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一、Elasticsearch?Script History-分布式全文搜索-脚本引擎历史
在ES早期的版本中，使用MVEL脚本，但为解决安全隐患问题，于是Groovy脚本诞生。
随之出现的安全漏洞跟内存泄露问题，于是在ES5.0版本之际，painless脚本官宣，距今也有数年之久，painless脚本浮现在开发者眼前。
二、Elasticsearch?Script ApplyCenarios-分布式全文搜索-脚本引擎应用场景
我们都很熟悉的认知到Elasticsearch全文搜索引擎，在其各版本系列中提供了丰富的dsl语法-增删改查-这里以6.x版本系列-6.8.6为例。
在80%以上的业务场景中作增删改查游刃有余，但应用于相对复杂的业务场景：
多字段自定义更新、自定义reindex、自定义数组字段动态添加...
当然基于脚本引擎手动开发插件也是可以实现的。
从painless脚本的衍生意义理解是"无痛"无漏洞的，但尤其需要注意的地方-不能以root账户启动es，不要公开es路径至其他用户。
从官方Script使用的介绍来看，首要就是性能问题，其次就是使用业务场景，ebay在性能优化实践英文版中也有体现，这里也mark下中文版。
其中，80%以上的业务场景：参考小编汇总Elasticsearch+Kibana+Dsl-Crud大全
GET _search{"query": {"match_all": {}}}#节点信息GET _cat/nodes?v#各节点机器存储信息GET _cat/allocation?v#索引信息GET _cat/indices?v#分片信息GET _cat/shards?v#注册快照存储库-仓库共享PUT _snapshot/my_backup{"type": "fs","settings": {"location": "/home/user/yxd179/es/backup"}}#查看仓库信息GET /_snapshot/my_backup?pretty#查看快照存储库保存结果GET _snapshot#创建快照，这个会备份所有打开的索引到my_backup仓库下并命名为snapshot_phr的快照里。这个调用会立刻返回，然后快照会在后台运行。若是希望在脚本中一直等待到完成，可通过添加 wait_for_completion 标记实现，这个会阻塞调用直到快照完成（如果是大型快照，会花很长时间才返回），其中只会备份索引809iJpOmSI2ZmJrUqKRR0Q信息PUT /_snapshot/my_backup/snapshot_yd?wait_for_completion=true{"indices": "809iJpOmSI2ZmJrUqKRR0Q","ignore_unavailable": true,"include_global_state": false,"metadata": {"taken_by": "phr","taken_because": "backup before upgrading"}}#查看快照GET /_snapshot/my_backup/snapshot_yd#查看所有快照GET /_snapshot/my_backup/_all#删除快照DELETE /_snapshot/my_backup/snapshot_yd#监控快照创建或恢复过程GET /_snapshot/my_backup/snapshot_yd/_status#恢复快照POST /_snapshot/my_backup/snapshot_yd/_restore#动态模板PUT /_template/yxd179_tpl{"index_patterns": ["yxd179-2021*"],"settings": {"number_of_shards": 1,"number_of_replicas": 1},"mappings": {"yd": {"dynamic_templates": [{"strings": {"match_mapping_type": "string","mapping": {"type": "text","index": true,"copy_to": "full_context","analyzer": "ik_max_word","fields": {"keyword": {"type": "keyword","ignore_above": 256}}}}}],"properties": {"full_context": {"type": "text","analyzer": "ik_max_word","fielddata": true,"store": true}}}}}?#副本分片分配设置PUT /yxd179-2021/_settings{"number_of_replicas": "1"}?#分页查询GET /yxd179-2021/yd/_search{"from": 0,"size": 30}?#根据ID查询GET /yxd179-2021/yd/647461503271768064?#bool query dsl查询GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"bool": {"should": [{"match": {"regNumber": "20203030651"}}]}},{"term": {"status": "1"}}]}},"sort": [{"createTime": {"order": "desc"}}],"from": 0,"size": 10}?#允许ES最大滚动数目分配设置PUT /yxd179-2021/_settings{"index": {"max_result_window": 13000000}}?#查看字段分词分析过程POST /yxd179-2021/_analyze{"field": "regNumber","text": "国械标准20203030651号"}?#模糊查询匹配GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"bool": {"should": [{"wildcard": {"regNumber.keyword": "*20203030651*"}}]}},{"term": {"status": "1"}}]}},"sort": [{"createTime": {"order": "desc"}}],"from": 0,"size": 10}?#对指定字段设置分词器查询GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"match": {"hdsd0001004": {"query": "1828551417","analyzer": "char_analyzer"}}}]}},"from": 0,"size": 30}?#模糊查询匹配GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"wildcard": {"hdsd0001002.keyword": "*yxd179*"}}]}},"from": 0,"size": 30}?#关闭索引:POST yxd179-2021/_close?#打开索引:POST yxd179-2021/_open?#对指定字段设置分词器PUT /yxd179-2021/_mapping/yd{"properties": {"hdsd0001004": {"type": "text","analyzer": "char_analyzer"}}}?