api/src/main/java/org/apache/iceberg/TableScan.java

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 * to you 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,
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package org.apache.iceberg;

import java.util.Collection;
import org.apache.iceberg.expressions.Expression;
import org.apache.iceberg.io.CloseableIterable;
import org.apache.iceberg.relocated.com.google.common.collect.Lists;

/**
 * API for configuring a table scan.
 * <p>
 * TableScan objects are immutable and can be shared between threads. Refinement methods, like
 * {@link #select(Collection)} and {@link #filter(Expression)}, create new TableScan instances.
 */
public interface TableScan {
  /**
   * Returns the {@link Table} from which this scan loads data.
   *
   * @return this scan's table
   */
  Table table();

  /**
   * Create a new {@link TableScan} from this scan's configuration that will use the given snapshot
   * by ID.
   *
   * @param snapshotId a snapshot ID
   * @return a new scan based on this with the given snapshot ID
   * @throws IllegalArgumentException if the snapshot cannot be found
   */
  TableScan useSnapshot(long snapshotId);

  /**
   * Create a new {@link TableScan} from this scan's configuration that will use the most recent
   * snapshot as of the given time in milliseconds.
   *
   * @param timestampMillis a timestamp in milliseconds.
   * @return a new scan based on this with the current snapshot at the given time
   * @throws IllegalArgumentException if the snapshot cannot be found
   */
  TableScan asOfTime(long timestampMillis);

  /**
   * Create a new {@link TableScan} from this scan's configuration that will override the {@link Table}'s behavior based
   * on the incoming pair. Unknown properties will be ignored.
   *
   * @param property name of the table property to be overridden
   * @param value value to override with
   * @return a new scan based on this with overridden behavior
   */
  TableScan option(String property, String value);

  /**
   * Create a new {@link TableScan} from this with the schema as its projection.
   *
   * @param schema a projection schema
   * @return a new scan based on this with the given projection
   */
  TableScan project(Schema schema);

  /**
   * Create a new {@link TableScan} from this that, if data columns where selected
   * via {@link #select(java.util.Collection)}, controls whether the match to the schema will be done
   * with case sensitivity.
   *
   * @return a new scan based on this with case sensitivity as stated
   */
  TableScan caseSensitive(boolean caseSensitive);

  /**
   * Create a new {@link TableScan} from this that loads the column stats with each data file.
   * <p>
   * Column stats include: value count, null value count, lower bounds, and upper bounds.
   *
   * @return a new scan based on this that loads column stats.
   */
  TableScan includeColumnStats();

  /**
   * Create a new {@link TableScan} from this that will read the given data columns. This produces
   * an expected schema that includes all fields that are either selected or used by this scan's
   * filter expression.
   *
   * @param columns column names from the table's schema
   * @return a new scan based on this with the given projection columns
   */
  default TableScan select(String... columns) {
    return select(Lists.newArrayList(columns));
  }

  /**
   * Create a new {@link TableScan} from this that will read the given data columns. This produces
   * an expected schema that includes all fields that are either selected or used by this scan's
   * filter expression.
   *
   * @param columns column names from the table's schema
   * @return a new scan based on this with the given projection columns
   */
  TableScan select(Collection<String> columns);

  /**
   * Create a new {@link TableScan} from the results of this filtered by the {@link Expression}.
   *
   * @param expr a filter expression
   * @return a new scan based on this with results filtered by the expression
   */
  TableScan filter(Expression expr);

  /**
   * Returns this scan's filter {@link Expression}.
   *
   * @return this scan's filter expression
   */
  Expression filter();

  /**
   * Create a new {@link TableScan} from this that applies data filtering to files but not to rows in those files.
   *
   * @return a new scan based on this that does not filter rows in files.
   */
  TableScan ignoreResiduals();

  /**
   * Create a new {@link TableScan} to read appended data from {@code fromSnapshotId} exclusive to {@code toSnapshotId}
   * inclusive.
   *
   * @param fromSnapshotId the last snapshot id read by the user, exclusive
   * @param toSnapshotId read append data up to this snapshot id
   * @return a table scan which can read append data from {@code fromSnapshotId}
   * exclusive and up to {@code toSnapshotId} inclusive
   */
  TableScan appendsBetween(long fromSnapshotId, long toSnapshotId);

  /**
   * Create a new {@link TableScan} to read appended data from {@code fromSnapshotId} exclusive to the current snapshot
   * inclusive.
   *
   * @param fromSnapshotId - the last snapshot id read by the user, exclusive
   * @return a table scan which can read append data from {@code fromSnapshotId}
   * exclusive and up to current snapshot inclusive
   */
  TableScan appendsAfter(long fromSnapshotId);

  /**
   * Plan the {@link FileScanTask files} that will be read by this scan.
   * <p>
   * Each file has a residual expression that should be applied to filter the file's rows.
   * <p>
   * This simple plan returns file scans for each file from position 0 to the file's length. For
   * planning that will combine small files, split large files, and attempt to balance work, use
   * {@link #planTasks()} instead.
   *
   * @return an Iterable of file tasks that are required by this scan
   */
  CloseableIterable<FileScanTask> planFiles();

  /**
   * Plan the {@link CombinedScanTask tasks} for this scan.
   * <p>
   * Tasks created by this method may read partial input files, multiple input files, or both.
   *
   * @return an Iterable of tasks for this scan
   */
  CloseableIterable<CombinedScanTask> planTasks();

  /**
   * Returns this scan's projection {@link Schema}.
   * <p>
   * If the projection schema was set directly using {@link #project(Schema)}, returns that schema.
   * <p>
   * If the projection schema was set by calling {@link #select(Collection)}, returns a projection
   * schema that includes the selected data fields and any fields used in the filter expression.
   *
   * @return this scan's projection schema
   */
  Schema schema();

  /**
   * Returns the {@link Snapshot} that will be used by this scan.
   * <p>
   * If the snapshot was not configured using {@link #asOfTime(long)} or {@link #useSnapshot(long)}, the current table
   * snapshot will be used.
   *
   * @return the Snapshot this scan will use
   */
  Snapshot snapshot();

  /**
   * Returns whether this scan should apply column name case sensitiveness as per {@link #caseSensitive(boolean)}.
   * @return true if case sensitive, false otherwise.
   */
  boolean isCaseSensitive();

}