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Fulltext indexes
Introduction to Fulltext Indexes
This is an introduction to ArangoDB’s fulltext indexes.
A fulltext index can be used to find words, or prefixes of words inside documents.
A fulltext index can be defined on one attribute only, and will include all words contained in documents that have a textual value in the index attribute. Since ArangoDB 2.6 the index will also include words from the index attribute if the index attribute is an array of strings, or an object with string value members.
For example, given a fulltext index on the translations attribute and the following
documents, then searching for лиса using the fulltext index would return only the
first document. Searching for the index for the exact string Fox would return the first
two documents, and searching for prefix:Fox would return all three documents:
{ translations: { en: "fox", de: "Fuchs", fr: "renard", ru: "лиса" } }
{ translations: "Fox is the English translation of the German word Fuchs" }
{ translations: [ "ArangoDB", "document", "database", "Foxx" ] }
If the index attribute is neither a string, an object or an array, its contents will not be indexed. When indexing the contents of an array attribute, an array member will only be included in the index if it is a string. When indexing the contents of an object attribute, an object member value will only be included in the index if it is a string. Other data types are ignored and not indexed.
Accessing Fulltext Indexes from the Shell
collection.ensureIndex({ type: "fulltext", fields: [ "field" ], minLength: minLength })
Creates a fulltext index on all documents on attribute field.
Fulltext indexes are implicitly sparse: all documents which do not have
the specified field attribute or that have a non-qualifying value in their
field attribute will be ignored for indexing.
Only a single attribute can be indexed. Specifying multiple attributes is
unsupported.
The minimum length of words that are indexed can be specified via the
minLength parameter. Words shorter than minLength characters will
not be indexed. minLength has a default value of 2, but this value might
be changed in future versions of ArangoDB. It is thus recommended to explicitly
specify this value.
In case that the index was successfully created, an object with the index
details is returned.
arangosh> db.example.ensureIndex({ type: "fulltext", fields: [ "text" ], minLength: 3 });
{
"id" : "example/1131890817",
"type" : "fulltext",
"fields" : [
"text"
],
"unique" : false,
"sparse" : true,
"minLength" : 3,
"isNewlyCreated" : true,
"code" : 201
}
arangosh> db.example.save({ text : "the quick brown", b : { c : 1 } });
{
"_id" : "example/1132415105",
"_rev" : "1132415105",
"_key" : "1132415105"
}
arangosh> db.example.save({ text : "quick brown fox", b : { c : 2 } });
{
"_id" : "example/1132611713",
"_rev" : "1132611713",
"_key" : "1132611713"
}
arangosh> db.example.save({ text : "brown fox jums", b : { c : 3 } });
{
"_id" : "example/1132808321",
"_rev" : "1132808321",
"_key" : "1132808321"
}
arangosh> db.example.save({ text : "fox jumps over", b : { c : 4 } });
{
"_id" : "example/1133004929",
"_rev" : "1133004929",
"_key" : "1133004929"
}
arangosh> db.example.save({ text : "jumps over the", b : { c : 5 } });
{
"_id" : "example/1133201537",
"_rev" : "1133201537",
"_key" : "1133201537"
}
arangosh> db.example.save({ text : "over the lazy", b : { c : 6 } });
{
"_id" : "example/1133398145",
"_rev" : "1133398145",
"_key" : "1133398145"
}
arangosh> db.example.save({ text : "the lazy dog", b : { c : 7 } });
{
"_id" : "example/1133594753",
"_rev" : "1133594753",
"_key" : "1133594753"
}
arangosh> db._query("FOR document IN FULLTEXT(example, 'text', 'the') RETURN document");
[
{
"b" : {
"c" : 1
},
"text" : "the quick brown",
"_id" : "example/1132415105",
"_rev" : "1132415105",
"_key" : "1132415105"
},
{
"b" : {
"c" : 5
},
"text" : "jumps over the",
"_id" : "example/1133201537",
"_rev" : "1133201537",
"_key" : "1133201537"
},
{
"b" : {
"c" : 6
},
"text" : "over the lazy",
"_id" : "example/1133398145",
"_rev" : "1133398145",
"_key" : "1133398145"
},
{
"b" : {
"c" : 7
},
"text" : "the lazy dog",
"_id" : "example/1133594753",
"_rev" : "1133594753",
"_key" : "1133594753"
}
]
[object ArangoQueryCursor, count: 4, hasMore: false]
arangosh> db.example.ensureIndex({ type: "fulltext", fields: [ "text" ], minLength: 3 });
arangosh> db.example.save({ text : "the quick brown", b : { c : 1 } });
arangosh> db.example.save({ text : "quick brown fox", b : { c : 2 } });
arangosh> db.example.save({ text : "brown fox jums", b : { c : 3 } });
arangosh> db.example.save({ text : "fox jumps over", b : { c : 4 } });
arangosh> db.example.save({ text : "jumps over the", b : { c : 5 } });
arangosh> db.example.save({ text : "over the lazy", b : { c : 6 } });
arangosh> db.example.save({ text : "the lazy dog", b : { c : 7 } });
arangosh> db._query("FOR document IN FULLTEXT(example, 'text', 'the') RETURN document");
collection.lookupFulltextIndex(attribute, minLength)
Checks whether a fulltext index on the given attribute attribute exists.