#查看mapping结构体信息GET yxd179-2021/_mapping?#设置分词分析器PUT yxd179-2021/_settings{"analysis": {"analyzer": {"char_analyzer": {"tokenizer": "char_tokenizer","filter": "lowercase"}},"tokenizer": {"char_tokenizer": {"type": "pattern","pattern": "|"}}}}?#minimum_should_matchGET /yxd179-2021/yd/_search{"query": {"query_string": {"query": "182855141y7","type": "phrase","operator": "AND","minimum_should_match": "100%","fields": ["hdsd0001004"]}}}?#显示字段GET /yxd179-2021/yd/_search{"_source": {"include": ["id","productId"]},"query": {"bool": {"must": [{"terms": {"productId": [636654265306419462]}}]}},"from": 0,"size": 30}?#高亮查询GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"bool": {"should": []}},{"term": {"status": "1"}},{"term":{"id":636662671736099971}}]}},"sort": [{"id": {"order": "asc"}}],"highlight": {"pre_tags": ["<span class='title-key'>"],"post_tags": ["</span>"],"fields": {"commonName": {"type": "plain"}}},"from": 0,"size": 10}?#read_only_allow_deletePUT /yxd179-2021/_settings{"index":{"blocks":{"read_only_allow_delete":"false"}}}?#查询模板GET /_template?GET /yxd179-2021*/yd/_search{"from": 0,"size": 30}?#单个字段bool查询GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"term": {"id": "636651493706133509"}}]}},"from": 0,"size": 30}?#批量POST /_bulk{"index":{"_index":"yxd179-2021","_type":"yd","_id":"65965969996688"}}{"id":"65965969996688","HDSD0001002":"sdff","HDSD0001008":"fsdf","HDSD0001006":"000000000000000000","create_time":"2021-07-29","cancel_flag":0}{"index":{"_index":"yxd179-2021","_type":"yd","_id":"66049829996688"}}{"id":"66049829996688","HDSD0001002":"sdgsdg","HDSD0001008":"fsdfsdf","HDSD0001006":"000000000000000000","create_time":"2021-07-29","cancel_flag":1}?#外层交集查询GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"bool": {"should": [{"match": {"regNumber": "国sd20182642128"}}]}},{"term": {"status": "1"}}]}},"sort": [{"createTime": {"order": "desc"}}],"from": 0,"size": 10}?#复杂bool带权重查询-得分排序GET /yxd179-2021/yd/_search{"from": 0,"size": 10,"query": {"bool": {"must": [{"bool": {"must": [{"term": {"cancelFlag": {"value": "0","boost": 1}}}],"adjust_pure_negative": true,"boost": 1}},{"bool": {"should": [{"match": {"yhe": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}},{"match": {"yhr": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}},{"match": {"yht": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}},{"match": {"yhg": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}}],"adjust_pure_negative": true,"boost": 1}}],"adjust_pure_negative": true,"boost": 1}},"explain": true,"sort": [{"id": {"order": "desc"}}]}??#查询耗时统计分析profileGET /yxd179-2021/yd/_search{"profile": true,"query":{"term":{"tu":6583120}}}?#根据ID修改POST /yxd179-2021/yd/b00e89b652484b0b8da16e090302e012/_update{"doc":{"fd":"1"}}?#修改_update_by_query脚本引擎painlessPOST /yxd179-2021/_update_by_query{"query":{"term":{"fdh":6583120}},"script":{"lang":"painless","source": "ctx._source.cancelFlag=params.cancelFlag;ctx._source.updateTime=params.updateTime","params": {"cancelFlag":"0","updateTime":"2021-07-28T01:17:36.000Z"}}}?#交集查询-且保留-全GET /yxd179-2021/yd/_search{"query": {"bool": {"must": [{"term": {"cancelFlag": "0"}},{"bool": {"must": [{"wildcard": {"hdsd0001002.keyword": "*yxd179*"}},{"match": {"hdsd0001003": "2"}}]}}]}},"sort": [{"id": {"order": "desc"}}],"highlight": {"pre_tags": ["<span class='title-key'>"],"post_tags": ["</span>"],"fields": {"hdsd0001002": {"type": "plain"}}},"from": 0,"size": 30}??