content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file 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, 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 org.apache.arrow.adapter.jdbc;
  
  import java.io.IOException;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import org.apache.arrow.memory.BufferAllocator;
  import org.apache.arrow.util.Preconditions;
  
  /**
   * Utility class to convert JDBC objects to columnar Arrow format objects.
   *
   * <p>This utility uses following data mapping to map JDBC/SQL datatype to Arrow data types.
   *
   * <p>CHAR --> ArrowType.Utf8 NCHAR --> ArrowType.Utf8 VARCHAR --> ArrowType.Utf8 NVARCHAR -->
   * ArrowType.Utf8 LONGVARCHAR --> ArrowType.Utf8 LONGNVARCHAR --> ArrowType.Utf8 NUMERIC -->
   * ArrowType.Decimal(precision, scale) DECIMAL --> ArrowType.Decimal(precision, scale) BIT -->
   * ArrowType.Bool TINYINT --> ArrowType.Int(8, signed) SMALLINT --> ArrowType.Int(16, signed)
   * INTEGER --> ArrowType.Int(32, signed) BIGINT --> ArrowType.Int(64, signed) REAL -->
   * ArrowType.FloatingPoint(FloatingPointPrecision.SINGLE) FLOAT -->
   * ArrowType.FloatingPoint(FloatingPointPrecision.SINGLE) DOUBLE -->
   * ArrowType.FloatingPoint(FloatingPointPrecision.DOUBLE) BINARY --> ArrowType.Binary VARBINARY -->
   * ArrowType.Binary LONGVARBINARY --> ArrowType.Binary DATE --> ArrowType.Date(DateUnit.MILLISECOND)
   * TIME --> ArrowType.Time(TimeUnit.MILLISECOND, 32) TIMESTAMP -->
   * ArrowType.Timestamp(TimeUnit.MILLISECOND, timezone=null) CLOB --> ArrowType.Utf8 BLOB -->
   * ArrowType.Binary
   *
   * @since 0.10.0
   */
  public class JdbcToArrow {
  
    /*----------------------------------------------------------------*
    |                                                                |
    |          Partial Convert API                        |
    |                                                                |
    *----------------------------------------------------------------*/
  
    /**
     * For the given JDBC {@link ResultSet}, fetch the data from Relational DB and convert it to Arrow
     * objects. Note here uses the default targetBatchSize = 1024.
     *
     * @param resultSet ResultSet to use to fetch the data from underlying database
     * @param allocator Memory allocator
     * @return Arrow Data Objects {@link ArrowVectorIterator}
     * @throws SQLException on error
     */
    public static ArrowVectorIterator sqlToArrowVectorIterator(
        ResultSet resultSet, BufferAllocator allocator) throws SQLException, IOException {
      Preconditions.checkNotNull(allocator, "Memory Allocator object cannot be null");
  
      JdbcToArrowConfig config = new JdbcToArrowConfig(allocator, JdbcToArrowUtils.getUtcCalendar());
      return sqlToArrowVectorIterator(resultSet, config);
    }
  
    /**
     * For the given JDBC {@link ResultSet}, fetch the data from Relational DB and convert it to Arrow
     * objects. Note if not specify {@link JdbcToArrowConfig#targetBatchSize}, will use default value
     * 1024.
     *
     * @param resultSet ResultSet to use to fetch the data from underlying database
     * @param config Configuration of the conversion from JDBC to Arrow.
     * @return Arrow Data Objects {@link ArrowVectorIterator}
     * @throws SQLException on error
     */
    public static ArrowVectorIterator sqlToArrowVectorIterator(
        ResultSet resultSet, JdbcToArrowConfig config) throws SQLException, IOException {
      Preconditions.checkNotNull(resultSet, "JDBC ResultSet object cannot be null");
      Preconditions.checkNotNull(config, "The configuration cannot be null");
      return ArrowVectorIterator.create(resultSet, config);
    }
  }
  