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2. Use Operators & Collectors

span

On this page

  • Definition
  • Syntax
  • Term Operator
  • Syntax
  • Fields
  • Positional Operators
  • contains
  • first
  • near
  • or
  • subtract

Definition

Note

The span operator is deprecated. Instead, use the phrase operator.

span

The span operator finds text search matches within regions of a text field. You can use it to find strings which are near each other to specified degrees of precision. The span operator is more computationally intensive than other operators, because queries must keep track of positional information.

span is a term-level operator, which means that the query field is not analyzed. Term-level operators work well with the Keyword Analyzer because the query field is treated as a single term, with special characters included.

span queries aren't ranked by score.

Syntax

span has the following syntax:

{
   $search: {
     "index": <index name>, // optional, defaults to "default"
     "span": {
       "term" | <positional-operator>": {
         <operator-specification>
       }
     }
   }
}

Note

span search queries can't use the compound operator.

Term Operator

You can use the term operator to specify the terms to search. The term operator is required and when you use it with span positional operators, it must be the innermost child of the positional operators.

Syntax

The term operator has the following syntax:

"term": {
  "path": "<path-to-field>",
  "query": "<terms-to-search>"
}

Fields

The term operator takes the following fields:

Option
Type
Required?
Description

path

string

yes

Indexed field to search.

query

string

yes

Term or phrase to search.

Positional Operators

You can use the positional operators to specify the position of the terms that you want to search with the term operator. The positional operators are of type document. You must specify at least one positional operator in your span operator query. The positional operators can take other span positional operators, recursively.

Note

About the Examples

The examples on this page use the sample_mflix.movies collection. If you load the sample data and create a dynamic index named default on the movies collection , you can run the following $search sample queries against the collection. The sample queries use the $limit stage to limit the results to 5 documents and the $project stage to exclude all fields except the title field in the results.

span takes the following optional positional operators.

contains

The contains positional operator matches terms that are contained within other terms. You can use positional operators recursively or just the term operator within contains to specify the search terms.

Syntax

The contains positional operator has the following syntax:

{
  "$search": {
    "span": {
      "contains": {
        "spanToReturn": "inner"|"outer",
        "little": { <positional-or-term-operator-specification> },
        "big": { <positional-or-term-operator-specification> }
      }
    }
  }
}

Fields

The contains positional operator takes the following fields:

Fields
Type
Required?
Description

big

document

yes

One or more positional operators specified recursively or just the term operator. The following table shows the type of query that span executes for big based on the value of spanToReturn.

outer

span matches terms from big that contain at least one term from little.

inner

span matches terms from little that are within terms from big.

little

document

yes

One or more positional operators specified recursively or just the term operator. The following table shows the type of query that span executes for little based on the value of spanToReturn.

inner

span matches terms from little that are within terms from big.

outer

span matches terms from big that contain at least one term from little.

score

document

no

Score to apply to the results of this search.

spanToReturn

string

yes

Type of query to execute and matching results to return. Value can be one of the following:

  • inner - to execute a within query that matches terms from little that are inside of terms from big

  • outer - to execute a contains query that matches terms from big that contain at least one term from little

Example

The following example query uses span.contains to find documents in which the term train appears with the terms great and robbery, where great and robbery can be up to 5 positions apart in the title field.

1db.movies.aggregate([
2  {
3    "$search": {
4      "span": {
5        "contains": {
6          "spanToReturn": "outer",
7          "little": {
8            "term": {
9              "path": "title",
10              "query": "train"
11            }
12          },
13          "big": {
14            "near": {
15              "clauses": [
16                {
17                  "term": {
18                    "path": "title",
19                    "query": "great"
20                  }
21                },
22                {
23                  "term": {
24                    "path": "title",
25                    "query": "robbery"
26                  }
27                }
28              ],
29              "slop": 5
30            }
31          }
32        }
33      }
34    }
35  },
36  {
37    "$limit": 5
38  },
39  {
40    "$project": {
41      "_id": 0,
42      "title": 1
43    }
44  }
45])
[
  { title: 'The Great Train Robbery' },
  { title: 'The Great Train Robbery' },
  { title: "The Great St. Trinian's Train Robbery" }
]

Atlas Search returns documents that contain the term train (specified using little) inside the terms great and robbery (specified using big). If you set spanToReturn on line 6 to inner, Atlas Search returns the same documents because the term train (specified using little) appears within the terms great and robbery (specified using big).

first

The first positional operator identifies the position of the search term by using a specified number. You can specify the search terms using positional operators recursively, or just the term operator. span matches documents where the position of the search term is less than or equal to the specified number.