#外层交集查询-里层交集查询GET /yxd179-2021/yd/_search{"from": 0,"size": 10,"query": {"bool": {"must": [{"bool": {"must": [{"term": {"cancelFlag": {"value": "0","boost": 1}}}],"adjust_pure_negative": true,"boost": 1}},{"bool": {"must": [{"match": {"hdsd0001002": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}},{"match": {"hdsd0001003": {"query": "2","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}}],"adjust_pure_negative": true,"boost": 1}}],"adjust_pure_negative": true,"boost": 1}},"explain": true}??#并集查询GET /yxd179-2021/yd/_search{"from": 0,"size": 10,"query": {"bool": {"must": [{"term": {"cancelFlag": {"value": "0","boost": 1}}}],"should": [{"match": {"hdsd0001002": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}}],"adjust_pure_negative": true,"boost": 1}},"explain": true}?#并集查询-字段显示GET /yxd179-2021/yd/_search{"from": 0,"size": 10,"query": {"bool": {"must": [{"match": {"cancelFlag": {"query": "0","operator": "AND","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}}],"should": [{"match": {"hdsd0001002": {"query": "张","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}},{"match": {"hdsd0001002.pinyin": {"query": "zhang","operator": "OR","prefix_length": 0,"max_expansions": 50,"fuzzy_transpositions": true,"lenient": false,"zero_terms_query": "NONE","auto_generate_synonyms_phrase_query": true,"boost": 1}}}],"adjust_pure_negative": true,"boost": 1}},"explain": true,"_source": {"includes": ["id","th001Id","createTime","updateTime","hdsd0001001","hdsd0001002","cancelFlag"],"excludes": []}}??#若需要更频繁的更新，可以使用es api强制更新GET /yxd179-2021/_refresh?#根据ID删除DELETE /yxd179-2021/yd/ud6-5XkBwVbB7HKjg5k0?#删除索引DELETE /yxd179-2021?#删除模板-动态mappingDELETE /_template/yxd179_tpl?#排序GET /yxd179-2021/yd/_search{"sort": [{"createTime": {"order": "desc"}}],"from": 0,"size": 30}
三、Elasticsearch?Script ActualCombat-分布式全文搜索-脚本引擎实战
这里仅以Update-By-Query为例：
?其中，lang指定脚本引擎：painless，source中为script脚本片段，params为脚本参数值。
之所以通过params传递，可突破ES对脚本编译限制，虽然也可以通过下面操作来修改该解析上限的配置：
PUT /_cluster/settings
{
"transient": {
"script.max_compilations_per_minute": 40
}
}重要：对于大批量数据，ES都需要单独的编译解析，当进行bulk update时，若是每一个脚本都实时编译的话，可想而知很快就会达到上限。知其然知其所以然，对于ES中都只会在第一次进行解析这个脚本，之后便无需再次解析，当脚本中有常数变量时，ES会实时编译脚本，故结合script中的param功能，设法将脚本中的变量通过param传递进去，从而可以从根本上解决脚本编译解析限制的问题。
接下来，我们看下在Java中怎么样基于6.8.6版本构建tcp client执行painless脚本引擎？
补充：对updateByQuery?API的调用从获取索引快照开始，索引使用内部版本控制找到任何文档。
试想当一个文档在快照的时间和索引请求过程之间发生变化时，会发生版本冲突。当版本匹配时，updateByQuery更新文档并增加版本号。上述为了防止版本冲突导致updateByQuery中止，还可以设abortOnVersionConflict(false)，之所以这么做，是有可能它试图获取在线映射更改，而版本冲突意味着在相同时间开始updateByQuery和试图更新文档的冲突文档，该更新将获取在线映射更新，updateByQuery也可以通过指定pipeline来使用ingest节点。其中UpdateByQueryRequestBuilder?API可支持过滤更新的文档，限制要更新的文档总数，并使用脚本更新文档，即时刷入磁盘，重试次数等。
Retry：
当客户端A、B几乎同时获取同一个文档, 一并获得_version版本信息, 假设此时_version=1。
接着，客户端A修改文档中的部分内容, 将修改写入索引。而Elasticsearch在写入索引时, 检查客户端A提交的文档的版本信息(这里仍然是1) 和 现存的文档的版本信息(这里也是1), 发现相同后, 执行写入操作, 并修改版本号_version=2。然后客户端B也修改文档中的部分内容, 其操作写回索引的速度稍慢，此时同样执行写入过程，ES发现客户端B提交的文档的版本为1, 而现存文档的版本为2，即发生冲突，此次partial update将失败-重试。
并发控制策略：partial update并发控制策略-乐观锁
小试牛刀案例：如何通过脚本引擎指定多个字段update？
方式No.1：
ctx._source.putAll(params) 方式No.2：
for (k in params.keySet()){if (!k.equals('ctx')){ctx._source.put(k, params.get(k))}}