DecayRanker

The DecayRanker class extends from the Function class and provides extra parameters.

public class DecayRanker extends CreateCollectionReq.Function

Constructor

This constructor initializes a new DecayRanker instance designed to create a decay ranker instance.

DecayRanker.builder()
    .name(String name)
    .description(String description)
    .functionType(FunctionType functionType)
    .inputFieldNames(List<String> inputFieldNames)
    .params(Map<String, String> params)
    .function(String function)
    .origin(Number origin)
    .scale(Number scale)
    .offset(Number offset)
    .decay(Number decay)
    .build();

BUILDER METHODS:

• name(String name)

  The name of the function. This identifier is used to reference the function within queries and collections.

• description(String description)

  A brief description of the function’s purpose. This can be useful for documentation or clarity in larger projects and defaults to an empty string.

• functionType(FunctionType functionType)

  The type of function for processing raw data. For DecayRanker, set this to FunctionType.RERANK.

• inputFieldNames(List<String> inputFieldNames)

  The name of the field containing the raw data that requires conversion to vector representation. For functions using FunctionType.RERANK, this parameter accepts only one field name.

• params(Map<String, String> params)

  A set of key-value pairs that configures the function properties.

• function(String function)

  The type of decay ranker to create. Possible values are: gauss, exp, and linear.

• origin(Number origin)

  The reference point from which decay score is calculated. Items at this value receive maximum relevance scores. For time-based decay, the time unit must match your collection data.

• scale(Number scale)

  The distance or time at which relevance drops to the decay value. Controls how quickly relevance declines. For time-based decay, the time unit must match your collection data. Larger values create a more gradual decline in relevance; smaller values create a steeper decline.

• offset(Number offset)

  A “no-decay zone” around the origin where items maintain full scores (decay score = 1.0).

  For time-based decay, the time unit must match your collection data.

  Items within this range of the origin maintain maximum relevance.

• decay(Number decay)

  A score value at the scale distance, controls curve steepness. Lower values create steeper decline curves; higher values create more gradual decline curves.

  Must be between 0 and 1.

RETURN TYPE:

DecayRanker

RETURNS:

A decay ranker instance.

Examples:

import io.milvus.v2.service.collection.request.CreateCollectionReq.Function;
import io.milvus.v2.service.vector.request.ranker.DecayRanker
import java.util.Collections;

// use the DecayRanker class
DecayRanker.builder()
    .function("gauss")
    .name("time decay")
    .inputFieldNames(Collections.singletonList("timestamp"))
    .origin(1000)
    .scale(10000)
    .offset(24)
    .decay(0.5)
    .build());
    
// Instead, you can use the Function class as well
CreateCollectionReq.Function rr = CreateCollectionReq.Function.builder()
    .functionType(FunctionType.RERANK)
    .name("time_decay")
    .description("time decay")
    .inputFieldNames(Collections.singletonList("timestamp"))
    .param("reranker", "decay")
    .param("function", "gauss")
    .param("origin", "1000")
    .param("scale", "10000")
    .param("offset", "24")
    .param("decay", "0.5")
    .build();