[toc]
单文档 get API
1. Get基本查询
GET weibo/_doc/1output:
{
"_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查询文档是否存在
GET weibo/_doc/2 结果:
{
"_index" : "weibo",
"_type" : "_doc",
"_id" : "2",
"found" : false
}可以看到id=2的文档不存在:
HEAD weibo/_doc/2 结果: 404 - Not Found
文档id=1是存在的: GET weibo/_doc/1 结果:
{
"_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查询: HEAD weibo/_doc/1, 结果: 200 - OK
HEAD: 查不到: 404; 查得到: 200;
3. get查询索引的实时性
如果文档已经更新，但还没有刷新，那么get API将发出一个刷新调用，使文档可见; 默认情况下，get API就是实时的，不受索引刷新速率的影响.(当然也可以禁用realtime GET，可将realtime参数设为false。)
4. \ _source的禁用
默认情况下，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)
如果您只要source中的一个或两个字段，可以使用_source_include和_source_exclude参数来包含或过滤:
- _source_includes 只想查询 \_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 上述的包含, 可以简写为: _source
GET weibo/_doc/1?_source=user,message- source_excludes 想排除 \_source节点中的 message 字段, 其余的全展示:
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. 直接使用\_source获取数据
使用/{index}/\_source/{id} 只获取文档的\_source字段，而不包含任何其他附加内容。例如:
GET weibo/_source/1{
"user" : "niewj",
"post_date" : "2009-11-15T14:12:12",
"message" : "trying out Elasticsearch"
}可以看到, 只有纯数据返回; 也可以使用上面的 _source的过滤字段:
GET weibo/_source/1?_source=user{
"user" : "niewj"
}7. 索引时的stored_fields参数
默认情况下，字段值被索引以使其可搜索，但不存储它们(的原始值); 这意味着可以查到字段，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=1
PUT twitter/_doc/1
{
"counter" : 1,
"tags" : ["red"]
}查询 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"
]
}
}都可以查到; 使用 stored_fields 参数查询 : 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"
]
}
}可以看到, 没了 counter 字段; 因为mapping里设置了 store: false
8. 索引查询性能相关参数之: refresh
refresh设为true，以在get之前刷新相关分片，使其可搜索。在将其设置为true之前，应该仔细考虑并确认: 因为这可能导致系统负载过重(降低索引速度)。