Syntax

The first positional operator has the following syntax:

{
  "$search": {
    "span": {
      "first": {
        "endPositionLte": <term-position>,
        "operator": { <span-positional-or-term-operator-specification> },
        "score": { <score-options> }
      }
    }
  }
}

Fields

The first positional operator takes the following fields:

Option
Type
Required?
Description

endPositionLte

int

no

Number that specifies the position of the search term. If you specify a search for multiple terms, the last term should be less than or equal to this value. If omitted, defaults to 3.

operator

document

yes

Document that contains the positional operators or term operator options.

score

document

no

Score to apply to the results of this search.

Example

The following example queries use span.first to find documents in which the specified string appears in the title field. The endPositionLte parameter has a value of 2, which means that the search term specified using the term operator must be the first or second word in the field.

1db.movies.aggregate([
2  {
3    "$search": {
4      "span": {
5        "first": {
6          "endPositionLte": 2,
7          "operator": {
8            "term": {
9              "path": "title",
10              "query": "dance"
11            }
12          }
13        }
14      }
15    }
16  },
17  {
18    "$limit": 5
19  },
20  {
21    "$project": {
22      "_id": 0,
23      "title": 1
24    }
25  }
26])
[
  { title: 'Dance Program' },
  { title: 'Slam Dance' },
  { title: 'Last Dance' },
  { title: 'War Dance' },
  { title: 'Delhi Dance' }
]

Atlas Search returns the documents that contain search word dance in the first or second position of the title field.

1db.movies.aggregate([
2  {
3    "$search": {
4      "span": {
5        "first": {
6          "endPositionLte": 2,
7          "operator": {
8            "or": {
9              "clauses": [
10                { "term": { "path": "title", "query": "man" } },
11                { "term": { "path": "title", "query": "woman" } }
12              ]
13            }
14          }
15        }
16      }
17    }
18  },
19  {
20    "$limit": 5
21  },
22  {
23    "$project": {
24      "_id": 0,
25      "title": 1
26    }
27  }
28])
[
  { title: "Everybody's Woman" },
  { title: 'Marked Woman' },
  { title: 'Wonder Man' },
  { title: 'Designing Woman' },
  { title: 'Watermelon Man' }
]

Atlas Search returns documents that contain the search word man or woman in the first or second position of the title field. Atlas Search does not return both search terms in the same title because the example includes the or operator clauses to specify the search terms.

near

The near positional operator matches two or more clauses that contain the search term near each other. You can specify the search terms using a list of positional operators recursively or just the term operator.

Syntax

The near positional operator has the following syntax:

{
  "$search": {
    "span": {
      "near": {
        "clauses": [
          { <span-positional-or-term-operator-specification> },
          ...
        ],
        "slop": <distance-number>,
        "inOrder": true|false
      }
    }
  }
}

Fields

The near positional operator takes the following fields:

Field
Type
Required?
Description

clauses

array of documents

yes

Span clauses that must be near one another. Clauses can't be empty. Each document contains span positional or just the term operator options.

inOrder

boolean

no

Flag that specifies whether the search for terms in the clauses must be in the order specified and must not be overlapping.

Value can be one of the following:

  • true - to search for terms in the clauses in the specified order specified, without overlapping

  • false - to search for terms in the clauses in any order

If omitted, defaults to false.

score

document

no

Score to apply to the results of this search.

slop

integer

no

Allowable distance between terms in the clauses. Lower values allow less positional distance between the terms and greater values allow more distance between the words to satisfy the query. The default is 0, which means that words in the different clauses must be adjacent to be considered a match.

Example

The following example query uses span.near to search for documents in which the strings prince and pauper are found near each other. The inOrder parameter is set to false, so the search terms can be in any order. The slop parameter is set to 4, so the search terms can be separated by up to only 4 words.

