ELK-Elasticsearch 基础使用

一、基本概念

1 Node 与 Cluster

Elastic 本质上是一个分布式数据库，允许多台服务器协同工作，每台服务器可以运行多个 Elastic 实例。单个 Elastic 实例称为一个节点（node）。一组节点构成一个集群（cluster）。

2 Index

Elastic 会索引所有字段，经过处理后写入一个反向索引（Inverted Index）。查找数据的时候，直接查找该索引。

所以，Elastic 数据管理的顶层单位就叫做 Index（索引）。它是单个数据库的同义词。每个 Index （即数据库）的名字必须是小写

3 Document

Index 里面单条的记录称为 Document（文档）。许多条 Document 构成了一个 Index。

Document 使用 JSON 格式表示。同一个 Index 里面的 Document，不要求有相同的结构（scheme），但是最好保持相同，这样有利于提高搜索效率。

4 Type

Document 可以分组，比如weather这个 Index 里面，可以按城市分组（北京和上海），也可以按气候分组（晴天和雨天）。这种分组就叫做 Type，它是虚拟的逻辑分组，用来过滤 Document。

不同的 Type 应该有相似的结构（schema），举例来说，id字段不能在这个组是字符串，在另一个组是数值。这是与关系型数据库的表的一个区别。性质完全不同的数据（比如products和logs）应该存成两个 Index，而不是一个 Index 里面的两个 Type（虽然可以做到）。

根据规划，Elastic 6.x 版只允许每个 Index 包含一个 Type，7.x 版将会彻底移除 Type。

二、操作

1：查看ES版本信息

[elk@es logs]$ curl -GET 'http://localhost:9250'
{
  "name" : "elk01",
  "cluster_name" : "elk-cluster",
  "cluster_uuid" : "KW6Nr_pTSVuwT0gR0agtOA",
  "version" : {
    "number" : "5.3.1",
    "build_hash" : "5f9cf58",
    "build_date" : "2017-04-17T15:52:53.846Z",
    "build_snapshot" : false,
    "lucene_version" : "6.4.2"
  },
  "tagline" : "You Know, for Search"
}
[elk@es logs]$ 

ES返回一个json文本信息，包括版本、当前节点、集群等等信息

默认情况下，Elastic 只允许本机访问，如果需要远程访问，可以修改 Elastic 安装目录的config/elasticsearch.yml文件，去掉network.host的注释，将它的值改

0.0.0.0，然后重新启动 Elastic。

上面代码中，设成0.0.0.0让任何人都可以访问。线上服务不要这样设置，要设成具体的 IP。

2：查看索引列表

[elk@es logs]$ curl -X GET 'http://localhost:9250/_cat/indices?v'
health status index     uuid                   pri rep docs.count docs.deleted store.size pri.store.size
yellow open   textindex r8Mj0h23TBO6uP6tBLGylQ                                   650b           650b
[elk@es logs]$ 

