Fulltext functions

C8QL offers the following functions to filter data based on fulltext indexes.

FULLTEXT()

FULLTEXT(coll, attribute, query, limit) → docArray

Return all documents from collection coll, for which the attribute attribute matches the fulltext search phrase query, optionally capped to limit results.

Note

FULLTEXT() function requires the collection coll to have a fulltext index on attribute. If no fulltext index is available, this function will fail with an error at runtime. It doesn't fail when explaining the query however.

  • coll (collection): a collection
  • attribute (string): the attribute name of the attribute to search in
  • query (string): a fulltext search expression as described below
  • limit (number, optional): if set to a non-zero value, it will cap the result to at most this number of documents
  • returns docArray (array): an array of documents

FULLTEXT() is not meant to be used as an argument to FILTER, but rather to be used as the expression of a FOR statement:

FOR oneMail IN FULLTEXT(emails, "body", "banana,-apple")
    RETURN oneMail._id

query is a comma-separated list of sought words (or prefixes of sought words). To distinguish between prefix searches and complete-match searches, each word can optionally be prefixed with either the prefix: or complete: qualifier. Different qualifiers can be mixed in the same query. Not specifying a qualifier for a search word will implicitly execute a complete-match search for the given word:

  • FULLTEXT(emails, "body", "banana")
    Will look for the word banana in the attribute body of the collection collection.

  • FULLTEXT(emails, "body", "banana,orange")
    Will look for both words banana and orange in the mentioned attribute. Only those documents will be returned that contain both words.

  • FULLTEXT(emails, "body", "prefix:head")
    Will look for documents that contain any words starting with the prefix head.

  • FULLTEXT(emails, "body", "prefix:head,complete:aspirin")
    Will look for all documents that contain a word starting with the prefix head and that also contain the (complete) word aspirin. Note: specifying complete: is optional here.

  • FULLTEXT(emails, "body", "prefix:cent,prefix:subst")
    Will look for all documents that contain a word starting with the prefix cent and that also contain a word starting with the prefix subst.

If multiple search words (or prefixes) are given, then by default the results will be AND-combined, meaning only the logical intersection of all searches will be returned. It is also possible to combine partial results with a logical OR, and with a logical NOT:

  • FULLTEXT(emails, "body", "+this,+text,+document")
    Will return all documents that contain all the mentioned words. Note: specifying the + symbols is optional here.

  • FULLTEXT(emails, "body", "banana,|apple")
    Will return all documents that contain either (or both) words banana or apple.

  • FULLTEXT(emails, "body", "banana,-apple")
    Will return all documents that contain the word banana, but do not contain the word apple.

  • FULLTEXT(emails, "body", "banana,pear,-cranberry")
    Will return all documents that contain both the words banana and pear, but do not contain the word cranberry.

No precedence of logical operators will be honored in a fulltext query. The query will simply be evaluated from left to right.

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