Define Atlas Search Indexes¶

Name of the analyzer to use with this autocomplete mapping. You can use any Atlas Search analyzer except the lucene.kuromoji language analyzer and the following custom analyzer tokenizers and token filters:

• nGram Tokenizer
• edgeGram Tokenizer
• daitchMokotoffSoundex Token Filter
• nGram Token Filter
• edgeGram Token Filter
• shingle Token Filter

The tokenization strategy to use when indexing the field for autocompletion. Value can be one of the following:

• edgeGram - to create indexable tokens, referred to as grams, from variable-length character sequences starting at the left side of the words as delimited by the analyzer used with this autocomplete mapping.

• rightEdgeGram - to create indexable tokens, referred to as grams, from variable-length character sequences starting at the right side of the words as delimited by the analyzer used with this autocomplete mapping.

  Note

  You can specify rightEdgeGram only in the JSON Editor. You can't select the rightEdgeGram tokenization strategy in the Visual Editor.

• nGram - to create indexable tokens, referred to as grams, by sliding a variable-length character window over a word. Atlas Search creates more tokens for nGram than edgeGram or rightEdgeGram. Therefore, nGram takes more space and time to index the field. nGram is better suited for querying languages with long, compound words or languages that don't use spaces.

For example, consider the following sentence:

The quick brown fox jumps over the lazy dog.

When tokenized with minGrams value of 2 and maxGrams value of 5, Atlas Search indexes the following sequence of characters based on the tokenization value you choose:

edgeGram

Th
The
The{SPACE}
The q
qu
qui
quic
quick
...

rightEdgeGram

og
dog
{SPACE}dog
y dog
zy
azy
lazy
{SPACE}lazy
he
the
{SPACE}the
r the
er
ver
over
{SPACE}over
...

nGram

Th
The
The{SPACE}
The q
he
he{SPACE}
he q
he qu
e{SPACE}
e q
e qu
e qui
{SPACE}q
{SPACE}qu
{SPACE}qui
{SPACE}quic
qu
qui
quic
quick
...

The setting to indicate whether diacritics should be included or removed from the indexed text. Value can be one of the following:

• true - to ignore diacritic marks in the index and query text. Returns results with and without diacritic marks. For example, a search for cafè returns results with the characters cafè and cafe.
• false - to include diacritic marks in the index and query text. Returns only results that match the strings with or without diacritics in the query. For example, a search for cafè returns results only with the characters cafè. A search for cafe returns results only with the characters cafe.

If set to true, Atlas Search indexes all fields in the collection except:

• Fields of certain data types. To learn more, see BSON Data Types.
• Any fields that you explicitly exclude using the fields parameter.

If omitted or set to false, you must specify individual fields to index.

Specifies whether or not to index shapes. By default, Atlas Search:

• Indexes points, even when nested.
• Does not index shape geometries such as lines and polygons.

Value can be:

• true to index shapes and points
• false to index only points

The data type of the field to index. Values are:

• int64 - for indexing large integers without loss of precision and for rounding double values to integers. You can't use this type to index large double values.
• double - for indexing large double values without rounding.

To learn more, see example below.

Specifies the amount of information to store for the indexed field. Value can be one of the following:

• docs - Only indexes documents. The frequency and position of the indexed term are ignored. Only a single occurence of the term is reflected in the score.
• freqs - Only indexes documents and term frequency. The position of the indexed term is ignored.
• positions - Indexes documents, term frequency, and term positions.
• offsets - (Default) Indexes documents, term frequency, term positions, and term offsets. This option is required for Highlighting.

Specifies whether to include or omit the field length in the result when scoring. The length of the field is determined by the number of tokens produced by the analyzer for the field. Value can be one of the following:

• include - to include the field length when scoring.
• omit - to omit the field length when scoring.

If value is include, Atlas Search uses the length of the field to determine the higher score when scoring. For example, if two documents match an Atlas Search query, the document with the shorter field length scores higher than the document with the longer field length.

If value is omit, Atlas Search ignores the field length when scoring.