此处返回我刚创建的一个索引(创建步骤下面叙述),具体各个含义值，可以使用help查看

[elk@es logs]$ curl -X GET 'http://localhost:9250/_cat/indices?help'
health                           | h                              | current health status
status                           | s                              | open/close status
index                            | i,idx                          | index name
uuid                             | id,uuid                        | index uuid
pri                              | p,shards.primary,shardsPrimary | number of primary shards
rep                              | r,shards.replica,shardsReplica | number of replica shards
docs.count                       | dc,docsCount                   | available docs
docs.deleted                     | dd,docsDeleted                 | deleted docs
creation.date                    | cd                             | index creation date (millisecond value)
creation.date.string             | cds                            | index creation date (as string)
store.size                       | ss,storeSize                   | store size of primaries & replicas
pri.store.size                   |                                | store size of primaries
completion.size                  | cs,completionSize              | size of completion
pri.completion.size              |                                | size of completion
fielddata.memory_size            | fm,fielddataMemory             | used fielddata cache
pri.fielddata.memory_size        |                                | used fielddata cache
fielddata.evictions              | fe,fielddataEvictions          | fielddata evictions
pri.fielddata.evictions          |                                | fielddata evictions
query_cache.memory_size          | qcm,queryCacheMemory           | used query cache
pri.query_cache.memory_size      |                                | used query cache
query_cache.evictions            | qce,queryCacheEvictions        | query cache evictions
pri.query_cache.evictions        |                                | query cache evictions
request_cache.memory_size        | rcm,requestCacheMemory         | used request cache
pri.request_cache.memory_size    |                                | used request cache
request_cache.evictions          | rce,requestCacheEvictions      | request cache evictions
pri.request_cache.evictions      |                                | request cache evictions
request_cache.hit_count          | rchc,requestCacheHitCount      | request cache hit count
pri.request_cache.hit_count      |                                | request cache hit count
request_cache.miss_count         | rcmc,requestCacheMissCount     | request cache miss count
pri.request_cache.miss_count     |                                | request cache miss count
flush.total                      | ft,flushTotal                  | number of flushes
pri.flush.total                  |                                | number of flushes
flush.total_time                 | ftt,flushTotalTime             | time spent in flush
pri.flush.total_time             |                                | time spent in flush
get.current                      | gc,getCurrent                  | number of current get ops
pri.get.current                  |                                | number of current get ops
get.time                         | gti,getTime                    | time spent in get
pri.get.time                     |                                | time spent in get
get.total                        | gto,getTotal                   | number of get ops
pri.get.total                    |                                | number of get ops
get.exists_time                  | geti,getExistsTime             | time spent in successful gets
pri.get.exists_time              |                                | time spent in successful gets
get.exists_total                 | geto,getExistsTotal            | number of successful gets
pri.get.exists_total             |                                | number of successful gets
get.missing_time                 | gmti,getMissingTime            | time spent in failed gets
pri.get.missing_time             |                                | time spent in failed gets
get.missing_total                | gmto,getMissingTotal           | number of failed gets
pri.get.missing_total            |                                | number of failed gets
indexing.delete_current          | idc,indexingDeleteCurrent      | number of current deletions
pri.indexing.delete_current      |                                | number of current deletions
indexing.delete_time             | idti,indexingDeleteTime        | time spent in deletions
pri.indexing.delete_time         |                                | time spent in deletions
indexing.delete_total            | idto,indexingDeleteTotal       | number of delete ops
pri.indexing.delete_total        |                                | number of delete ops
indexing.index_current           | iic,indexingIndexCurrent       | number of current indexing ops
pri.indexing.index_current       |                                | number of current indexing ops
indexing.index_time              | iiti,indexingIndexTime         | time spent in indexing
pri.indexing.index_time          |                                | time spent in indexing
indexing.index_total             | iito,indexingIndexTotal        | number of indexing ops
pri.indexing.index_total         |                                | number of indexing ops
indexing.index_failed            | iif,indexingIndexFailed        | number of failed indexing ops
pri.indexing.index_failed        |                                | number of failed indexing ops
merges.current                   | mc,mergesCurrent               | number of current merges
pri.merges.current               |                                | number of current merges
merges.current_docs              | mcd,mergesCurrentDocs          | number of current merging docs
