sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/meta/BeamSqlTable.java

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 * distributed with this work for additional information
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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
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package org.apache.beam.sdk.extensions.sql.meta;

import java.util.List;
import org.apache.beam.sdk.extensions.sql.impl.BeamTableStatistics;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.schemas.Schema;
import org.apache.beam.sdk.values.PBegin;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.POutput;
import org.apache.beam.sdk.values.Row;
import org.apache.beam.vendor.calcite.v1_20_0.org.apache.calcite.rex.RexNode;

/** This interface defines a Beam Sql Table. */
public interface BeamSqlTable {
  /** create a {@code PCollection<Row>} from source. */
  PCollection<Row> buildIOReader(PBegin begin);

  /** create a {@code PCollection<Row>} from source with predicate and/or project pushed-down. */
  PCollection<Row> buildIOReader(PBegin begin, BeamSqlTableFilter filters, List<String> fieldNames);

  /** create a {@code IO.write()} instance to write to target. */
  POutput buildIOWriter(PCollection<Row> input);

  /** Generate an IO implementation of {@code BeamSqlTableFilter} for predicate push-down. */
  BeamSqlTableFilter constructFilter(List<RexNode> filter);

  /** Whether project push-down is supported by the IO API. */
  boolean supportsProjects();

  /** Whether this table is bounded (known to be finite) or unbounded (may or may not be finite). */
  PCollection.IsBounded isBounded();

  /** Get the schema info of the table. */
  Schema getSchema();

  /**
   * Estimates the number of rows or the rate for unbounded Tables. If it is not possible to
   * estimate the row count or rate it will return BeamTableStatistics.BOUNDED_UNKNOWN.
   */
  BeamTableStatistics getTableStatistics(PipelineOptions options);
}