Elasticsearch: More explanation needed about "type" field when making custom analyzers

[developerlicw]

Describe the feature:
In this page: https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-custom-analyzer.html , all fields/parameters used for making custom analyzer are explained except for "type", I am quite confused with what to put into this "type" field.
From the demo, I can see "custom" is used, but don't know if I can put any other words I like into this field.
My apologize if it is explained in other places.

Elasticsearch version (bin/elasticsearch --version):

Plugins installed: []

JVM version (java -version):

OS version (uname -a if on a Unix-like system):

Description of the problem including expected versus actual behavior:

Steps to reproduce:

Please include a minimal but complete recreation of the problem, including
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[tlrx]

The type here refers to the type of the built-in analyzer. If you look at the other analyzers you'll see that the type field has the value of standard for the Standard Analyzer, pattern for the Pattern Analyzer etc. I agree that the documentation could be improved on this.

[elasticmachine]

Pinging @elastic/es-search-aggs

[developerlicw]

Hi tlrx,
A lot thanks for your explanation, it's very useful to my work.
Hope that doc could be improved recently :)
I think this issue should be kept open till doc improved, please feel free to close it if necessary.

[lonlylocly]

Hello,

If you don't mind I would like to work on this and will submit a pull request in the upcoming days.

@tlrx Please tell me if I got this right: type in case of an analyzer can be any of those listed here:
https://github.com/elastic/elasticsearch/blob/b04faa059b50bfd8c55a5704c5bca432439ec85d/server/src/main/java/org/elasticsearch/indices/analysis/AnalysisModule.java#L242
plus any of the additional analyzers coming from the installed plugins.

So, when customizing analyzers there are two options:

• if type is in the list of built-in analyzers (standard, keyword, etc) then the new analyzer will be the built-in + your settings changed
• if type is custom - you can define your own chain of character filters/tokenizer/token filter (basically DIY analyzer from the building pieces available).

If this is correct, I will work on how to integrate this information into the documentation page and will submit a pull request.

Thank you.