pri.merges.current_docs          |                                | number of current merging docs
merges.current_size              | mcs,mergesCurrentSize          | size of current merges
pri.merges.current_size          |                                | size of current merges
merges.total                     | mt,mergesTotal                 | number of completed merge ops
pri.merges.total                 |                                | number of completed merge ops
merges.total_docs                | mtd,mergesTotalDocs            | docs merged
pri.merges.total_docs            |                                | docs merged
merges.total_size                | mts,mergesTotalSize            | size merged
pri.merges.total_size            |                                | size merged
merges.total_time                | mtt,mergesTotalTime            | time spent in merges
pri.merges.total_time            |                                | time spent in merges
refresh.total                    | rto,refreshTotal               | total refreshes
pri.refresh.total                |                                | total refreshes
refresh.time                     | rti,refreshTime                | time spent in refreshes
pri.refresh.time                 |                                | time spent in refreshes
refresh.listeners                | rli,refreshListeners           | number of pending refresh listeners
pri.refresh.listeners            |                                | number of pending refresh listeners
search.fetch_current             | sfc,searchFetchCurrent         | current fetch phase ops
pri.search.fetch_current         |                                | current fetch phase ops
search.fetch_time                | sfti,searchFetchTime           | time spent in fetch phase
pri.search.fetch_time            |                                | time spent in fetch phase
search.fetch_total               | sfto,searchFetchTotal          | total fetch ops
pri.search.fetch_total           |                                | total fetch ops
search.open_contexts             | so,searchOpenContexts          | open search contexts
pri.search.open_contexts         |                                | open search contexts
search.query_current             | sqc,searchQueryCurrent         | current query phase ops
pri.search.query_current         |                                | current query phase ops
search.query_time                | sqti,searchQueryTime           | time spent in query phase
pri.search.query_time            |                                | time spent in query phase
search.query_total               | sqto,searchQueryTotal          | total query phase ops
pri.search.query_total           |                                | total query phase ops
search.scroll_current            | scc,searchScrollCurrent        | open scroll contexts
pri.search.scroll_current        |                                | open scroll contexts
search.scroll_time               | scti,searchScrollTime          | time scroll contexts held open
pri.search.scroll_time           |                                | time scroll contexts held open
search.scroll_total              | scto,searchScrollTotal         | completed scroll contexts
pri.search.scroll_total          |                                | completed scroll contexts
segments.count                   | sc,segmentsCount               | number of segments
pri.segments.count               |                                | number of segments
segments.memory                  | sm,segmentsMemory              | memory used by segments
pri.segments.memory              |                                | memory used by segments
segments.index_writer_memory     | siwm,segmentsIndexWriterMemory | memory used by index writer
pri.segments.index_writer_memory |                                | memory used by index writer
segments.version_map_memory      | svmm,segmentsVersionMapMemory  | memory used by version map
pri.segments.version_map_memory  |                                | memory used by version map
segments.fixed_bitset_memory     | sfbm,fixedBitsetMemory         | memory used by fixed bit sets for nested object field types and type filters for types referred in _parent fields
pri.segments.fixed_bitset_memory |                                | memory used by fixed bit sets for nested object field types and type filters for types referred in _parent fields
warmer.current                   | wc,warmerCurrent               | current warmer ops
pri.warmer.current               |                                | current warmer ops
warmer.total                     | wto,warmerTotal                | total warmer ops
pri.warmer.total                 |                                | total warmer ops
warmer.total_time                | wtt,warmerTotalTime            | time spent in warmers
pri.warmer.total_time            |                                | time spent in warmers
suggest.current                  | suc,suggestCurrent             | number of current suggest ops
pri.suggest.current              |                                | number of current suggest ops
suggest.time                     | suti,suggestTime               | time spend in suggest
pri.suggest.time                 |                                | time spend in suggest
suggest.total                    | suto,suggestTotal              | number of suggest ops
pri.suggest.total                |                                | number of suggest ops
memory.total                     | tm,memoryTotal                 | total used memory
pri.memory.total                 |                                | total user memory
[elk@es logs]$ 

3：创建索引

[elk@es logs]$ curl -X PUT 'localhost:9250/abctest'
{"acknowledged":true,"shards_acknowledged":true}
[elk@es logs]$ 

创建索引名称，必须是小写，并且索引名称一旦创建，则不可以修改，acknowledged表示执行结果，true或false

4：删除索引

删除索引，只需要将PUT替换为DELETE即可

[elk@es logs]$ curl -X DELETE 'localhost:9250/abctest'
{"acknowledged":true}
[elk@es logs]$