Create a Collection with Collation

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Procedure

Restrictions and Limitations

Collation allows you to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

Procedure

Click the Create Collection button.

From the Collections screen, click the Create Collection button.

Enter the collection name.

Click the Additional preferences dropdown.

Check the Use Custom Collaton option.

Select a value for locale.

You are required to select a locale from the MongoDB supported languages.

All other collation options parameters are optional. For descriptions of the fields, see Collation.

Click Create Collection to create the collection.

Restrictions and Limitations

The following restrictions apply when the parameter numericOrdering is set to true:

Only contiguous non-negative integer substrings of digits are considered in the comparisons. numericOrdering does not support:
- +
- -
- exponents
Only Unicode code points in the Number or Decimal Digit (Nd) category are treated as digits.
If the number length exceeds 254 characters, the excess characters are treated as a separate number.

Example

Consider a collection with the following string number and decimal values:

[
  { "n": "1" },
  { "n": "2" },
  { "n": "-2.1" },
  { "n": "2.0" },
  { "n": "2.20" },
  { "n": "10"},
  { "n": "20" },
  { "n": "20.1" },
  { "n": "-10" },
  { "n": "3" }
]

The following find query uses a collation document containing the numericOrdering parameter:

 db.c.find(
  { }, { _id: 0 }
 ).sort(
   { n: 1 }
  ).collation( {
   locale: 'en_US',
   numericOrdering: true
} )

For more information on querying documents in Compass, see Query Your Data.

The operations returns the following results:

[
   { "n": "-2.1" },
   { "n": "-10" },
   { "n": "1" },
   { "n": "2" },
   { "n": "2.0" }
   { "n": "2.20" },
   { "n": "3" },
   { "n": "10" },
   { "n": "20" },
   {"n": "20.1" }
]

numericOrdering: true sorts the string values in ascending order as if they were numeric values.
The two negative values -2.1 and -10 are not sorted in the expected sort order because they have unsupported - characters.

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Clustered Collections