不爲也 比不能也

The Ranking Evaluation API that's been added to Elasticsearch is a new, experimental REST API that lets you quickly evaluate the quality of search results for a typical query set. This can be useful either while developing new search queries, incremental improvements of the query templates of an an existing system, or as a basic monitoring tool to detect changes in the search quality of a system..

Anybody who uses Elasticsearch for indexing time-based data such as log events is accustomed to the index-per-day pattern: use an index name derived from the timestamp of the logging event rounded to the nearest day, and new indices pop into existence as soon as they are required. The definition of the new index can be controlled ahead of time using index templates.log event처럼 시간 기반의 data를 index..

A rollover request in Elasticsearch 6.2.0 or later will be aborted if the same alias is found in the matching index templates. This change is to prevent the alias from pointing to multiple indices during rollover. If your index templates already contain the same alias, you should remove it by updating the index templates.Elasticsearch 6.2.0 이후부터, 일치하는 index template에서 동일한 alias가 발견되면, rollover r..

Strict REST query string parameter parsingeditPrevious versions of Elasticsearch ignored unrecognized URL query string parameters. This means that extraneous parameters or parameters containing typographical errors would be silently accepted by Elasticsearch. This is dangerous from an end-user perspective because it means a submitted request will silently execute not as intended. This leniency h..

Switched Default Language from Groovy to PainlesseditThe default scripting language for Elasticsearch is now Painless. Painless is a custom-built language with syntax similar to Groovy designed to be fast as well as secure. Many Groovy scripts will be identitical to Painless scripts to help make the transition between languages as simple as possible.Elasticsearch의 기본 script 언어는 이제 Painless이다. Pa..

Prior to 2.4, validation was not performed upon creation of an index template. Rather, the index template was validated upon index creation after all matching templates were fully merged.2.4 이전에서는, index template 생성시에 유효성 검증가 수행되지 않았다. 오히려, index template은 모든 일치하는 template이 완전히 병합된 후 index 생성시에 유효성이 검증되었다.Each index template must now be independently valid prior to merging. This means, for examp..

Until now, we have created a new index by simply indexing a document into it. The index is created with the default settings, and new fields are added to the type mapping by using dynamic mapping. Now we need more control over the process: we want to ensure that the index has been created with the appropriate number of primary shards, and that analyzers and mappings are set up beforewe index any..

If you know that you are going to be adding new fields on the fly, you probably want to leave dynamic mapping enabled. At times, though, the dynamic mapping "rules" can be a bit blunt. Fortunately, there are settings that you can use to customize these rules to better suit your data.새로운 field를 추가하려는 것을, 지금 알고 있다면, dynamic mapping을 비활성화하고 싶을 것이다. 때때로, 동적 mapping "규칙" 은 조금 무딜 수 있다. 다행히도, 데이터에 더 적합..

Often, all types in an index share similar fields and settings. It can be more convenient to specify these common settings in the _default_ mapping, instead of having to repeat yourself every time you create a new type. The _default_ mapping acts as a template for new types. All types createdafter the _default_ mapping will include all of these default settings, unless explicitly overridden in t..

Queries can find only terms that actually exist in the inverted index, so it is important to ensure that the same analysis process is applied both to the document at index time, and to the query string at search time so that the terms in the query match the terms in the inverted index.query는 inverted index에 실제로 존재하는 단어만을 찾을 수 있다. 따라서 document를 index할할 때 적용되는 프로세스와, 검색 시 query string에 적용되는 프로세스가,..