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JDBC Driver for Google Cloud Spanner

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package nl.topicus.jdbc.resultset;

import java.sql.ResultSet;
import java.sql.SQLException;
import nl.topicus.jdbc.shaded.com.google.cloud.spanner.BatchReadOnlyTransaction;
import nl.topicus.jdbc.shaded.com.google.cloud.spanner.Partition;
import nl.topicus.jdbc.statement.CloudSpannerStatement;

/**
 * A specialized version of a {@link ResultSet} that contains the results of one partition of a
 * partitioned query
 * 
 * @author loite
 *
 */
public class CloudSpannerPartitionResultSet extends CloudSpannerResultSet {
  private final Partition partition;

  private final BatchReadOnlyTransaction transaction;

  private boolean executed = false;

  public CloudSpannerPartitionResultSet(CloudSpannerStatement statement,
      BatchReadOnlyTransaction transaction, Partition partition, String sql) {
    super(statement, sql);
    this.transaction = transaction;
    this.partition = partition;
  }

  @Override
  public boolean next() throws SQLException {
    ensureOpenAndExecuted();
    return super.next();
  }

  @Override
  public CloudSpannerResultSetMetaData getMetaData() throws SQLException {
    ensureOpenAndExecuted();
    return super.getMetaData();
  }

  @Override
  public int findColumn(String columnLabel) throws SQLException {
    ensureOpenAndExecuted();
    return super.findColumn(columnLabel);
  }

  private void ensureOpenAndExecuted() throws SQLException {
    ensureOpen();
    if (!executed) {
      setResultSet(transaction.execute(partition));
      executed = true;
    }
  }

}