io.delta.standalone.DeltaScan Maven / Gradle / Ivy
/*
* Copyright (2020-present) The Delta Lake Project Authors.
*
* 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 io.delta.standalone;
import java.util.Optional;
import io.delta.standalone.actions.AddFile;
import io.delta.standalone.data.CloseableIterator;
import io.delta.standalone.expressions.Expression;
/**
* Provides access to an iterator over the files in this snapshot.
*
* Typically created with a read predicate {@link Expression} to let users filter files. Please note
* filtering is only supported on partition columns and users should use
* {@link DeltaScan#getResidualPredicate()} to check for any unapplied portion of the input
* predicate.
*/
public interface DeltaScan {
/**
* Creates a {@link CloseableIterator} over files belonging to this snapshot.
*
* There is no iteration ordering guarantee among files.
*
* Files returned are guaranteed to satisfy the predicate, if any, returned by
* {@link #getPushedPredicate()}.
*
* @return a {@link CloseableIterator} over the files in this snapshot that satisfy
* {@link #getPushedPredicate()}
*/
CloseableIterator getFiles();
/**
* @return the input predicate passed in by the user
*/
Optional getInputPredicate();
/**
* @return portion of the input predicate that can be evaluated by Delta Standalone using only
* metadata (filters on partition columns). Files returned by {@link #getFiles()} are
* guaranteed to satisfy the pushed predicate, and the caller doesn’t need to apply them
* again on the returned files.
*/
Optional getPushedPredicate();
/**
* @return portion of the input predicate that may not be fully applied. Files returned by
* {@link #getFiles()} are not guaranteed to satisfy the residual predicate, and the
* caller should still apply them on the returned files.
*/
Optional getResidualPredicate();
}