1db.movies.aggregate([
2  {
3    "$search" : {
4      "span": {
5        "near": {
6          "clauses": [
7            { "term": { "path": "title", "query": "prince" } },
8            { "term": { "path": "title", "query": "pauper" } }
9          ],
10          "slop": 4,
11          "inOrder": false
12        }
13      }
14    }
15  },
16  {
17    "$limit": 5
18  },
19  {
20    "$project": {
21      "_id": 0,
22      "title": 1
23    }
24  }
25])
[ { title: 'The Prince and the Pauper' } ]

Atlas Search returns a document that contain search words prince and pauper, separated by less than four words, in the title field.

or

The or positional operator matches any of two or more clauses. You can specify the search terms using a list of positional operators recursively or just the term operator.

Syntax

The or positional operator has the following syntax:

{
  "$search": {
    "span": {
      "or": {
        "clauses": [
          { <span-positional-or-term-operator-specification> },
          ...
        ],
        "score": { <scoring-options> }
      }
    }
  }
}

Fields

The or positional operator takes the following fields:

Option
Type
Required?
Description

clauses

array of documents

yes

Span clauses that specify the search terms. One of the clauses must match, and clauses can't be empty. Each document must contain span positional operators specified recursively or just the term operator options.

score

document

no

Score to apply to the results of this search.

Example

The following example query uses span.or clauses to specify two term operator queries that search for documents in which the title field has either city or country.

1db.movies.aggregate([
2  {
3    "$search" : {
4      "span": {
5        "or": {
6          "clauses": [
7            { "term": { "path": "title", "query": "city" } },
8            { "term": { "path": "title", "query": "country" } }
9          ],
10        }
11      }
12    }
13  },
14  {
15    "$limit": 5
16  },
17  {
18    "$project": {
19      "_id": 0,
20      "title": 1
21    }
22  }
23])
[
  { title: 'Country' },
  { title: 'City Lights' },
  { title: 'King & Country' },
  { title: 'Fat City' },
  { title: 'Atlantic City' }
]

Atlas Search returns the documents that contain the search words city or country in the title field, but not both in the same title.

subtract

The subtract positional operator removes matches that overlap with another match. You can specify the search terms using a list of positional operators recursively or just the term operator. The subtract clause can be used to exclude certain strings from your search results.

Syntax

The subtract positional operator has the following syntax:

{
  "$search": {
    "span": {
      "subtract": {
        "include": { <span-positional-or-term-operator-specification> },
        "exclude": { <span-positional-or-term-operator-specification> }
      }
    }
  }
}

Fields

The subtract positional operator takes the following fields:

Option
Type
Required?
Description

exclude

document

yes

Document that specifies the term or phrase matches to remove that overlap with the term or phrase matches specified in the include field. You can specify the term or phrase using any span positional operators and the term operator.

include

document

yes

Document that specifies the term matches to include using any positional operators or just the term operator.

score

document

no

Score to apply to the results of this search.

Example

The following example query uses span.subtract to search for documents in which the title field contains the words father and son, in any order, within 3 words of each other. It excludes any document in which the word like occurs between father and son.

1db.movies.aggregate([
2  {
3    "$search" : {
4      "span": {
5        "subtract": {
6          "include": {
7            "near": {
8              "clauses": [
9                { "term": { "path": "title", "query": "father" } },
10                { "term": { "path": "title", "query": "son" } }
11              ],
12              "inOrder": false,
13              "slop": 3
14            }
15          },
16          "exclude": { "term": { "path": "title", "query": "like" } }
17        }
18      }
19    }
20  },
21  {
22    "$limit": 5
23  },
24  {
25    "$project": {
26      "_id": 0,
27      "title": 1
28    }
29  }
30])
[
  { title: 'Father, Son & Holy Cow' },
  { title: 'My Father and My Son' },
  { title: 'Jimmy Rosenberg: The Father, the Son & the Talent' }
]

Atlas Search doesn't return the document with the title Like Father Like Son because although the title field includes the words father and son, it also has like between them, which is in the exclude criteria of the query.

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