org.apache.accumulo.core.constraints
Interface Constraint

All Known Implementing Classes:

VisibilityConstraint

public interface Constraint

Accumulo uses Constraint objects to determine if mutations will be applied to a table. This interface expects implementers to return violation codes. The reason codes are returned instead of arbitrary strings it to encourage conciseness. Conciseness is needed because violations are aggregated. If a user sends a batch of 10,000 mutations to accumulo, only aggregated counts about which violations occurred are returned. If the Constraint implementer was allowed to return arbitrary violation strings like the following : Value "abc" is not a number Value "vbg" is not a number Then this would not aggregate very well, because the same violation is represented with two different strings.

Nested Class Summary

static interface

Constraint.Environment

Method Summary

List<Short>	check(Constraint.Environment env, Mutation mutation) Checks a mutation for constrain violations.
String	getViolationDescription(short violationCode) Implementers of this method should return a short one sentence description of what a given violation code means.

Method Detail

getViolationDescription

String getViolationDescription(short violationCode)

Implementers of this method should return a short one sentence description of what a given violation code means.

check

List<Short> check(Constraint.Environment env,
                  Mutation mutation)

Checks a mutation for constrain violations. If the mutation contains no violations, then the implementation should return null. Otherwise it should return a list of violation codes. Violation codes must be non negative. Negative violation codes are reserved for system use.