How deeply does Elasticsearch in Action, Second Edition cover edge n-gram indexing?

Defines prefix generation and shows tokenizer configuration and _analyze testing, while deferring detailed treatment to a later discussion.

Edge n-gram indexing

As explained in Elasticsearch in Action, Second Edition

An edge n-gram is an n-gram anchored at the beginning of a token.

Edge n-gram indexing breaks each token into prefixes anchored at its beginning. For “action,” it produces “a,” “ac,” “act,” “acti,” “actio,” and “action,” making partial input useful for typeahead-style search. section 4.6.6 section 7.7.2

Generating prefixes with an edge_ngram tokenizer

A custom analyzer can attach an edge_ngram tokenizer with minimum and maximum prefix lengths. For “bond,” a configuration using sizes 2 through 6 produces “bo,” “bon,” and “bond” (with longer tokens continuing up to the configured maximum). The _analyze API lets you inspect the generated terms before using the analyzer in an index. section 7.7.2

..
"tokenizer": {
  "my_edge_ngram_tokenizer":{
    "type":"edge_ngram",
     "min_gram":2,
     "max_gram":6,
     "token_chars":["letter","digit"]
   }
}

Inspect the tokenizer fragment that sets edge_ngram, min_gram, max_gram, and accepted token characters. section 7.7.2

For typeahead search, Elasticsearch can also provide the search_as_you_type field, which creates analyzed subfields automatically. A bool_prefix multi_match query searches the main field and its shingle-based subfields together. section 4.6.6

How Elasticsearch in Action, Second Edition covers it

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Related concepts

custom analyzerused by · A custom analyzer is a text-analysis configuration assembled from selected character filters, a tokenizer, and token filters.
n-gramkind of · An n-gram is a contiguous sequence of n consecutive items, commonly linguistic tokens or characters, drawn from a larger sequence.
indexingkind of · Indexing is the organization or use of positions, keys, or lookup structures to identify and retrieve selected data or elements.
tokenizerkind of · A tokenizer is a text-processing component or algorithm that segments text into discrete tokens and may map them to identifiers for computational processing.
autocompleteused by · Autocomplete is an interactive input feature that suggests or completes likely continuations of partially entered text, code, commands, or other values.

This explainer was generated by Manning's knowledge graph from the text of Elasticsearch in Action, Second Edition. The section links point to the parts of the book it draws on.