public interface SelectivityEstimator
Interface for any component that estimates the selectivity of a given expression.
Modifier and Type | Method and Description |
---|---|
double |
getConditionSelectivity(org.openrdf.query.algebra.ValueExpr condition,
org.openrdf.query.algebra.TupleExpr expr)
Estimates the reduction factor
f of applying condition
to expression expr . |
double |
getConditionSelectivity(org.openrdf.query.algebra.ValueExpr condition,
org.openrdf.query.algebra.TupleExpr expr,
org.openrdf.model.URI source)
Estimates the reduction factor
f of applying condition
to expression expr executed at source . |
double |
getJoinSelectivity(org.openrdf.query.algebra.Join expr)
Estimate the merge selectivity factor
f of a merge, such that
merge cardinality = cross product cardinality * f . |
double |
getJoinSelectivity(org.openrdf.query.algebra.Join expr,
org.openrdf.model.URI source)
Estimate the merge selectivity factor
f of a merge, such that
merge cardinality = cross product cardinality * f . |
double |
getVarSelectivity(String varName,
org.openrdf.query.algebra.TupleExpr expr,
org.openrdf.model.URI source)
Estimates the number of distinct values of a given variable.
|
double getJoinSelectivity(org.openrdf.query.algebra.Join expr, org.openrdf.model.URI source)
f
of a merge, such that
merge cardinality = cross product cardinality * f
.expr
- the merge expressionsource
- a referring data sourcedouble getJoinSelectivity(org.openrdf.query.algebra.Join expr)
f
of a merge, such that
merge cardinality = cross product cardinality * f
.expr
- the merge expressiondouble getVarSelectivity(String varName, org.openrdf.query.algebra.TupleExpr expr, org.openrdf.model.URI source)
varName
- the name of the variableexpr
- source
- a potential referring data sourcedouble getConditionSelectivity(org.openrdf.query.algebra.ValueExpr condition, org.openrdf.query.algebra.TupleExpr expr, org.openrdf.model.URI source)
f
of applying condition
to expression expr
executed at source
. That is, the cardinality
of the results is:
cardinality of executing expr
at source
* f
.condition
- expr
- source
- double getConditionSelectivity(org.openrdf.query.algebra.ValueExpr condition, org.openrdf.query.algebra.TupleExpr expr)
f
of applying condition
to expression expr
. That is, the cardinality of the results is
cardinality of results of expr
* f
.condition
- expr
- Copyright © 2015 SemaGrow - FP7. All rights reserved.