A named expression that can be evaluated at search time and used for ranking or thresholding
in a search query.
Version: (assembly version)
public class NamedRankExpression : Object
The NamedRankExpression type exposes the following members
Gets and sets the property RankExpression.
The expression to evaluate for ranking or thresholding while processing a search request.
- Integer, floating point, hex and octal literals
- Shortcut evaluation
of logical operators such that an expression
a || b evaluates to the
a is true, without evaluating
- Arithmetic operators:
+ - * / %
- Boolean operators (including the ternary operator)
- Bitwise operators
- Comparison operators
- Common mathematic functions:
abs ceil erf exp floor lgamma ln log2 log10 max min sqrt pow
acosh acos asinh asin atanh atan cosh cos sinh sin tanh tan
- Random generation of a number between 0 and 1:
time in epoch:
min max functions that
operate on a variable argument list
Intermediate results are calculated as double precision floating point values. The
final return value of a
RankExpression is automatically converted from
floating point to a 32-bit unsigned integer by rounding to the nearest integer, with
a natural floor of 0 and a ceiling of max(uint32_t), 4294967295. Mathematical errors
such as dividing by 0 will fail during evaluation and return a value of 0.
The source data for a
RankExpression can be the name of an
of type uint, another
RankExpression or the reserved name text_relevance.
The text_relevance source is defined to return an integer from 0 to 1000 (inclusive)
to indicate how relevant a document is to the search request, taking into account
repetition of search terms in the document and proximity of search terms to each other
in each matching
IndexField in the document.
For more information about using rank expressions to customize ranking, see the Amazon
CloudSearch Developer Guide.
Gets and sets the property RankName.
The name of a rank expression. Rank expression names must begin with a letter and
can contain the following characters: a-z (lowercase), 0-9, and _ (underscore). Uppercase
letters and hyphens are not allowed. The names "body", "docid", and "text_relevance"
are reserved and cannot be specified as field or rank expression names.
Supported in: 4.5, 4.0, 3.5