       "properties": {          "counter": {             "type": "integer",             "store": false          },          "tags": {             "type": "keyword",             "store": true          }       }   }}

索引一条记录:

# 索引一条文档, id=1PUT twitter/_doc/1{    "counter" : 1,    "tags" : ["red"]}

查问 GET twitter/_doc/1

{  "_index" : "twitter",  "_type" : "_doc",  "_id" : "1",  "_version" : 1,  "_seq_no" : 0,  "_primary_term" : 1,  "found" : true,  "_source" : {    "counter" : 1,    "tags" : [      "red"    ]  }}

都能够查到; 应用 stored_fields 参数查问 : GET twitter/_doc/1?stored_fields=tags,counter:

{  "_index" : "twitter",  "_type" : "_doc",  "_id" : "1",  "_version" : 1,  "_seq_no" : 0,  "_primary_term" : 1,  "found" : true,  "fields" : {    "tags" : [      "red"    ]  }}

能够看到, 没了 counter 字段; 因为mapping里设置了 store: false

8. 索引查问性能相干参数之: refresh

refresh设为true，以在get之前刷新相干分片，使其可搜寻。在将其设置为true之前，应该认真思考并确认: 因为这可能导致系统负载过重(升高索引速度)。