Token filters (lowercase, stemmer, synonym) in Elasticsearch - Cheat Sheet & Quick Revision

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beginner

What does the lowercase token filter do in Elasticsearch?

The lowercase token filter converts all characters in tokens to lowercase. This helps make searches case-insensitive, so 'Apple' and 'apple' are treated the same.

beginner

Explain the purpose of a stemmer token filter.

A stemmer token filter reduces words to their root form. For example, 'running', 'runs', and 'ran' become 'run'. This helps match different forms of a word during search.

beginner

What is a synonym token filter used for?

A synonym token filter replaces words with their synonyms during indexing or searching. For example, 'quick' might be replaced with 'fast'. This expands search results to include similar meanings.

intermediate

How do token filters fit into the Elasticsearch analysis process?

Token filters process tokens after the text is split by the tokenizer. They modify tokens by changing case, stemming, or adding synonyms before indexing or searching.

intermediate

Give an example of how to define a lowercase and stemmer token filter in Elasticsearch settings.

Example settings snippet:

{
  "analysis": {
    "filter": {
      "my_lowercase": { "type": "lowercase" },
      "my_stemmer": { "type": "stemmer", "language": "english" }
    }
  }
}

What does the lowercase token filter do in Elasticsearch?

A Converts all tokens to lowercase

B Removes stop words

C Splits text into tokens

D Adds synonyms to tokens

The lowercase token filter converts all tokens to lowercase to make searches case-insensitive.

Which token filter reduces words to their root form?

A Stop filter

B Synonym filter

C Lowercase filter

D Stemmer filter

The stemmer filter reduces words to their root form, like 'running' to 'run'.

What is the main use of a synonym token filter?

A To convert tokens to lowercase

B To remove punctuation

C To replace words with their synonyms

D To split text into tokens

The synonym filter replaces words with their synonyms to expand search results.

In which part of the analysis process do token filters operate?

A After tokenizing text

B Before tokenizing text

C During indexing only

D Only during searching

Token filters modify tokens after the tokenizer splits the text.

Which of these is a correct way to define a lowercase filter in Elasticsearch settings?

A "filter": { "my_lowercase": { "type": "synonym" } }

B "filter": { "my_lowercase": { "type": "lowercase" } }

C "filter": { "my_lowercase": { "type": "stemmer" } }

D "filter": { "my_lowercase": { "type": "tokenizer" } }

The lowercase filter is defined with type "lowercase" in the filter settings.

Describe how lowercase, stemmer, and synonym token filters help improve search results in Elasticsearch.

Think about how each filter changes the words to match more queries.

Explain the order of operations in Elasticsearch analysis involving tokenizers and token filters.

Remember token filters work after tokenizing.