1.8 KiB
ArangoSearch Scorers
ArangoSearch accesses scorers directly by their internal names. The
name (in upper-case) of the scorer is the function name to be used in the
'SORT' section.
Function arguments, (excluding the first argument), are serialized as a
string representation of a JSON array and passed directly to the corresponding
scorer. The first argument to any scorer function is the reference to the
current document emitted by the FOR statement, i.e. it would be 'doc' for this
statement:
FOR doc IN someView
IResearch provides a 'bm25' scorer implementing the BM25 algorithm. This scorer optionally takes 'k' and 'b' positional parameters.
The user is able to run queries with the said scorer, e.g.
SORT BM25(doc, 1.2, 0.75)
The function arguments will then be serialized into a JSON representation:
[ 1.2, 0.75 ]
and passed to the scorer implementation.
Similarly an administrator may choose to deploy a custom DNA analyzer 'DnaRank'.
The user is then immediately able to run queries with the said scorer, e.g.
SORT DNARANK(doc, 123, 456, "abc", { "def": "ghi" })
The function arguments will then be serialized into a JSON representation:
[ 123, 456, "abc", { "def": "ghi" } ]
and passed to the scorer implementation.
Runtime-plugging functionality for scores is not available in ArangoDB at this point in time, so ArangoDB comes with a few default-initialized scores:
-
attribute-name: order results based on the value of attribute-name
-
BM25: order results based on the BM25 algorithm
-
TFIDF: order results based on the TFIDF algorithm