A Static Rank Framework for Lucene / Solr

A Static Rank Framework for Lucene/SolrMike [email protected]

Static Rank for Solr/Lucene

• Dynamic Rank

• Why Static Rank

• Combining Scores

• Static Rank Components

Multiple Fields / Multiple Types

PubDate

IsNews

MediaType

TextBody

Continuous (Date, Int, Float, …)


PubDate

IsNews

MediaType

TextBody


Boolean (True, False)


PubDate

IsNews

MediaType

TextBody



Enum (Book, CD, DVD, Cassette)


PubDate

IsNews

MediaType

TextBody



Enum (Book, CD, DVD, Cassette)

Text (Natural Language)

Dynamic Rank

PubDate

IsNews

MediaType

TextBody

TF * IDF

Query

Dynamic Score

Dynamic Rank

• Query Dependent = F(Q,D)PubDate

IsNews

MediaType

TextBody

TF * IDF

Query

Dynamic Score

Dynamic Rank

• Query Dependent = F(Q,D)• Huge dynamic range (0.001-1502.3)

PubDate

IsNews

MediaType

TextBody

TF * IDF

Query

Dynamic Score

Dynamic Rank

• Query Dependent = F(Q,D)• Huge dynamic range (0.001-1502.3)• Not comparable across queries

PubDate

IsNews

MediaType

TextBody

TF * IDF

Query

Dynamic Score

Dynamic Rank

• Query Dependent = F(Q,D)• Huge dynamic range (0.001-1502.3)• Not comparable across queries• Not easily normalized

PubDate

IsNews

MediaType

TextBody

TF * IDF

Query

Dynamic Score

Why Static Rank?

PubDate

IsNews

MediaType

TextBody

Query

Static Rank System Static Score

Why Static Rank?

PubDate

IsNews

MediaType

TextBody

Query


All (dynamic) things equal, I want– Newer over older

Why Static Rank?

PubDate

IsNews

MediaType

TextBody

Query


All (dynamic) things equal, I want– Newer over older– CD over cassette

Why Static Rank?

PubDate

IsNews

MediaType

TextBody

Query


All (dynamic) things equal, I want– Newer over older– CD over cassette– Arbitrary feature A over arbitrary

feature B

Static Rank

PubDate

IsNews

MediaType

TextBody

Query

Static Rank System

• Query Independent = F(D)– i.e. static across queries

Static Score

Static Rank

PubDate

IsNews

MediaType

TextBody

Query

Static Rank System

• Query Independent = F(D)– i.e. static across queries

• More easily bounded

Static Score

Combined Rank

PubDate

IsNews

MediaType

TextBody

TF * IDF

Query

Static Rank System

Cust

om Q

uery

Com

bine

d Sc

ore

Framework - Requirements

Cust

om Q

uery

Com

bine

d Sc

ore

• Intuitive, hand-tunable, debuggable


Cust

om Q

uery

Com

bine

d Sc

ore

• Intuitive, hand-tunable, debuggable• Query-time only, no re-indexing


Cust

om Q

uery

Com

bine

d Sc

ore

• Intuitive, hand-tunable, debuggable• Query-time only, no re-indexing• Minimal parameters


Cust

om Q

uery

Com

bine

d Sc

ore

• Intuitive, hand-tunable, debuggable• Query-time only, no re-indexing• Minimal parameters• Static Rank should boost / demote– But not too much!– Docs should stay in their own dynamic

rank “neighborhood”.

Combining Scores - Approaches

Cust

om Q

uery

Com

bine

d Sc

ore

• Addition?– Dynamic(0.0001) + Static(0.3) = 0.3001– Dynamic(1542.1) + Static(0.3) = 1542.4– Difficult to get right across queries


Cust

om Q

uery

Com

bine

d Sc

ore

• Multiplication?– Dynamic(50.0) * Static(0.3) = 15.0– Dynamic(10.0) * Static(2.0) = 20.0– Could work, but awkward


Line

ar Q

uery

Com

bine

d Sc

ore

1. Bound StaticScore: -1.0 to 1.02. CScore = DScore*(100+S%*SScore)– At most, staticRank will boost/demote

dynamicScore by S%– CScore = 0.014 * (100+30*0.5)– CScore = 145.3 * (100+30*-0.5)

LinearQuery

Static Rank

PubDate

IsNews

MediaType

TextBody

Query


Static Rank

PubDate

IsNews

MediaType

TextBody

Query


• Extend solr.ValueSource/Parser

Static Rank

PubDate

IsNews

MediaType

TextBody

Query


• Extend solr.ValueSource/Parser • Uses field cache for inputs

Static Rank

PubDate

IsNews

MediaType

TextBody

Query


• Extend solr.ValueSource/Parser • Uses field cache for inputs• Extremely fast

Static Rank

PubDate

IsNews

MediaType

Static Rank

PubDate

IsNews

MediaType

AgoValueSource

years ago

Static Rank

PubDate

IsNews

MediaType

MuxValueSource

0

T

F

AgoValueSource

years ago

years ago

MuxValueSource Config

Static Rank

PubDate

IsNews

MediaType

0

T

F

EnumValueSource

MuxValueSourceAgoValueSource

years ago

years ago

EnumValueSource Config

• Maps Fixed-Vocabulary to YEARS AGO• A hierarchy and 3 values: MIN,0,MAX• All things equal (dynamically), DVD = +3.3 years

Static Rank

PubDate

IsNews

MediaType

0

T

F

SumValueSource

EnumValueSource


years ago

years ago

years ago

years ago ?

-1

1

Mapping YearsAgo to -1.0 – 1.0• Step Function: if > 10 years-ago = -1, else = +1• 1 parameter• Too abrupt


• Linear• No parameters (fixed)• Too gradual over 2000+ years


• Linear• No parameters (fixed)• Too gradual over 2000+ years

• Sigmoid• 2 parameters• Smooth over entire range• Easy to calculate

Sigmoid

Slope

Sigmoid

Slope x-intercept (year)

1.0

-1.0

Years-ago

x0 = 1.5 years ago

Static Rank

PubDate

IsNews

MediaType

0

T

F

SumValueSource

EnumValueSource


SigmoidValueSource

-1

1

years ago

years ago

years ago

SigmoidValueSource Config

Static Rank Config

Conclusion

• solr.ValueSource/Parser - fast and flexible

Conclusion


• CScore = DScore * (100 + S% * SScore)• -1.0 < SScore < 1.0

Conclusion


• CScore = DScore * (100 + S% * SScore)• -1.0 < SScore < 1.0

• “Time” as a common currency for static features

Documents

A Static Rank Framework for Lucene / Solr