/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.spi;
/**
* A ColumnIdentity keeps all the information needed to determine if a column
* has changed for a certain table.
* <p>
* The ColumnIdentity is saved as serialized bytes.
* <p>
* ColumnIdentity can be used to ensure that the columns used in view
* definition have not changed since the view was created.
*/
public interface ColumnIdentity
{
/**
* Serialize the column identity in a manner which is backwards compatible across releases.
*/
byte[] serialize();
/**
* Compare the identity of columns, even for deserialized instances from different releases.
*/
boolean equals(Object o);
/**
* Must be implemented to properly compare the equality of ColumnIdentity.
*/
int hashCode();
}